A solar storm was sent shooting towards the Earth by the Sun. Can the Internet shut down? Know how severe the online impact can be.
The Sun has hurled a solar storm into space and sent it careening on collision course towards the Earth. This poses multiple dangers here on the third rock from the Sun, especially to our digital world. How big an impact will it have on online infrastructure? Will our Internet be safe? Well, the Sun has an 11-year cycle during which it shoots out super-heated magnetised magma, referred to as ‘coronal mass ejections’ (CMEs) into space. The severity of the solar storm depends on which part of the cycle the Sun is in. Also, what is important is the location of the Earth in comparison to the trajectory of the solar flare. If an extremely severe solar storm is generated and the Earth is in its path, there will be a big impact on all communications devices including mobile phones, computers as well as electricity grids. However, if the Earth is not in the path of this severe solar storm, it escapes the destructive consequences.
Solar storm impact: If a really big solar storm was to hit the Earth, it would have an impact on our online activities – it could take down the Internet. How will solar storm affect online activities? Well, Science Focus explains the impact of a solar flare on Earth in an easy to understand manner, “If a CME on a similar scale was to strike the Earth today, it could damage the electronics in orbiting satellites, disrupting navigation and communications systems, as well as the GPS time synchronization that the internet relies on to function. It would also create a surge of electromagnetic radiation in the atmosphere, causing huge currents in our power grids which could burn out electrical transformers, leading to length(y) outages.” But remember, this is a worst-case scenario possibility.
For the past few years, the possibility of a new (and big!) planet hanging around in the outermost regions of the solar system has tantalized scientists and the public alike. But after years of searching, astronomers have found zero new planets in that realm.
We’ve only been studying the region of the solar system past the orbit of Neptune for a few decades now, and after a moment of introspection it’s easy to see why: astronomy out here is kind of challenging, because the objects we’re trying to hunt down are a) very, very small and b) very, very far away. That makes them hard to spot.
Besides Pluto, discovered by basically blind luck in 1930, our understanding of the outer solar system was completely absent until 1992, when astronomers found their first Kuiper Belt object, a frozen little remnant from the formation of the solar system, lazily circling the sun in near perfect darkness beyond Neptune.
Since then, we’ve found thousands more such objects, categorizing and subcategorizing them as we go (as astronomers are wont to do). For the rest of our story, we’ll be focusing on a class of characters known as extreme trans-neptunian objects, or eTNOs. If you’ve never heard that jargon term before, don’t be scared: it’s astronomese for “really, really far past the orbit of Neptune.”
In 2003, astronomers discovered perhaps the strangest eTNO yet, Sedna. Sedna is big, about half the size of Pluto, but sits in a truly ridiculous orbit. Over the course of 11,000 years (twice that of all of recorded human history), Sedna swings from 76 astronomical units (AU; one AU is the distance between the sun and Earth) to over 900 AU, then back again.
Sedna is weird.
The case for nine
The orbit of Sedna is so weird that it demands explanation. How can such a massive almost-planet reach such a huge, detached orbit without getting completely ejected from the solar system altogether?
Perhaps there’s something else out there, keeping Sedna on a leash.
More recently, a couple teams of astronomers began to notice some other funky eTNOs. Namely, a group of half a dozen objects with similar orbits — they had roughly the same amount of ellipticity, and those ellipses were clustered together.
Imagine picking up a random flower from a field and looking at the petals. You’d normally expect the petals to be distributed evenly around the flower, but if you saw them all clustered together you might think something suspicious was going on.
And the same goes for these strange eTNOs: there was no reason to expect these kinds of orbits by random chance. The best explanation, the astronomers claimed, was that a new planet, Planet Nine (until we come up with a better name), was shaping and shepherding them in their orbits.
But still eight remain
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It’s not a bad argument. The inability to explain the orbit of Uranus led to the detection of Neptune, so there is some historical antecedent to the strategy. And since then, more eTNOs have been found in the same strange, clustered orbits.Advertisement
But in the years since the claim of a ninth planet made headlines, astronomers haven’t snagged a picture of it. Which isn’t too worrisome, at least not yet: if Planet Nine exists, it is very small (relatively) and very far away, making it hard to spot.
And in that same time, other astronomers have weighed in, arguing that the special eTNOs aren’t so special after all. It could be that because of the way our surveys are designed and conducted, we’re simply more likely to spot eTNOs with these funky orbits, and not any of their friends with more normal orbits. In other words, these eTNOs aren’t shepherded by some mysterious entity in the outer solar system. There’s simply nothing to explain — they only look different because we haven’t finished looking yet.
What’s more, it’s hard to square the existence of a ninth planet with the formation of the solar system as we currently understand it. Astronomers can, of course, work to fold in a ninth planet (say, by arguing that it’s an ejected failed core of a planet or a captured rogue exoplanet), but the more complicated the scenario gets, the harder it is to swallow.
Without a smoking-gun picture of the planet, the astronomical community isn’t going to be fully swayed by the wayward motion of a handful of iceballs in the outer solar system. So for now the search for a new planet continues.
Extraterrestrial life refers to life forms that did not originate and are not indigenous to our planet. So this term covers all possible types of life outside the Earth: These can be viruses, but also plant-like life forms. Some go even further: they are looking for creatures that are very similar to humans in their complexity or even surpass them, popularly known as aliens. But if there is extraterrestrial life, why hasn’t anyone heard about it until now? Do so-called aliens even exist? The Fermi Paradox addresses this very question. What approaches there are to this you can find out here!
Why haven’t we found aliens yet?
A new paper on the Fermi paradox convincingly shows why we will probably never find aliens.
One summer night, when I was a child, my mother and I were scouring the night sky for stars, meteors, and planets.
Suddenly, an object with a light that pulsed steadily from bright to dim caught my eye. It didn’t have the usual red blinkers of an aircraft and was going far too slowly to be a shooting star.
Obviously, it was aliens.
My excitement was short-lived as my mother explained it was a satellite catching the sun as it tumbled along its orbit. I went to bed disappointed: The X-files was on TV twice a week back then, and I very much wanted to believe.
Today that hope is still alive and well, in Hollywood films, the public imagination, and even among scientists. Scientists first began searching for alien signals shortly after the advent of radio technology around the turn of the 20th century, and teams of astronomers across the globe have been taking part in the formal Search for Extraterrestrial Intelligence (SETI) since the 1980s.
Yet the universe continues to appear devoid of life.
Now, a team of researchers at the University of Oxford brings a new perspective to this conundrum. In early June, Anders Sandberg, Eric Drexler, and Toby Ord of the Future of Humanity Institute (FHI) released a paper that may solve the Fermi paradox — the discrepancy between our expected existence of alien signals and the universe’s apparent lack of them — once and for all.
Using fresh statistical methods, the paper re-asks the question “Are we alone?” and draws some groundbreaking conclusions: We Earthlings are not only likely to be the sole intelligence in the Milky Way, but there is about a 50 percent chance we are alone in the entire observable universe.
While the findings are helpful for thinking about the likelihood of aliens, they may be even more important for reframing our approach to the risk of extinction that life on Earth may face in the near future.
Where is everybody?
In 1950, while working at Los Alamos National Laboratory, physicist Enrico Fermi famously exclaimed to his colleagues over lunch: “Where is everybody?”
He had been pondering the surprising lack of evidence of other life outside of our planet. In a universe that had been around for some 14 billion years, and in that time developed more than a billion trillion stars, Fermi reasoned there simply must be other intelligent civilizations out there. So where are they?
We still don’t know, and the Fermi paradox has only strengthened with time. Since the 1950s, humans have walked on the moon, sent a probe beyond our solar system, and even sent an electric sports car into orbit around the sun for fun. If we can go from rudimentary wooden tools to these feats of engineering in under a million years, surely there would have been ample opportunity in our 13.8 billion-year-old universe for other civilizations to have progressed to a similar level — and far beyond — already?
And then, surely there would be some lingering radio signals or visual clues of their expansion reaching our telescopes.
How scientists try to tackle the Fermi paradox, and why this paper is different
Space is a large place, and the task of accurately estimating the likelihood of little green menisn’t exactly easy.
In 1961, astronomer Frank Drake proposed a formula that multiplied seven “parameters” together to estimate N, the number of detectable civilizations we should expect within our galaxy at a given moment in time:
The Drake equation was only intended as a rough tool to stimulate scientific discussion around the probability of extraterrestrial life. However, in the absence of any reasonable alternatives, it has remained astronomers’ only method of calculating the probability of extraterrestrial intelligence. This is problematic because while some parameters, such as R* — the rate of new star formation per year — are relatively well-known, others remain hugely uncertain.
Take L, the average lifespan of a detectable civilization. If we look at the average length of the past civilizations here on Earth, it wouldn’t be unreasonable to assume a low value. If the Romans, Incas, or Egyptians are anything to go by, it seems hard to make it past a few hundred years. On the flip-side, you could argue that once a civilization becomes technologically advanced enough to achieve interstellar travel, it could conceivably last many billions of years.
This enormous uncertainty leaves the Drake equation ultimately vulnerable to the optimism or pessimism of whoever wields it. And this is reflected in previous scientific papers whose results give values of N ranging anywhere from 10 to many billions.
As astronomer and SETI co-founder Jill Tarter eloquently put it in an interview with National Geographic in 2000: “The Drake Equation is a wonderful way to organize our ignorance.”
Sincere attempts to overcome this vulnerability have previously been made via selecting a handful of conservative, medium, and bullish best estimates for each parameter value and then taking an average across them.
In their new paper, titled “Dissolving the Fermi Paradox,” the FHI researchers dispute this method by demonstrating how this technique typically produces a value of N far higher than it should, creating the illusion of a paradox.
This is because simply selecting a few point estimates and plugging them into the Drake Equation misrepresents the state of our knowledge. As an example, imagine three scientists who have differing opinions on the value of L:
If you take a normal, linear average of all the possible integer values from one to 1000, you would implicitly factor scientist C’s opinion 90 times more than scientist A’s because their range of belief is 90 times larger. If you use a logarithmic scale to represent the above so that each scientist’s range corresponds to one order of magnitude, all three opinions will be represented more equally.
Therefore, the researchers represented the full range of possible values on a logarithmic scale and ran millions of simulations to obtain more statistically reliable estimates for N. They then applied a technique known as a Bayesian update to those results.That means mathematically incorporating the information that we have not discovered extraterrestrial intelligence yet (because the absence of evidence of aliens is evidence itself!).
This two-stage process produced striking results: Based upon the current state of astrobiological knowledge, there’s a 53 to 99.6 percent chance we are the only civilization in this galaxy and a 39 to 85 percent chance we are the only one in the observable universe.
This implies that life as we know it is incomprehensibly rare, and if other intelligences exist, they are probably far beyond the cosmological horizon and therefore forever invisible to us.
But life can’t be that rare, can it?
To be clear, the paper’s authors do not appear to be making any definitive claim about whether or not aliens exist; simply, our current knowledge across the seven parameters suggests a high likelihood of us being alone. As new information becomes available, they would update that likelihood accordingly.For example, if we discover a second instance of abiogenesis — the process of rudimentary life emerging from non-living matter — on a comet or another planet, then this would narrow the uncertainty on the fl parameter significantly.
Nonetheless, their results have certainly caused a stir, especially after SpaceX CEO Elon Musk tweeted them:
Many reacted to the paper’s findings by calling it anthropocentric and narrow-minded, arguing that any conclusion suggesting we Earthlings are somehow special is simply human arrogance.
This is somewhat understandable because the idea that intelligent life is extremely rare in the universe feels completely counterintuitive. We exist, along with other intelligent life like dolphins and octopi, so we assume what we see must be extrapolatable beyond Earth.
But this alone is not proof that intelligent civilizations are therefore ubiquitous.Whether the true likelihood is as high as one in two, or as inconceivable as one in a trillion trillion trillion, the mere ability to consciously ask ourselves that question depends on the fact that life has already successfully originated.
This phenomenon is known as an observer selection effect — a bias that can occur when thinking about the likelihood of an event because an observer has to be there to observe the event in the first place. As we only have one data point (us), we have no reliable way to predict the true likelihood of intelligent life. The only conclusion we can confidently draw is that it can exist.
So if we are alone, is this good or bad news?
Regardless of which side you take, the idea that we might be alone in the universe raises serious scientific and philosophical questions. Is our rareness something to celebrate or be disappointed by? What would it mean for humans to be the only conscious entities in the universe?
This last question matters hugely. Not only are we depleting our environmental resources at an unsustainable pace, but for the first time in the history of mankind, we’ve reached the technological stage where we hold the entire future of our species in our own hands.Within a few years we built enough nuclear weapons to exterminate every human on earth many times over and made these weapons available to our leaders on a hair-trigger. Each decade has brought us novel technologies with ever-increasing potential for both immense good and immense destruction.
As we rang in the new year, the Bulletin of Atomic Scientists moved the Doomsday Clock to the closest it has ever been to midnight. Meanwhile, estimates from various specialists in existential risksuggest somewhere between a 5 to 19 percent chance of complete human extinction by the end of this century — an unacceptably large probability considering the stakes.
Not only does this dark gamble affect the 7 billion of us alive today; if you factor in the moral weight of the billion billions of future people who would also never get to live out their existences, it becomes clear that we urgently need to get our collective act together.
As Carl Sagan famously said in his 1990 Pale Blue Dot speech: “In all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. The Earth is the only world known so far to harbor life. … the Earth is where we make our stand.”
He’s not wrong, especially in light of this paper’s findings. If humanity really is the only civilization that may ever exist in this universe, then we shoulder a responsibility on a truly astronomical scale.
The Juno spacecraft made its most recent flyby of the giant planet Jupiter on June 8, 2021. Shortly before its closest point to Jupiter – the 34th of the mission, or perijove 34 – Juno flew closer to Jupiter’s large moon Ganymede than any spacecraft has in more than two decades. On July 14, NASA released the beautiful video above. It lets you ride along with the Juno spacecraft on this most recent sweep past Ganymede and Jupiter. The video is gorgeous and evocative. Juno’s principal investigator Scott Bolton of the Southwest Research Institute in San Antonio said in a statement:
The animation shows just how beautiful deep space exploration can be. It’s a way for people to imagine exploring our solar system firsthand by seeing what it would be like to be orbiting Jupiter and flying past one of its icy moons.
The images to make this time-lapse animation came from JunoCam, the visible-light camera/telescope aboard the Juno spacecraft. NASA
The 3:30-minute-long animation begins with Juno approaching Ganymede. It passed within 645 miles (1,038 km) of Ganymede’s surface at a relative velocity of 41,600 mph (67,000 kph). The imagery shows several of the moon’s dark and light regions. Darker regions are believed to result from ice sublimating into the surrounding vacuum, leaving behind darkened residue. The imagery also shows the crater Tros, which is among the largest and brightest crater scars on Ganymede.
It takes just 14 hours, 50 minutes for Juno to travel the 735,000 miles (1.18 million km) between Ganymede and Jupiter. The viewer is transported to within just 2,100 miles (3,400 km) above Jupiter’s spectacular cloud tops. By that point, Jupiter’s powerful gravity has accelerated the spacecraft to almost 130,000 mph (210,000 kph) relative to the planet.
Among the Jovian atmospheric features that can be seen are the circumpolar cyclones at the north pole and five of the gas giant’s string of pearls. These are eight massive storms rotating counterclockwise in Jupiter’s southern hemisphere. They appear as white ovals.
Using information that Juno has learned from studying Jupiter’s atmosphere, the animation team simulated lightning one might see as we pass over Jupiter’s giant thunderstorms.
How they made the video
Citizen scientist Gerald Eichstädt used composite images of Ganymede and Jupiter to give us the camera’s point of view. For both Ganymede and Jupiter, NASA said:
JunoCam images were orthographically projected onto a digital sphere and used to create the flyby animation. Synthetic frames were added to provide views of approach and departure for both Ganymede and Jupiter.
Juno mission extended to 2025
NASA said that, as planned, Jupiter’s gravitational pull has now affected Juno’s orbit. The craft has been in a highly elliptical polar orbit of 53 days since 2016. In other words, it has been passing close to the giant planet only that often. Now Jupiter’s strong gravity has reduced Juno’s orbit to 43 days.
The Juno mission was originally scheduled to end in July 2021. But in January of this year, NASA extended the mission. Juno will now continue exploring Jupiter through September 2025, or until the spacecraft’s end of life. NASA said on January 13, 2021:
This expansion tasks Juno with becoming an explorer of the full Jovian system – Jupiter and its rings and moons – with multiple rendezvous planned for three of Jupiter’s most intriguing Galilean moons: Ganymede, Europa, and Io.
The next Juno flyby of Jupiter, the 35th of the mission, is scheduled for a few days from now, July 21, 2021.
Bottom line: A beautiful video showing the most recent flyby of the Juno spacecraft at Jupiter. In the course of this flyby, Juno came closer to Jupiter’s large moon Ganymede than any spacecraft has in two decades.
These New Technologies Could Make Interstellar Travel Real
Long considered science fiction, leaving the solar system and speeding amid the stars may soon be within reach
(Credit: Charles Carter/Keck Institute for Space Studies via NASA)
On October 31, 1936, six young tinkerers nicknamed the “Rocket Boys” nearly incinerated themselves in an effort to break free of Earth’s gravity. The group had huddled in a gully in the foothills of California’s San Gabriel Mountains to test a small alcohol-fueled jet engine. They wanted to prove that rocket engines could venture into space, at a time when such ideas were widely met with ridicule. That goal was disrupted when an oxygen line caught fire and thrashed around wildly, shooting flames.
The Rocket Boys’ audacity caught the attention of aerodynamicist Theodore von Karman, who already worked with two of them at Caltech. Not far from the location of their fiery mishap, he established a small test area where the Rocket Boys resumed their experiments. In 1943, the site became the Jet Propulsion Laboratory (JPL), and von Karman its first director. JPL has since grown into a sprawling NASA field center with thousands of employees, yet it has managed to retain its founding motivation: test the limits of exploration, convention be damned.
They’ve had many successes over the years. In the early 1970s, JPL engineers built Pioneer 10, the first spacecraft to reach escape velocity from the solar system. A few years later, they followed up with Voyagers 1 and 2, the fastest of the many objects aimed at interstellar space. From the beginning of the Space Age to the launch of the Voyager spacecrafts — a span of just two decades — rocket scientists more than doubled flight speeds. But in the decades since, only one more spacecraft has followed the Voyagers out of the solar system, and nothing has done so at such a high speed. Now JPL’s rocketeers are getting restless again, and quietly plotting the next great leap.
The consistent theme of the new efforts is that the solar system is not enough. It is time to venture beyond the known planets, on toward the stars. John Brophy, a flight engineer at JPL, is developing a novel engine that could accelerate space travel by another factor of 10. Leon Alkalai, a JPL mission architect, is plotting a distant journey that would begin with an improbable, Icarus-esque plunge toward the sun. And JPL research scientist Slava Turyshev has perhaps the wildest idea of all, a space telescope that could provide an intimate look at a far-off Earth-like planet — without actually going there.
These are all long shots (not entirely crazy, according to Brophy), but if even one succeeds, the implications will be huge. The Rocket Boys and their ilk helped launch humans as a space-faring species. The current generation at JPL could be the ones to take us interstellar.
NASA’s Dawn spacecraft used ion propulsion to explore Ceres. Future missions could take the tech even further. (Credit: NASA-JPL/Caltech)
For Brophy, inspiration came from Breakthrough Starshot, an extravagantly bold project announced in 2016 by the late Stephen Hawking and Russian billionaire Yuri Milner. The ultimate aim of the project is to build a mile-wide laser array that could blast a miniature spacecraft to 20 percent the speed of light, allowing it to reach the Alpha Centauri star system (our closest stellar neighbor) in just two decades.
Brophy was skeptical but intrigued. Ambitious aspirations are nothing new for him. “JPL encourages people to think outside the box, and my wacky ideas are getting wackier in time,” he says. Even by that standard, the Starshot concept struck him as a little too far from technological reality. But he did begin to wonder if he could take the same concept but scale it down so that it might actually be feasible within our lifetimes.
What especially captivated Brophy was the idea of using a Starshot-style laser beam to help deal with the “rocket equation,” which links the motion of a spacecraft to the amount of propellant it carries. The rocket equation confronts every would-be space explorer with its cruel logic. If you want to go faster, you need more fuel, but more fuel adds mass. More mass means you need even more fuel to haul around that extra weight. That fuel makes the whole thing heavier still, and so on. That’s why it took a 1.4 million-pound rocket to launch the 1,800-pound Voyager probes: The starting weight was almost entirely fuel.
Since his graduate student days in the late 1970s, Brophy has been developing a vastly more efficient type of rocketry known as ion propulsion. An ion engine uses electric power to shoot positively charged atoms (called ions) out of a thruster at high velocity. Each atom provides just a tiny kick, but collectively they can push the rocket to a much greater velocity than a conventional chemical rocket. Better yet, the power needed to run the ion engine can come from solar panels — no heavy onboard fuel tanks or generators required. By squeezing more speed out of less propellant, ion propulsion goes a long way toward taming the rocket equation.
But ion engines come with drawbacks of their own. The farther they get from the sun, the more limited they are by how much electricity their solar panels can generate. You can make the panels huge, but then you add a lot of weight, and the rocket equation slams you again. And ion engines have such gentle thrust that they can’t leave the ground on their own; it then takes them a long time in space to accelerate to their record-breaking speeds. Brophy knows these issues well: He helped design the ion engine aboard NASA’s Dawn spacecraft, which just completed an 11-year mission to asteroid Vesta and dwarf planet Ceres. Even with its formidable 65-foot span of solar cells, Dawn went from zero to 60 in an unhurried four days.
An orbiting laser system could power an ion propulsion vehicle through the solar system, and prove reusable. (Credit: Jay Smith/Discover)
Ion the Prize
While Brophy was pondering this impasse between efficient engines and insufficient solar power, the Breakthrough Starshot concept came out, and it got the gears turning in his head. He wondered: What if you replaced sunshine with a high-intensity laser beam pointed at your spacecraft? Powered by the more efficient laser, your ion engine could run much harder while still saving weight by not having to carry your power source on board.about:blankabout:blank
Two years after his epiphany, Brophy is giving me a tour of an SUV-size test chamber at JPL, where he puts a high-performance ion engine through its paces. His prototype uses lithium ions, which are much lighter than the xenon ions Dawn used, and therefore need less energy to attain higher velocities. It also runs at 6,000 volts compared with Dawn’s 1,000 volts. “The performance of this thing would be very startling if you had the laser to power it up,” he says.
There’s just one minor issue: That laser does not exist. Although he drastically downsized the Starshot concept, Brophy still envisions a 100-megawatt space-based laser system, generating 1,000 times more power than the International Space Station, aimed precisely at a fast-receding spacecraft. “We’re not sure how to do that,” he concedes. It would be by far the biggest off-world engineering project ever undertaken. Once built, though, the array could be used over and over, with different missions, as an all-purpose rocket booster.
As an example, Brophy describes a lithium-ion-powered spacecraft with 300-foot wings of photovoltaic panels powering a full-size version of the engine he is developing at JPL. The laser would bathe the panels in light a hundred times as bright as sunshine, keeping the ion engine running from here to Pluto, about 4 billion miles away. The spacecraft could then coast along on its considerable velocity, racking up another 4 billion miles every year or two.
At that pace, a spacecraft could rapidly explore the dim areas where comets come from, or set off for the as-yet-undiscovered Planet 9, or go … almost anywhere in the general vicinity of the solar system.
“It’s like we have this shiny new hammer, so I go around looking for new nails to pound in,” Brophy says dreamily. “We have a whole long list of missions that you could do if you could go fast.”
Only the Voyager probes have passed the heliopause, leaving the sun’s influence. New probes may one day study the interstellar medium lying beyond. (Credit: NASA-JPL/Caltech)about:blankabout:blank
Interstellar Medium Well
After Brophy’s genial giddiness, it is a shock to talk to Alkalai, in charge of formulating new missions at JPL’s Engineering and Science Directorate. Sitting in his large, glassy office, he seems every bit the no-nonsense administrator, but he, too, is a man with an exploratory vision.
Like Brophy, Alkalai thinks the Breakthrough Starshot people have the right vision, but not enough patience. “We’re nowhere near where we need to be technologically to design a mission to another star,” he says. “So we need to start by taking baby steps.”
Alkalai has a specific step in mind. Although we can’t yet visit another star, we can send a probe to sample the interstellar medium, the sparse gas and dust that flows between the stars.
“I’m very interested in understanding the material outside the solar system. Ultimately, we got created from that. Life originated from those primordial dust clouds,” Alkalai says. “We know that there’s organic materials in it, but what kind? What abundances? Are there water molecules in it? That would be huge to understand.”about:blankabout:blank
The interstellar medium remains poorly understood because we can’t get our hands on it: A constant blast of particles from the sun — the solar wind — pushes it far from Earth. But if we could reach beyond the sun’s influence, to a distance of 20 billion miles (about 200 times Earth’s distance from the sun), we could finally examine, for the first time, pristine samples of our home galaxy.
Alkalai wants answers, and he wants to see the results firsthand. He’s 60, so that sets an aggressive schedule — no time to wait for giant space lasers. Instead, he proposes a simpler, albeit still unproven, technology known as a solar thermal rocket. It would carry a large cache of cold liquid hydrogen, protected somehow from the heat of the sun, and execute a shocking dive to within about 1 million miles of the solar surface. At closest approach, the rocket would let the intense solar heat come pouring in, perhaps by jettisoning a shield. The sun’s energy would rapidly vaporize the hydrogen, sending it racing out of a rocket nozzle. The combined push from the escaping hydrogen, and the assist from the sun’s own gravity, would let the ship start its interstellar journey at speeds up to 60 miles per second, faster than any human object yet —and it only gets faster from there.
“It’s very challenging, but we’re modeling the physics now,” Alkalai says. He hopes to begin testing elements of a thermal-rocket system this year, and then develop his concept into a realistic mission that could launch in the next decade or so. It would reach the interstellar medium another decade after that. In addition to sampling our galactic environment, such a probe could examine how the sun interacts with the interstellar medium, study the structure of dust in the solar system and perhaps visit a distant dwarf planet along the way.
It would be a journey, Alkalai says, “like nothing we’ve done in the past.”
How a solar gravitational lens works. (Credits: Courtesy of Slava Turyshev; The Aerospace Corp.; Jim Deluca/Jimiticus via YouYube (2); Jay Smith)
Catch A Glimpse
Solar thermal rockets and laser-ion engines, impressive as they may be, are still absurdly inadequate for crossing the tremendous gulf between our solar system and exoplanets — planets orbiting other stars. In the spirit of the Rocket Boys, Turyshev is not letting absurdity stop him. He is developing a cunning workaround: a virtual mission to another star.
Turyshev tells me he wants to send a space telescope to a region known as the solar gravitational lens (SGL). The area begins a daunting 50 billion miles away, though that’s still hundreds of times closer than our closest stellar neighbors. Once you get far enough into the SGL, something marvelous happens. When you look back toward the sun, any object directly behind it appears stretched out, forming a ring, and hugely magnified. That ring is the result of our star’s intense gravity, which warps space like a lens, altering the appearance of the distant object’s light.
If you position yourself correctly within the SGL, the object being magnified from behind the sun could be an intriguing exoplanet. A space telescope floating at the SGL, Turyshev explains, could then maneuver around, sampling different parts of the light ring and reconstructing the snippets of bent light into megapixel snapshots of the planet in question.
I have to interrupt him here. Did he say megapixel, like the resolution you get on your camera phone? Yes, he really is talking about an image measuring 1,000 by 1,000 pixels, good enough to see details smaller than 10 miles wide on a planet up to 100 light-years (600 trillion miles!) away.
“We could peek under the clouds and see continents. We could see weather patterns and topography, which is very exciting,” Turyshev says. He doesn’t mention it, but he doesn’t need to: That kind of resolution could also reveal megacities or other giant artificial structures, should they exist.
Assuming the JPL boffins can solve the transportation issues of getting to the SGL, the mission itself is fairly straightforward, if enormously challenging. Turyshev and his collaborators (Alkalai among them) will need to develop a Hubble-size space telescope,
or a mini-fleet of smaller telescopes, that can survive the 30-year journey. They will need to perfect an onboard artificial intelligence capable of running operations without guidance from home. Above all, they will need a target — a planet so intriguing that people are willing to spend decades and billions of dollars studying it. NASA’s TESS space telescope is doing some of that reconnaissance work right now, scanning for Earth-size worlds around local stars.
“Ultimately, to see the life on an exoplanet, we will have to visit. But a gravity lens mission allows you to study potential targets many decades, if not centuries, earlier,” Turyshev says merrily.
A journey to the SGL would take us beyond Alkalai’s baby steps, well onto the path toward interstellar exploration. It’s another audacious goal, but at least the odds of catching fire are much lower this time around.
NASA’s Mars rover Perseverance has sent pictures back to Earth of a unique rock formation within what the space agency called an “ancient lakebed” in its latest reported discovery during it mission on the Red Planet.
“Check out this patch of rock I found: looks kind of like garden pavers, and is probably exposed bedrock,” read a message from the research robot’s Twitter account on Wednesday. “Material like this, from the early days of this ancient lakebed, can help capture what that lake was like. Spending a few days investigating…”
Perseverance arrived on Mars on Feb. 18 after a six-month journey through space. The rover’s landing site was at the Jezero Crater, and “scientists believe the area was once flooded with water and was home to an ancient river delta,” according to NASA.
Check out this patch of rock I found: looks kind of like garden pavers, and is probably exposed bedrock. Material like this, from the early days of this ancient lakebed, can help capture what that lake was like. Spending a few days investigating…https://t.co/p9A2vJFjIVpic.twitter.com/0bc8lPiQLS— NASA’s Perseverance Mars Rover (@NASAPersevere) July 14, 2021
The rover is being assisted by Integrity, NASA’s Mars helicopter, which made its ninth flight on Mars earlier this month. Integrity made history on April 19 by completing the first controlled flight by an aircraft on a planet other than Earth.
“My science team is poring over these color images from the #MarsHelicopter’s latest flight,” Perseverance’s Twitter account posted last week along with video of Martian terrain. “Ingenuity crossed over a region that would be tricky for me to drive on, adding a new perspective to the picture of Jezero Crater that I’m piecing together.”
My science team is poring over these color images from the #MarsHelicopter’s latest flight. Ingenuity crossed over a region that would be tricky for me to drive on, adding a new perspective to the picture of Jezero Crater that I’m piecing together.
Making contact with probes would be better than trying to start a conversation across 100 light years of spacediverspixel/DepositphotosVIEW 34 IMAGES
August 20, 2017 marks the 40th anniversary of the launch of the the first NASA Voyager mission, which is carrying a golden record filled with messages to potential civilizations beyond our solar system. This year is also the 20th anniversary of the sci-fi film Contact that dealt with receiving radio messages from extraterrestrials. Both the record and the film were brain children of the late Carl Sagan and raise an interesting question: which approach has the greater chance of success of making contact with aliens – sending radio messages or unmanned probes?
First contact with extraterrestrial civilizations has long fascinated scientists, philosophers, and writers. It’s been the topic explored by serious scientific studies, crackpots, tabloids, science fiction epics, and international debates. The speculated results of the first meeting of man and alien run the entire gamut of imagination. Visits by aliens or receiving greetings from the stars has been seen as ranging from wonderfully transcendent, with the human race raised to the next step in evolutionary perfection, to us ending up as the main course on someone’s dinner table.
Whether the outcome is the end of 2001: a Space Odyssey or To Serve Man, how will we establish contact with whoever or whatever lives beyond our solar system? Will our first contact be an alien spaceship carrying little green men? A probe operated by an artificial intelligence? A mysterious artifact buried on the Moon? A radio signal blaring out from the stars? Zaphod Beeblebrox crashing a party in Islington?
The problem with answering this question is that we know literally nothing about any other intelligent life forms. We don’t even know if they exist or even how probable their existence is. As to how they think, their limitations, or what manner they might choose to make themselves known to us, these are questions that are so complex that it often wanders into the realm of metaphysics, if not theology.
A much easier way of reaching an answer is to ask not “How will they contact us?” but “How will we contact them?” If we can answer the latter, then we are a great deal closer to answering the former. Knowing how to send messages tells you how to receive them.
The idea of trying to contact ET is the reverse of the conventional practice of the Search for ExtraTerrestrial Intelligence (SETI). Founded in 1984, SETI is a passive search for signs of other civilizations, usually in the form of radio signals showing definite signs of intelligence, though other evidence might be sought. Deliberate contact attempts are called Active SETI or METI (Messaging to ExtraTerrestrial Intelligence), a term coined by the Russian scientist Alexander Zaitsev to denote an aggressive program of composing and sending messages to the stars.
But this idea isn’t particularly new. In fact, proposals for contacting other planetary bodies go back as far as around 1820 when the Joseph Johann von Littrow, director of the Vienna Observatory, suggested creating circles, squares and triangles 30 km on a side in the Sahara Desert by digging ditches one kilometer-wide and filling them with water topped with kerosene. This would be set alight at night in the hopes of contacting anyone on the Moon or Mars.
In 1868, inventor Charles Cros put forward a plan to the French Academy of Sciences to set up giant parabolic mirrors reflecting arc lamps with a focal length equal to the distance between Earth and Mars. Cros’ plan was to concentrate the sun’s rays on the Martian desert to carve geometric figures and numbers in molten glass on the surface. In another proposal, he suggested building an enormous checkerboard with shiny surfaces that could be uncovered to form shapes and patterns like a mechanical digital display that the Martians could view using telescopes.
In the 1890s, the Reverend W S Lach-Szyrma suggested lighting up the Riga, the Malvern Hills, or Lake Michigan with geometric patterns. Meanwhile, German mathematician Karl Friedrich Gauss recommended creating a giant right-angle triangle in Siberia using 15 km-wide strips of forest with fields of wheat as the background to form the famous geometric solution to the Pythagorean theorem. The whole thing would have been about the size of Ireland.
Not to be outdone, electrical pioneer Nikola Tesla in 1896 claimed that a more advanced version of his device for transmitting electrical power without wires could be used to contact Mars, and in 1899 he said that he’d detected signals from the Red Planet.
But perhaps the prize for the most ambitious early scheme should go to the popular science publisher and science fiction pioneer Hugo Gernsback, who in the February 1927 edition of his Radio News magazine put forward the idea of building a directional radio transmitter belting out 100,000 kilowatts in the two-meter band. True, it would have to have been a heavy bar of silver or copper glowing white hot to take all that power, but Gernsback claimed that it could not only communicate with Venus or Mars, but could also bounce radio signals off the Moon and back to Earth.
Is there anybody there?
But if we’re going to talk to other civilizations, where do we start? We start with answering a few basic questions, like is there anyone to talk to? For our purposes, we don’t need to go into all the complexities of astrobiology, planet formation or how to define the habitable zone. What we need is a rough idea of the probability of the present existence of intelligent life, how far away they are, and how advanced they are. This will tell us not only where to direct our efforts, but also when we can expect a reply, and whether they’ll understand us.
These are questions that go back to the late 1950s when the SETI field was first pioneered by Cornell scientists Giuseppe Cocconi, Philip Morrison and Frank Drake at the Green Bank radio observatory. Back then, the field was marked by swift innovation and brilliant out-of-the-box thinking because these scientists didn’t know what was possible or impossible. Many of our ideas about METI date back to this time.
One of the key tools for finding out if anyone is out there is the famous Drake Equation written in 1961, which is expressed as follows:
N = R* • fp • ne • fl • fi • fc • L
N is the number of technological civilizations in our galaxy
R* is the average rate of star formation in our galaxy
fp is the fraction of stars that have planets
ne is the average number of planets that can support life
fl is the fraction of those planets that develop life
fi is the fraction of planets with intelligent life
fc is the fraction of planets with technological civilizations
L is the lifespan of these technological civilizations
If you can find the numbers for each of these variables and plug them in, you should have a good idea of how many civilizations are out there for us to talk to. The problem is that even after almost 60 years of research, there are no reliable numbers for any of these variables. True, we know more about stellar evolution, we have discovered thousands of planets orbiting other stars and we do have a better idea of what type of planetary systems there are out there, but the specific numbers remain unknown.
The most important variable is L, which denotes the lifespan of a technological civilization. Even if all the other variables are nailed down, this one will determine the final answer. If such a civilization lasts only about a century, then we may be the only one. If they last for millions of years, there could be millions of civilizations out there. The irony is that we have no way to set L until we actually witness the rise and fall of other technological civilizations.
Our alternative is to take our only example of a planet with intelligent life (Earth) and look for somewhere that’s a relatively close match. That means looking for a single G main sequence star not too close to the galactic center and not too far on the edge. It should have a rocky planet about the size of the Earth with a large moon and sit in its star’s habitable zone.
Such a search would have been beyond our capabilities just a few decades ago, but modern exoplanet-hunting techniques have changed the game. True, nothing close to a near-Earth analog has been found (yet) and the nature of planet hunting tends toward extreme examples, but the ongoing planetary surveys have allowed us to eliminate many systems as candidates in the same way as the Mars and Venus probes put paid to any future projects to contact Venusians and Martians.
It would be nice if the Drake Equation was more tractable, because if we knew how probable another civilization was, we would know how likely it is that one was within a hundred light years of us. If it is very probable, then the probability of another civilization in our neighborhood increases. If it’s improbable, then such a civilization could be thousands or even millions of light years away, if it’s out there at all.
On the bright side, since we don’t know, we have no reason not to send our message to nearby candidate stars unless our surveys show they have no Earth-like planets orbiting them. According to some estimates, there are 19 G-type stars within 10 parsecs (32 light years) of Earth, with the nearest only four light years away, so we have some to start with. And with hundreds of million more in the galaxy, we won’t run out anytime soon.
Are aliens watching Hitler on the telly?
The next question is, how are we going to send our message? The obvious answer is radio. But it’s not a matter of pressing the mic button and starting to talk. One common misconception fostered by a certain movie is that radio communication with the stars is so easy that we’re doing it now without our knowledge. Are the inhabitants of some planet about 80 light years from Earth watching television broadcasts of Adolph Hitler opening the 1936 Berlin Olympics? Very probably not.
There are many different kinds of radio and most of them are unsuitable for communicating with the Moon, much less the stars. True, we can communicate with a deep space probe 11 billion mi (19 billion km) from Earth, but that’s because we use very powerful transmitters on Earth focusing a very tight beam, while the receivers are giant dishes precisely aimed at the transmitting spacecraft.
Other forms of radio don’t have a hope. AM transmissions simply can’t cover much distance and shortwave broadcasts bounce off the Earth’s ionosphere. As for television broadcasts, they can travel beyond our atmosphere and into deep space, as can very powerful military radars. For decades, these have been blasting out into space in a bubble that now has a radius of about a hundred light years.
At first, this makes the Earth seem like a bright radio beacon with aliens 50 light years away able to tune into Star Trek on a weekly basis. But the problem is two-fold. First, the television and similar transmissions are being broadcast in all directions, meaning that their strength is weakened by the factor of the radius squared. This means that the entire Earth from, for example, 1966 would have a brightness of 10-55 watts per square centimeter at a distance of 10 light years. That’s ten million times too faint to be detected at all, much less not be lost in all the background static. To be picked up at 100 light years, a television broadcast would need 1020 watts behind it.
It gets even worse. These broadcasts are coming from fixed spots on the Earth, which is rotating and revolving around the Sun. This makes the signals intermittent and subject to Doppler effects that distort them. Then there’s the effect of distortion by the Earth’s atmosphere, the Earth’s magnetic field, the Sun’s magnetic field, other stars, interstellar dust and gas, energetic objects, and the omnipresent cosmic microwave background radiation (CMBR) left over from the Big Bang. Add all that together and Hitler’s cosmic broadcast petered out at less than two light years.
What we are talking about here are the ultimate limits of radio communications. Despite having been at this for a little over a century, we’re already close to these limits and anyone else out there will likely be, too. This means that so long as we’re sending out electromagnetic waves, we’re likely on a level playing field no matter how advanced the other party is.
Designing the transmitter
To communicate with the stars, we need to consider three factors. First, the transmission, which must be in the form of a directed, monochromatic beam. Second, the power behind that beam must be high enough to carry information. And third, the frequency of the beam must be able to penetrate space for thousands of light years, yet have enough bandwidth to carry a message.
Ideally, the best system would be one where we design both the transmitter and receiver. Of course, we can’t do this for the first message, but there’s no reason why that message can’t include instructions on how to build a compatible receiver.
The transmitter we’d use isn’t too hard to figure out because we’ve already built several of them in the form of the radio telescopes at Arecibo in Puerto Rico, Jodrell Bank in England, and Pingtang in China, among others. To these giant dishes can be added arrays of multiple dishes, including the Very Large Array and the Allen Telescope Array.
One requirement for setting up a communication base is that it needs to be in a radio quiet zone where even mobile phone use is heavily restricted. The scene in Contact where Jodie Foster’s character is excitedly shouting orders into a walkie talkie about the message from space she’s discovered as she drives by the radio telescope dishes would have been more realistic if her colleagues at the other end angrily shouted back for her to shut up because she’s drowning out the signal.
Choosing a frequency
The next step is choosing what frequency to transmit at, which is a mixture of technical details, economy, and second guessing whoever is listening.
One premise that SETI scientists work on is astronomer Frank Drake’s Principle of Economy, which, to put it simply, is anyone we’re likely to contact will be economical and minimize the personnel, materials, and energy to achieve their ends. In other words, their bureaucrats will be as penny pinching as ours because a species that is careful with its resources will have a better survival advantage.
This means that the aliens will also assume that the frequency we choose will be the one that conserves transmitter power and costs the least energy per bit to send. At the same time, the frequency needs to be easy to generate and detect, not susceptible to much deflection, interference, or absorption by interstellar dust and gas. One other factor that helps whittle down the options is that the signal has to go through our atmosphere and we assume that the receiver is inside a similar habitable atmosphere.
Leaving out the math, the most likely band to achieve all this is between 1,000 and 10,000 MHz. The problem is that there are nine billion frequencies in this range, so which to choose? The answer is to pick one that would be recognized anywhere in the universe. SETI researchers consider two in what is called the “watering hole” as the most likely. That is the frequency of neutral hydrogen at 1,420 MHz and the Hydroxyl (OH) radical frequency at 1,721 MHz. Since Hydrogen is the most common element in the universe, and combining H with OH produces H₂O, these are most likely spots on the spectrum that someone will be listening to.
“Nature has provided us with a rather narrow band in this best part of the spectrum that seems especially marked for interstellar contact,” said leading SETI advocate Bernard Olive. “It lies between the spectral lines of hydrogen and the hydroxyl radical. Standing like the Om and the Um on either side of a gate, these two emissions of the disassociation products of water beckon all water-based life to search for its kind at the age old meeting place for all species: the water hole. Water-based life is almost certainly the most common form and well may be the only naturally occurring form.
“Romantic? Certainly. But is not romance itself a quality peculiar to intelligence? Should we not expect advanced beings elsewhere to show such perceptions? By the dead reckoning of physics we have narrowed all the decades of the electromagnetic spectrum down to a single octave where conditions are best for interstellar contact. There, right in the middle, stand two signposts that taken together symbolize the medium in which all life we know began. Is it sensible not to heed such signposts? To say, in effect: I do not trust your message, it is too good to be true.”
Lasers, neutrinos and other exotics
But radio isn’t our only option. What about lasers? We’re already experimenting with them for communication with deep space probes, and SETI researchers are looking for signs of someone else using them, too.
Lasers have many advantages. They’re tightly focused, highly directional, and monochromatic. Using an infrared beam focused by a large mirror or array, it could transmit messages at a much higher rate than a radio transmitter. Or it could be used to distort the solar spectrum by tuning the laser in to a stellar absorption band, which would look like an artificial spectral line to an alien astronomer. This would certainly gain attention and it could be made to wink on and off to send messages.
If we want to go further afield, we could use High Energy Particles (HEPs), including gamma rays, neutrinos, gravitons, and tachyons. Some are little more than theoretical, and others pose technological barriers that may never be surmounted, but they potentially have tremendous advantages.
Neutrinos, for example, would be an ideal communication medium. Sixty-five billion neutrinos emitted by the Sun pass through every square centimeter of the Earth every second and hardly any of them are stopped by the mass of the planet. If we could generate and detect them easily, they would provide us with a transmitter of unlimited range that would be almost impossible to block.
Going even farther afield, we could turn the Sun into a giant beacon by changing its spectrum directly by dumping about 400 tons of some man-made element into a heliocentric orbit. If someone light years away looked at the solar spectrum and saw something like technetium present (an element not found in nature), they’d certainly take notice. Alternatively, Philip Morrison once suggested placing opaque clouds in orbit around the Sun in a pattern that would make it seem to blink or even spell out short messages.
Oddly, one thing we don’t have to worry about for the moment are inadvertent messages. While aliens aren’t watching I Love Lucy, they could still be able to see the radio spectrum of our planet, and until recently it would have seemed very odd. Due to analog TV broadcasts and military radars, for much of the 20th century the Earth had a temperature in the radio band of the spectrum of 300 K (27° C, 80° F). In the absence of those artificial transmissions, for that to be true the Earth’s black-body temperature would need to be 40 million degrees, which is about seven thousand times hotter than the surface of the Sun.
But during the past 20 years, television has switched over to digital, which requires much smaller bandwidths, and more efficient radars have been developed, so the Earth is currently dark. But don’t get too comfortable. As we start moving out into the Solar System, there will be significant deep space traffic being tracked and tight communication beams transmitted, so things will get noisy again over the next generation.
How to write a message
So, we have our transmitter, but what do we say? To avoid the first conversation between worlds descending into awkward small talk about the weather, we need to come up with a message that’s worth listening to. More importantly, it needs to be one the recipient will understand.
It also needs to be a message that will be recognized as a message. It has to be unambiguously artificial and distinctly different from natural sources. This isn’t as easy as it sounds. A regular, repeating pattern in a radio signal may seem like an obvious beacon being transmitted by intelligent life, but radio astronomers keep being caught out by natural phenomena.
For example, on November 28, 1967, Jocelyn Bell Burnell and Antony Hewish at the Mullard Radio Astronomy Observatory in Cambridge, England observed a sequence of pulses coming at intervals of 1.33 seconds from the same point in the sky. Though a number of explanations were put forward to explain it, the idea that it might be artificial was reasonable enough for the signal to be nicknamed LGM-1, for Little Green Men.
LGM-1 turned out to be the first pulsar to be discovered, and it highlighted a problem with interstellar communications. Just because something is repeating, regular, or forms an obvious pattern, doesn’t mean there’s an intelligence behind it. Nature is filled with such things and, as the saying goes, although rare things occur rarely, it is also true that rare things occur rarely.
Imagine, as one philosopher put it, that you’re on a train from London to Cardiff. As you look out the window, you see a scattering of white stones in a field on a hillside. Is this an intelligent message? No. Stones show up in places all the time. But what if the stones form a pattern, like a series of lines or a triangle? It might be a message, but there are any number of processes that might arrange stones in an orderly manner that don’t require human intervention.
Now imagine that the stones spell out “Welcome to Wales.” Is this a message? This is much more likely because stones don’t generally form words or phrases, but it’s not outside the realms of possibility that it’s some remarkable coincidence or that we’re imposing our assumptions on what we see.
But what is the stones spell out “Welcome to Wales” and the hillside is just inside the Welsh border? Now the stones aren’t just forming a pattern, they’re expressing an actual true fact that we’re able to identify. It is a message and the probability of it being otherwise is infinitesimal.
So, if we are sending a message by radio, it has to be clearly artificial and it proves this by conveying verifiable facts that the recipient can recognize and understand. The problem is that this assumes some common frame of reference. If it hadn’t been for the Rosetta Stone repeating the same message in both Greek and Egyptian, hieroglyphics would still be as impenetrable today as they were three hundred years ago.
We need a similar Rosetta Stone and since there aren’t any monuments written in both English and Betelgeusian, we need something that is truly universal – science and mathematics.
Our cosmic message must be simple, but it must also show intelligence, so it can’t be just a repeating series of radio pulses. Instead, these pulses can be used to form binary code to convey data. It might be a series of binary numbers equivalent to 1,2,3,5,7,11 for the first prime numbers, or 1,4,9,16,25 for the first squares, or 3,1,4,1,5,9 for pi, or any of a number of other things.
This would certainly tell ET that we’re here and we’re intelligent, but our message can’t just be a string of simple numbers or it will go down as the most frustrating communication of all time. Our message has to be long. Much, much longer than these simple sequences meant as just a way to get attention. The first part might last only a couple of hours or days. The rest of the message would carry on for months.
Basically, what we’re doing is an exercise in anti-cryptology. Where a cryptographer comes up with ways to make a message harder to read or even find, we’re making one that’s as easy as possible to read, yet will still hold the reader’s attention by actually saying something worthwhile.
We could do this by splitting up the message into three types with each type alternating with the other two. To make sure we’re making up for data lost through interference or to take into account those who started listening in the middle of the message, everything would be repeated several times and perhaps on several neighboring frequencies.
The first type is made up of numbers, physical constants, arithmetic, mathematical concepts, formulae, common scientific facts, and a vocabulary. The second type would be language lessons including syntax, grammar, ideas, logic, sentences, paragraphs, and abstract concepts. Of course, this wouldn’t be in English, but more of a kind of binary Pidgin that would be intelligible to both parties.
The third type would be what we actually want to say and we’d only be limited by bandwidth and our own perseverance. We could send a very focused message, the complete sum of human knowledge in a giant encyclopedia, or we could, as the astronomer Fred Hoyle once suggested, send them instructions on how to build a computer and a copy of the software to program it with, creating a kind of electronic ambassador.
The first message
What we’ve discussed so far is what we could do if we wanted to get into some serious interstellar messaging, but it isn’t theoretical or a someday thing. In fact, Earth started sending messages into space almost half a century ago.
The first radio message to be beamed at the stars went out on November 16, 1974 using the 1,000-ft (305-m) dish antenna at the Arecibo Observatory in Puerto Rico as part of a ceremony to inaugurate a major upgrade. That day, under the eye of then-director Frank Drake, at 17:00 GMT the great dish was aimed at Messier 13 (M13) in the constellation of Hercules.
M13 is a globular cluster made up of 300,000 densely packed stars about 25,000 light-years from Earth, but it’s still within range of Arecibo, which is sensitive enough to detect a television station at a range of 1.8 light-years, BMEWS radar at 18 light-years, or its duplicate on the other side of the galaxy.
Set to 2,388 MHz, the signal shot out in a tight beam with 2 x 1013 watts behind it for two minutes and 49 seconds as 1,679 frequency pulses or bits modulated between two different frequencies to create binary code at 10 bits per second.
Unsurprisingly, 1,679 was not a number pulled out of a hat. It was very carefully chosen by Drake, who wrote the message itself before sending it to his colleague Carl Sagan to see if he could decipher it. One thousand six hundred and seventy-nine is the product of two prime numbers, 73 and 23. This is a vital clue to anyone or anything that intercepts the Arecibo Message, as it’s now known, which we’ve reproduced here.
Being the product of two prime numbers tells the recipient to set the binary numbers into a square 73 bits on one side and 23 bits on the other. There are only two ways to do this. One produces nothing but gibberish. The other forms a very low-resolution image, which is very clear if the binary ones and zeros are replaced with dark and light squares.
The Arecibo message is short, but it includes a lot of information about humans and the Solar System. The top section (colored here in white for clarity, though there is no color in the message) are the numbers one to 10 in binary with a “least significant digit” marker to show where the number begins. Below this, in purple, are the atomic numbers for hydrogen, carbon, nitrogen, oxygen, and phosphorus, which are the basic constituents of DNA.
In the next section, in green, are the formulae for the sugars and bases that make the nucleotides of DNA. These are in the form of sequences of the five elements previously described. Below this are a pair of spirals, in blue, representing the structure of DNA and a center bar, in white, that is the number 4.3 billion in binary, which is the number of nucleotides thought to make up human DNA in the 1970s.
The next section is a bit more obvious, with a stick figure, in red, in the center. Next to it is a bar, in blue, with the height of the average man represented in binary as 14 times the wavelength of the message (126 mm times 14 equals 1.7 m (5.8 ft). On the other side is the size of the human population in 1974 (4.3 billion)
Next, in the yellow, is a chart of the Solar System with a rough representation of each planet’s size. The symbol for Earth, which sits directly under the stick figure and is indented towards it to show a connection.
Finally, at the bottom of the image, is the outline of the Arecibo telescope and the binary representation of its diameter as a multiple of the message wavelength.
Because the Arecibo Message was really a stunt to show off what the telescope could do, it may have been much shorter than the ideal message we outlined above, but it still tells any recipients a lot about us. It shows a common numbering system and implies that we use a decimal system. It also tells them that we are carbon-based lifeforms, that our genetic structure is based on DNA, and something of our biochemistry. The message also shows that we’re bipeds and our size tells them something about Earth’s gravity. In addition, they know something about the structure of the Solar System and the nature of our technology.
Are we better to remain silent?
Since Arecibo, there have been about 12 other attempts to send messages to other civilizations, though none have been very long or repeated too many times. Part of the reason there have been so few and such modest attempts has been partly insufficient radio telescope time, but also the firm opposition of most of the astronomical community to sending such messages at all.
Though the idea of communicating with extraterrestrials has grown in popularity with the public, the SETI field has faced increasing difficulties in getting funding after nearly 60 years of failure, to the point where many researchers regard SETI, while laudable, as a pseudoscience without a subject and without a testable hypothesis.
According to astronomer and science fiction author David Brin, the strenuous efforts of some SETI researchers to keep the organization from being identified with UFOs and little green men has “pushed away a field that was very kind to them — bona fide science fiction” and walled in their community, isolating them from mainstream science. This has made some SETI proponents very sensitive and frustrated, leading some to advocate going straight from listening to shouting out the existence of mankind to the Cosmos in hopes of spurring a reply.
The problem is that one never knows who is going to get the message. They could be one of Sir Arthur C Clarke’s godlike, totally altruistic beings; friendly, logical Vulcans; H G Wells’ ravening Martian hordes bent on conquest; or C S Lewis’s demonic creatures motivated by pure evil. It’s this uncertainty that makes most astronomers prefer that sending any message should wait until the matter has been thoroughly discussed at the very least.
The Physicist Stephen Hawking, in an interview with the Sunday Times, said that if the human race is anything to go by, it would be better to remain silent.
“We only have to look at ourselves to see how intelligent life might develop into something we wouldn’t want to meet,” says Hawking. “I imagine they might exist in massive ships, having used up all the resources from their home planet. Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they can reach.”
Even early studies of the 1960s and ’70s said that one of the top three criteria for a civilization becoming an active transmitting one was having the technology and resources to fend off an alien invasion force or other military threats.
So does this mean that caution dictates that we never try to communicate with another civilization? Not necessarily. There is an alternative – one that we’ve already used to send messages to the stars. It’s slower than radio, but potentially much safer. This surprising competitor was actually the very first to carry a message addressed to some unknown extraterrestrial civilization years before Arecibo. The first will take tens of thousands of years to reach even the distance of the nearest star, if they ever do. Yet in this cosmic tortoise vs. hare race, it has some surprising advantages.
On March 3, 1972, Pioneer 10 lifted off from Cape Canaveral, Florida. Along with Pioneer 11, launched 11 months later, these unmanned deep space probes were tasked with making flybys of Jupiter and Saturn, setting them on a hyperbolic slingshot trajectory that made them the first spacecraft to ever set out from the Solar System, never to return.
Not wanting to pass up the opportunity to create the most audacious messages in a bottle ever tossed into infinity, NASA turned the Pioneer probes into Earth’s first cosmic emissaries by tacking a gold-anodized aluminum plaque to each one. Measuring 9 x 6 in (229 by 152 mm), these plaques were engraved with a pictogram that may one day become the most important postcard in history, if by some miracle it’s ever found.
First suggested by journalist Eric Burgess and designed and constructed in three weeks by Carl Sagan, his then-wife Linda Salzman Sagan, and Frank Drake, the plaque is the icing on the cake for Pioneer. Since the aliens will already have the inert probe to study at their leisure, the plaque’s job is to provide a bit of context as to where this mysterious spacecraft came from and who sent it.
The plaque shows the outline of the Pioneer probe, in front of which stand the nude figures of a man and a woman. The man’s hand is raised in a gesture of greeting, while the woman has one foot set slightly forward to give some idea of how humans move. Below them is a representation of the Solar System with an arrowed line showing that the Pioneer came from the third planet from the Sun. To one side is a strange diagram of spreading lines with binary symbols next to each one, while above this is a figure of two circles separated by a line.
The two humans are probably the most difficult figures to decipher, since we have no idea how much of how we see two dimensional representations is universal and how much is peculiar to us. But the rest of the plaque should give the finders the ability to deduce some basic information about us.
The two circles at the top are a schematic of the “hyperfine transition” of neutral atomic hydrogen. That is, when the spin of the electron and the proton in a hydrogen atom align shift to when they are opposed, which is when the atom emits radio waves at 1,420 MHz. Since hydrogen is universal, this fact should also be universally known.
The clever bit is that 1,420 Mhz is a wavelength of 21 cm and that gives us and the aliens a common yardstick. Underneath the line connecting the two circles is the number one in binary code. Next to the two humans is the number eight in binary, which tells the aliens that humans are 8 x 21 cm tall – a figure that is confirmed by comparing them to the height of the spacecraft drawn behind them. Since the aliens should have the probe as well as the plaque, this allows them to double check their deductions.
The Solar System diagram also includes binary numbers under each planet showing their distance from the Sun.
As to the enigmatic spider next to the humans, this is a map showing the relationship between 14 pulsars identified by binary representations of their periods, with a 15th line showing the distance between Earth and the center of the galaxy. Since the periods of pulsars are precisely measured and their rate of slowdown is also known, the aliens should be able to pinpoint the date of the probe’s launch to within 100 to 1,000 years and our position to within 60 light years. Not exactly a GPS fix, but at least it would get them close enough to find a gas station and ask for directions.
“The Pioneer plaques are destined to be the longest-lived works of mankind,” said Sagan and Drake in 1975. “They will survive virtually unchanged for hundreds of millions, perhaps billions, of years in space. When plate tectonics has completely rearranged the continents, when all the present landforms on the earth have been ground down, when civilization has been profoundly transformed and when human beings may have evolved into some other type of organism, these plaques will still exist. They will show that in the year we called 1973 there were organisms, portrayed on the plaques, that cared enough about their place in the hierarchy of all intelligent beings to share knowledge about themselves with others.”
The Pioneer message is in some ways as simple as the later Arecibo Message, but in other ways is more complex. It has only a few sections intended to convey a few pieces of information, but the resolution is higher than what could be included in a radio message and the pulsar map goes a step further by telling the recipients where and when the probe came from.
In August 1977, the next level of SETI messaging went into space with the first of the two Voyager probes. Voyager 1 and 2 were larger and more versatile spacecraft tasked with a more ambitious mission. Their trajectory not only sent them to Jupiter and Saturn, but also to Uranus and Neptune, then set them on a velocity that is sending them out of the Solar System before their predecessors.
Even 40 years later, the two spacecraft are still partially functional and will continue to operate until the nuclear power system runs out sometime between 2025 and 2030. But even after their electronics go cold, the Voyagers will still have a job as carriers of the most ambitious space message sent so far.
Mounted on the fuselage of each Voyager’s main section is the Golden Record. It’s actually a 12-in (30-cm) copper gramophone record plated in gold and sealed in a gold-electroplated aluminum cover. The latter includes an ultra-pure sample of radioactive Uranium 238, which has a half life of 4.468 billion years and provides the finder with an accurate way to calculate how much time has elapsed since Voyager left Earth. To back this up, the cover is etched with the same pulsar map found on Pioneer. Like any user-friendly product, the cover includes an operating manual showing how to use the record as well as a phonograph needle to play it.
Where Pioneer was a simple message, the Voyager record is a flat-out information dump selected for NASA by a committee led by Carl Sagan. Along with lessons in number system, units of measurements, and biochemistry, the record contains 115 images, greetings in various languages, sounds of everyday Earth life, and 90 minutes of music from around the world.
The images are stored using a simple analog technique developed in the 1920s as a way of recording television on audio records. Since television is a made up of a series of still images, this turned out to be an excellent way to store relatively high definition images. The first image is a simple circle that acts as a calibration aid for the finder.
This is followed by a solar location map; mathematical and physical unit definitions; a tutorial in human biochemistry, anatomy, and reproduction; information about the planet Earth and its structure; images of terrestrial geology, climatic regions, animal life, and plant life. There’s also a large compendium on human life, activities, architecture, eating, technology, and music, as well as printed messages from US President James Carter and UN Secretary General Kurt Waldheim.
It will be a good 40,000 years before any of these probes comes within two light years of any other star systems and odds are that none will be found for millions or even billions of years.
But what does this slowpoke approach for sending messages have over light-speed radio signals? Not much at the moment, but while we’re at the physical limits of what radio can do, interstellar travel still has a long way to go. At the moment, we’re limited to using primitive chemical rockets or ion drives that aren’t really suited to the task of jumping between the stars, but that could well change one day, if we’re patient enough.
In 1964, Soviet astronomer Nikolai Kardashev came up with a way of classifying civilizations based on how much energy they are able to harness. A Type I civilization is limited to the power available on a single planet – about 4 X 1012 joules. A Type II would be able to use the output of an entire star, which comes out to 4 X 1026 joules. Meanwhile, a Type III civilization would have the output of a galaxy at 4 X 1037 joules.
The more power a civilization has at its disposal, the more efficient it becomes. One interesting point that SETI scientists have found is that when a culture reaches the point beyond a Type I civilization, the difference in efficiency between sending radio messages and sending unmanned probes becomes negligible.
In 1960, Ronald N Bracewell of Stanford University put forward a proposal for using robotic probes rather than sending radio messages as our way of opening contact with other beings. Let’s look an updated version of his idea.
Imagine it’s a few centuries from now when the energy problems of today seem as quaint as a flint or deer antler shortage in Neolithic Britain. Humanity now has so much surplus energy at its command that sending an interstellar probe seems no more farfetched than sending a probe to Pluto does in our day.
But these are far more advanced spacecraft than any we have today. They are larger and more powerful. They are self-refueling, self-repairing, and can even duplicate themselves as required using advanced 3D printing techniques. They are also fully autonomous with computers that have an almost organic level of artificial intelligence.
These probes aren’t very fast, reaching only 10 percent of the speed of light, but they don’t have to be. With no passengers or crew, they can afford to spend a few decades or even centuries getting to their destination. As they approach the candidate star selected by mission control, each probe has the ability to study the system in detail, identify the planets most likely to possess intelligent life, and make an assessment of whether to proceed or carry on to a more promising system.
If a planet does turn out to have a civilization advanced enough to make contact with, the probe would be programmed to discretely stand off and listen to radio, television, and data transmissions. Unlike trying to pick up signals from light years away, the probe could do so from only millions of miles or might even send in scouts to orbit the planet for a closer look and listen.
Already the advantages of sending out such a system become obvious. The Bracewell probe would be intelligent enough and programmed with enough precautionary algorithms to determine if the civilization in question is safe to contact or whether it could be more in Earth’s interests to stay silent. It could even remain on station for decades or even centuries as it sends back reports to Earth.
The same watching brief might even apply if it finds a civilization that hasn’t reached a high enough level of technology to communicate with. It could patiently wait and watch as it evolves, then decide whether to communicate as soon as it starts receiving radio transmissions. Or it could leave behind an artifact, as in 2001: a Space Odyssey, that would inform Earth if it was ever disturbed, while the probe itself moves on to more productive targets. Or it might duplicate itself and send the new one on.
If the probe did decide to make contact, it would be in a far better position than someone trying to start a conversation across 100 light years of space. For one thing, the probe would have no trouble making its presence known by blasting a powerful signal at the planet, perhaps re-broadcasting television programs with a six hour delay on the same frequency as the original broadcasts to make clear that this isn’t some kind of an echo.
When contact is established, communications would be clear with a minimum of interference and responses would be received in real time. In addition, a probe orbiting the planet would have huge bandwidth at its disposal to send and receive a very large amount of data – much of it in the form of video.
It would also be a simple task for the probe to instruct the natives on how to build compatible transceivers for the most efficient exchanges or to speak directly to Earth. On the other hand, the probe could act as a gatekeeper by relaying messages to Earth and censoring information, like our location, if the indigenes prove untrustworthy.
Because the probe has artificial intelligence, it can adapt its communications to suit the recipient. It could indulge in true conversations with the natives, asking questions and being asked questions in turn as an exercise in both teaching and learning. It could even provide language lessons with suitable feedback. It might even be able to connect directly to the planet’s version of the internet and use deep learning to better understand the culture or even to communicate directly with individuals.
Indeed, these exchanges could make such a probe, in the broad sense, profitable. Instead of blasting energy into space from Earth with no known return on the investment, the probe could send its findings to Earth much more economically. In fact, unlike radio signals, an autonomous probe program would continue operate long after it had been abandoned back on Earth.
It might even act as an insurance policy for our civilization. If Earth is destroyed, then at least our culture might live on – if only as a record, albeit an intelligent record. Or the probe could be programmed with a wide sampling of the human genome and supplied with information on how to construct a biological printer that would allow it to build human cells and clone them. Scientists are already doing this with simple viruses, so it may one day be possible with Homo sapiens. It may even be possible to bioengineer the ova at code level to adapt the colonists to their new environment.
Taking things a step further, there’s no reason why the probe must be mechanical. Today, scientists are able to encode images and even videos on bacterial DNA. Perhaps, in time, some sort of microorganism could be developed with complex messages encoded on it as a form of self-replicating courier placed in small probes or turned into spores and carried on the solar winds into the galaxy. Maybe one day our first message won’t be heard over the radio, but seen through a microscope.
Today, we have a lot more experience beaming messages into deep space as our unmanned missions probe the edges of the Solar System and beyond. We know more about how to send and receive data with a minimum of wattage, how to use tight-beam radio, and how to carry out precise tracking of space objects. We’re even experimenting with laser communications in deep space and looking at new ways to send spacecraft to the nearest stars.
But whatever methods we may adopt in the future, our first messages are already on their way and we’re waiting for the reply. The odds are long, however, and we won’t hear much for about 50,000 years, so there’s time to put the kettle on.
Humans have long suspected that we are not alone in the universe, and now scientists have said there may be dozens of alien civilizations lurking not too far from Earth. Some of them may even be advanced enough to communicate with us.
According to a new study in The Astrophysical Journal, scientists at the University of Nottingham estimate that there is a minimum of 36 communicating intelligent alien civilizations in the Milky Way galaxy.
They say the estimate is actually conservative — it’s based on the assumption that intelligent life forms on other planets in a similar way to how it does on Earth, using what they call the Astrobiological Copernican Limit.The researchers assume that Earth is not special — if an Earth-like planet forms in an Earth-like orbit around a Sun-like star, hosting a civilization that develops technologically in a similar way to humans, there would be approximately 36 Earth-like civilizations in our galaxy. In this case, other technological civilizations would be sending out signals, such as radio transmissions from satellites and televisions, on a similar timeline as humans, also attempting to find other lifeforms.
“There should be at least a few dozen active civilizations in our galaxy under the assumption that it takes 5 billion years for intelligent life to form on other planets, as on Earth,” lead researcher Christopher Conselice said in a news release. “The idea is looking at evolution, but on a cosmic scale.”
Previous calculations of alien life have been based on the Drake equation, which includes seven factors needed to find the number of intelligent civilizations, written by astronomer and astrophysicist Frank Drake in 1961. The estimates have been extremely broad, ranging from zero to a few billion civilizations.
The team of researchers in Nottingham refined the equation using new data and assumptions. They found that there are likely between four and 211 civilizations capable of communicating with others, with 36 the most likely number.
Finding these civilizations is another issue entirely — scientists said they would be thousands of light years away. Our current technology makes it nearly impossible to detect or communicate with possible alien life.
Scientists said that searching for extraterrestrial intelligent life could give us insight into how long our own civilization can survive. The more civilizations we find close to home, the better the chances for humans’ long-term survival.
“If we find that intelligent life is common then this would reveal that our civilization could exist for much longer than a few hundred years, alternatively if we find that there are no active civilizations in our galaxy it is a bad sign for our own long-term existence,” Conselice said. “By searching for extraterrestrial intelligent life — even if we find nothing — we are discovering our own future and fate.”
The moon has been flashing us, and a new telescope might explain why. (Image credit: Julius-Maximilians-Universität Würzburg)
There’s something flashing us on the moon, and we don’t know what it is. But that might be about to change.
We have known about the mysterious flashes since at least the late 1960s, when the astronomers Barbara Middlehurst and Patrick Moore reviewed the scientific literature and found nearly 400 reports of strange events on the moon. Small regions of the lunar surface would get suddenly brighter or darker, without obvious explanation. The scientists’ survey of the flashes and dimming, which they called “lunar transient phenomena,” was published in the journal Science on Jan. 27, 1967. (Later, astronomers flipped the words around, terming the events “transient lunar phenomena.”)
“The emitted light is usually described as reddish or pinkish, sometimes with a ‘sparkling’ or ‘flowing’ appearance,” wrote the astronomer A. A. Mills in the March 1970 journal Nature.. “The coloration may extend for a distance of 10 miles [16 kilometers] or more on the lunar surface, with brighter spots 2 to 3 miles [3 to 5 km] across, and is commonly associated with veiling of the surface features. The average duration of an event is some 20 minutes, but it may persist intermittently for a few hours.”
Amateur astronomers can sometimes spot the flashes with the help of a decent telescope, though the flashes are unpredictable and finding one can involve hours or days of waiting.
Mills noted, bafflingly, that the events leave no obvious marks on the lunar surface after they pass.
Scientists have returned to the subject periodically in the five decades since, but without turning up conclusive explanations. These events are now known to happen a few times a week. This year, a new team of astronomers has returned to the question with an observaotry specially designed for the task.
The new instrument observes the moon constantly using two cameras located 60 miles (100 km) north of Seville in Spain. When both cameras spot a flash, according to a statement from the telescope’s designers, they record detailed photos and videos of the events, and send an email to Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, which runs the telescopes.
The observatory is still under development, according to the statement, with ongoing improvements to its software since it went online in April. Still, researchers have their suspicions as to what it will discover.
“Seismic activities were also observed on the moon. When the surface moves, gases that reflect sunlight could escape from the interior of the moon,” Hakan Kayal, a researcher at JMU and head of the telescope project, said in the statement. “This would explain the luminous phenomena, some of which last for hours.” Kayal said that, given current plans to establish a base on the moon, it’s important to know just what’s going on up there, so folks living at the base can be prepared for their environment.
But even if that base never happens, it would be nice to know why the moon keeps flashing us.
The moon doesn’t lose a lot of staring contests.
But every now and then, Earthlings who train telescopes on the natural satellite get a a real eye-opener: the moon blinks back at them.
A light, often red or pink, may suddenly flash from the darkness. It lasts a mere second. Other times, the seemingly random twinklings go on for hours.
Is it Morse code? Is someone stranded up there? What are you trying to tell us, Man on the Moon?
Scientists have a name for the effect — transient lunar phenomenon, or simply,TLP. But they don’t know much else. Despite flashing moon lights being recorded for decades, scientists remain as baffled as ever about their origin.
Is there a method to those pulses of light, often emanating from several points of the moon at once? Theories range from meteorites pelting the moon to gasses being vented from deep beneath the surface.
But astronomer Hakan Kayal may have solved this riddle once and for all by literally connecting the dots.
Kayal, a professor at Germany’s University of Würzburg, built a moon telescope, deploying it in Spain earlier this year. From its rural base north of Seville, the telescope is mostly free from meddling light pollution, allowing its unflinching eye to remain fixed on the moon.
Make that two eyes. The telescope incorporates dual cameras, each remotely operated from the university campus in Bavaria. When those cameras detect a burst of light, they automatically start recording images, while sending an email to the German research team: The moon is doing that thing again.
But the real sleuthing will be done by software. Kayal’s team is still honing an AI system that will be able to zero in on flashes of light that originate strictly from the moon.
But once the lunar telescope’s AI is trained to tune out distractions — it’s expected to be ready in about a year — Kayal says it will be fully tuned into TLP, recording the moon’s every twinkling outburst.
Software Improvements Needed
“One main task for us is to further develop our software for the detection of the events with as low false alarm rates as possible,” Kayal tells Popular Science. “We already have a basic version which works but there are improvements necessary. As the project is not third party-funded yet and only funded by the resources of the university itself, there is not very much manpower for the software. But we have students who can help to improve the software within their study.”
Once those dots are connected, scientists may, for the first time, be able to analyze patterns and come up with a credible theory for that baffling lunar light show.
For now, Kayal has one of his own:
“Seismic activities were also observed on the moon,” he suggests in a press release. “When the surface moves, gases that reflect sunlight could escape from the interior of the moon. This would explain the luminous phenomena, some of which last for hours.”
VVV-WIT-08, Giant Blinking Star, Spotted by Astronomers Near Milky Way
An international team of astronomers has spotted a giant ‘blinking’ star towards the centre of the Milky Way, more than 25,000 light years away. The star, VVV-WIT-08, decreased in brightness by a factor of 30, so that it nearly disappeared from the sky.
London, June 11: An international team of astronomers has spotted a giant ‘blinking’ star towards the centre of the Milky Way, more than 25,000 light years away. The star, VVV-WIT-08, decreased in brightness by a factor of 30, so that it nearly disappeared from the sky. While many stars change in brightness because they pulsate or are eclipsed by another star in a binary system, it is exceptionally rare for a star to become fainter over a period of several months and then brighten again, the team said.
The researchers believe that VVV-WIT-08 may belong to a new class of “blinking giant” binary star system, where a giant star 100 times larger than the Sun is eclipsed once every few decades by an as-yet unseen orbital companion.
The companion, which may be another star or a planet, is surrounded by an opaque disc, which covers the giant star, causing it to disappear and reappear in the sky. The study is published in Monthly Notices of the Royal Astronomical Society.
“It’s amazing that we just observed a dark, large and elongated object pass between us and the distant star and we can only speculate what its origin is,” said Sergey Koposov from the University of Edinburgh.
Since the star is located in a dense region of the Milky Way, the researchers considered whether some unknown dark object could have simply drifted in front of the giant star by chance. However, simulations showed that there would have to be an implausibly large number of dark bodies floating around the galaxy for this scenario to be likely.
One other star system of this sort has been known for a long time. The giant star Epsilon Aurigae is partly eclipsed by a huge disc of dust every 27 years, but only dims by about 50 per cent. A second example, TYC 2505-672-1, was found a few years ago, and holds the current record for the eclipsing binary star system with the longest orbital period — 69 years — a record for which VVV-WIT-08 is currently a contender.
The UK-based team has also found two more of these peculiar giant stars in addition to VVV-WIT-08, suggesting that these may be a new class of “blinking giant” stars for astronomers to investigate. There now appear to be around half a dozen potential known star systems of this type, containing giant stars and large opaque discs.
If there is one misguided theme I have heard repeated many times in and outside of the UFO community, it is the notion that UFOs and extraterrestrials are our benevolent technological and spiritual superiors, who are only trying to watch over us and gently guide human kind from a path of nuclear, biological and ecological self-destruction to an interstellar highway of spiritual enlightenment and prosperity.
This mantra has been repeated ad nauseum ever since the first UFO was sighted and close encounter was experienced. Yet, there is much documented evidence that these aliens, extraterrestrials or inter-dimensional interlopers may not always be benevolent. On the contrary, there is much more proof that these uninvited guests, who boldly penetrate our airspace, have at times kidnapped, injured and killed innocent humans and animals.
Thankfully, this wasn’t the case in the latest, solidly documented close-encounter case recorded in a recently released Pentagon UFO study. The usually mum Department of Defense almost appeared eager to report the Nov. 14, 2004 UFO incident, experienced by former Navy pilot David Fravor, who repeated a familiar story to all of us who have studied the history of Ufology the last 70 years. While flying a routine mission off an aircraft carrier he and other pilots spotted a UFO that made incredibly sharp turns and reached speeds impossible for aircraft using Earth’s technology. As he watched this mystery craft zip away at an extremely high speed, he came to the same conclusion many of his fellow, military pilots have come to: “It was not of this world,” Fravor told various news organizations. He added that no human could have possibly withstood the G force of such a tremendous thrust of sudden acceleration.
In this concise report, I will present to you documented evidence of a pilot unlike Fravor, who suffered harm in such a mysterious encounter. Such incidents are vastly under reported. For example, until I really started researching this subject, I never realized that a U.S. Army pilot became the first known casualty as a result of such UFO aggression. Although the Army denied this, and summarily covered up this horrifying event with no less than three different, ever- morphing cover stories, I will present you with documentation and eyewitness accounts from credible witnesses that prove within a reasonable doubt that on a January afternoon in 1948 hostile extraterrestrials committed an act of war against the United States. It was likely not the first – and certainly – will not be the last.
I will also present evidence that proves that the population of a small island was terrorized and its impoverished residents used as guinea pigs by an alleged flap of UFOs that harassed and injured scores of innocent men and women for a period of months. Some of these unfortunates still carry the scars from burns and wounds that were inflicted upon them by these unknown perpetrators. The proof consists of eyewitness accounts and secret documents that have been leaked out over several decades. Additionally, in this report, I will document numerous cases of aggressive and hostile UFO acts taken against both military and commercial pilots.
As a bonus, I have also included many little known UFO sighting reports from the early 1860’s to the present. Even though some of these are not directly hostile encounters, all of them invaded our airspace and in some cases crash landed, exposing humans to potential injury or death. Plus, I will present documentation of ongoing cattle mutilations that remain a dark mystery but point to either nefarious government and alien culprits — or a collaboration of both. In conclusion, I must warn you that some will not like this report. They will categorize my conclusions as alarmist and sensational. But as always, I leave it up to you the reader to decide.
A recently-discovered declassified Australian report analyzes 1,000 UFO encounters of the third kind to understand the kinds of weapons being used against humans and their animals by these visitors — and if they are being used defensively or without provocation. The reports of UFO landing and near landings were complied by the renowned Ufologist and physicist Jacques Vallee, who worked with the late and honorable Professor Hynek. Hynek acted as scientific advisor to UFO studies undertaken by the U.S. Air Force under two projects: Project Sign and Project Blue Book.
3 Weapon Systems
After a thorough analysis of the 1,000 UFO cases from around the world, the report found the existence of three “weapon systems being used by these unidentified visitors:”
a device to interfere with electrical circuits.
a device to induce paralysis.
a heat ray.
Visitors Use of Weapons The report, which is dated January 1970, sums up the use of weapons by the alleged extraterrestrials against humans and animals in the following manner:
“There is circumstantial evidence that these weapons are at times used deliberately, although mostly in a defensive role. A number of reports allege that a lone car at night has been followed, and after being stopped by a beam, some kind of interaction has developed between the car occupants and the landed craft occupants.
Information is included which deals with residual effects on the environment of the landed craft. It is these residual effects which offer the greatest potential reward to scientific investigation at this stage.
Sampling of 1,000 Cases Analyzed
Here is a sampling of the 1,000 documented cases. As of this writing, the entire 12-page report, can still be read on the National Archives of Australia, but the PDF download feature is currently disabled.
Case #234 France: 3 small humanoids by craft 50 meters away. Small, reddish point of light. Both witnesses paralyzed until craft left. Ignition failure.
Case #249 France: Witness reach 20 meters from dish with 4-foot being in diving suit before being paralyzed. As craft took off, witness thrown to ground.
Case #272 France: Horse lifted [by]10 foot by 5 foot diameter object and was paralyzed 10 minutes. Man at side of horse felt nothing.
Case #279 France: Dog partially paralyzed when approached two helmeted figures near dome.
Case #295 Italy: 4-foot-3-inch being by tree aimed a flashlight beam, paralyzing witness. Action of clenching fist on keys freed him allowing him to attack the intruder who flew away with a soft whir on a conical device.
Case #339 Italy: 3 small humanoids stealing rabbits from cage. Farmer aims rifle which fails to fire and then has to be dropped.
Case #356 Venezuela: Witness came across 6 little men loading boulders into hovering dish. As he started to run away, one of the creatures pointed something at him which gave off a violet-colored light and paralyzed him.
Case #398 Argentina: Dish lands. Air Force man unable to draw gun from holster. Voice in Spanish from craft.
Case #400 Brazil: Man fell paralyzed. Companions see dish with dome top and bottom 50 meters away. Three 5-foot-7-inch men gather samples.7/11/2021 Declassified Australian Report Analyzes Weapons UFOs Use Against Humans – Unknown Boundaries
Case #333 France: Blue dish came close to motorcycle; prickling felt in hand, engine dies and unable to move of speak. They blue light turns off, all o.k.
Again, this is just a sampling, the entire report can be read here, as of this writing. * Sometimes such documents mysteriously disappear. I made jpeg copies, for myself, however, this is a labor-intensive method. But it’s better to be safe than sorry.
Here are copies of the documents I used for this post:
A new study sheds light on the final supernovae of the Universe.
The supernova remnant Cassiopeia A.Credit: NASA/JPL-Caltech/STScI/CXC/SAOA physicist calculated when and how the final explosions in our universe will take place.Matt Caplan of Illinois State University predicts black dwarfs will go supernova in the distant future.About a billion trillion stars will meet this end.
What will the end of the universe look like? A new study shows a series of black dwarf explosions might be the final coda in its story.
Matt Caplan, the theoretical physicist from Illinois State University who conducted the study, says the end-times universe will be “a bit of a sad, lonely, cold place.” Most scientists expect not much will be around to witness the proceedings of this “heat death” – just black holes and burned-out stars. But Caplan also sees something else happening then.
As the universe functions now, massive stars die in supernova explosions that follow an over-accumulation of iron in their cores. The smaller stars meet their demise by burning through all their nuclear fuel and turning into white dwarfs. Caplan’s research shows that as these space objects proceed to cool over trillions of years, they will dim completely, freeze into solids and become “black dwarfs.” These super dense stellar bodies will contain mostly elements like carbon and oxygen and will be the size of Earth while having as much mass as the sun.
Caplan thinks that even though these stars will be burned out, slow fusion reactions will still take place, producing iron, which will eventually lead to explosions. The scientist calculates just how long these black dwarfs have before their supernovas in a future world filled with “sparse degenerate remnants,” as he calls them in his paper.
The first of these final booms of our universe will take place about 10 ^1100th years from now. “In years, it’s like saying the word ‘trillion’ almost a hundred times,” explains Caplan, pointing out that “If you wrote it out, it would take up most of a page. It’s mindbogglingly far in the future.”
He doesn’t anticipate that all black dwarfs would end up exploding, just the most massive ones, with the mass of about 1.2 to 1.4 times the mass of the sun. That means about 1 percent of the of stars that exist today will meet this eventuality. That’s about a billion trillion stars, if you’re counting. The rest will stay as black dwarfs.
What is a Black Dwarf?
Caplan expects our sun won’t end up in a supernova either as it doesn’t have enough mass to explode.
When will all the final explosions stop, turning out universe into a dark, silent graveyard of cosmic shards? In about 10^32000 years.
“It’s hard to imagine anything coming after that, black dwarf supernova might be the last interesting thing to happen in the universe,” he shared. “They may be the last supernova ever.”
The truth is our there, if you know what you’re looking for…
In the search for extraterrestrial intelligence (SETI), we can’t simply point our telescopes out to the cosmos and hope to stumble across an alien civilisation. We need to know exactly what we’re looking for. The good news is that just as astrobiologists have a catalogue of tell-tale signs of life on other planets called biosignatures, SETI researchers have their own list of things that would indicate the existence of intelligent life beyond Earth. These are known as “technosignatures”.
SETI began in earnest in 1960 with Project Ozma, when Frank Drake used the Green Bank Telescope in West Virginia to search for artificial radio signals around two stars. The idea was that any alien transmissions would be identifiable because, like ours, they would look different to natural sources of radio waves. Since then, most searches have focussed on radio signals. And although most sightings have proved red herrings, including the famous Wow! Signal, this strategy is still throwing up some of the most promising candidates.
Around the same time as astronomers began scouring stars for radio signals, the physicist Freeman Dyson suggested another potential technosignature. Dyson reasoned that to satisfy its ever-increasing energy needs, an advanced alien civilisation would build an enormous solar power plant around its host star. This would heat up and generate an infrared glow in excess of what you would expect from an unadorned star – a glow that we could see from Earth.https://2c088916de0eb4f6fde39cec0c70e5f0.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html
These hypothetical megastructures are now known as Dyson spheres. Searching for them remains a minority sport, but some researchers have recently begun to step up the hunt by figuring out how to distinguish a genuine Dyson sphere from a star shrouded in dust.
Any advanced extraterrestrial civilisation is likely to have transformed its host planet with industry. SETI researchers have proposed that we could look for their non-natural waste products such as chlorofluorocarbons (CFCs), which can persist in the atmosphere for tens of thousands of years. Astrophysicist Avi Loeb of Harvard University has also suggested light pollution on the night side of an extrasolar planet as a possible sign of technological civilizations.
Any advanced civilisation runs the risk of destroying itself, and the fallout might be visible to distant observers. Nuclear bombs would release flashes of gamma rays, but they would be fleeting and the resulting dust would be hard to distinguish from that produced by an asteroid strike.
Tantalising evidence has been uncovered for a mysterious population of “free-floating” planets, planets that may be alone in deep space, unbound to any host star. The results include four new discoveries that are consistent with planets of similar masses to Earth, published today in Monthly Notices of the Royal Astronomical Society.
The study, led by Iain McDonald of the University of Manchester, UK, (now based at the Open University, UK) used data obtained in 2016 during the K2 mission phase of NASA’s Kepler Space Telescope. During this two-month campaign, Kepler monitored a crowded field of millions of stars near the centre of our Galaxy every 30 minutes in order to find rare gravitational microlensing events.
The study team found 27 short-duration candidate microlensing signals that varied over timescales of between an hour and 10 days. Many of these had been previously seen in data obtained simultaneously from the ground. However, the four shortest events are new discoveries that are consistent with planets of similar masses to Earth.
These new events do not show an accompanying longer signal that might be expected from a host star, suggesting that these new events may be free-floating planets. Such planets may perhaps have originally formed around a host star before being ejected by the gravitational tug of other, heavier planets in the system.
Predicted by Albert Einstein 85 years ago as a consequence of his General Theory of Relativity, microlensing describes how the light from a background star can be temporarily magnified by the presence of other stars in the foreground. This produces a short burst in brightness that can last from hours to a few days. Roughly one out of every million stars in our Galaxy is visibly affected by microlensing at any given time, but only a few percent of these are expected to be caused by planets.
Kepler was not designed to find planets using microlensing, nor to study the extremely dense star fields of the inner Galaxy. This meant that new data reduction techniques had to be developed to look for signals within the Kepler dataset.
Iain notes: “These signals are extremely difficult to find. Our observations pointed an elderly, ailing telescope with blurred vision at one the most densely crowded parts of the sky, where there are already thousands of bright stars that vary in brightness, and thousands of asteroids that skim across our field. From that cacophony, we try to extract tiny, characteristic brightenings caused by planets, and we only have one chance to see a signal before it’s gone. It’s about as easy as looking for the single blink of a firefly in the middle of a motorway, using only a handheld phone.”
Co-author Eamonn Kerins of the University of Manchester also comments, “Kepler has achieved what it was never designed to do, in providing further tentative evidence for the existence of a population of Earth-mass, free-floating planets. Now it passes the baton on to other missions that will be designed to find such signals, signals so elusive that Einstein himself thought that they were unlikely ever to be observed. I am very excited that the upcoming ESA Euclid mission could also join this effort as an additional science activity to its main mission.”
Confirming the existence and nature of free-floating planets will be a major focus for upcoming missions such as the NASA Nancy Grace Roman Space Telescope, and possibly the ESA Euclid mission, both of which will be optimised to look for microlensing signals.
Nikola Tesla was undoubtedly one of the brightest minds of the 20th century. Many of our modern day commodities owe their existence to his brilliant mind. However, he lived most of his life in a constant battle with the energy brokers of his day, namely Thomas Edison backed by General Electric.
On January 7, 1943, Tesla died alone and impoverished in room 3327 of the New Yorker Hotel. Two days after his death, the FBI ordered that all of his belongings be seized.
His lifetime work was confiscated by the Office of Alien Property even though he had been an American citizen for 52 years. It was known at the time that Tesla had been working on several important projects, including wireless communications and limitless free energy.
Tesla’s plan was to harness energy from the radiation present in the universe, using the entire planet as a conductor. This would have meant that anybody could have free electricity simply by sticking a metal rod into the ground.
These notions did not go well with the power elite, whose interest was maintaining the status quo, that is keeping their multi-billion dollar businesses running.
After all, what good was free energy if they wouldn’t be able to meter and control it? Therefore, many speculate that the U.S. government acted according to the pressure exerted by these big corporations. They eventually shipped his estate to Belgrade, Yugoslavia but not before taking nine years to go through it.
This situation gave rise to a pervasive notion that is strongly supported by circumstantial evidence: Tesla’s research was considered critical, even dangerous and was confiscated for good measure.
His ideas could have constituted an important advancement for humanity and that’s exactly why they were withheld.
It is believed that the technology behind HAARP is based on Tesla’s research. The U.S. has many top-secret compounds around the world and also has a history of secretly developing technology.
Perhaps this is why Tesla’s papers were seized but we might never know for sure.
After years of fielding questions about possible cover-ups, the FBI finally declassified some 250 pages of Tesla-related documents under the Freedom of Information Act in 2016. The bureau followed up with two additional releases, the latest in March 2018.
But even with the publication of these documents, many questions still remain unanswered—and some of Tesla’s files are still missing.
Shortly after an electrical engineer, Dr. John G. Trump (yes it is current President Donal Trump’s uncle) was assigned to review his papers to discover if any of it was of actual tangible value.
He determined that it was “primarily of a speculative, philosophical and promotional character” and said the papers did “not include new sound, workable principles or methods for realizing such results.”
Tesla’s extended family, including his nephew Sava Kosanovic, tried desperately to have at least his personal effects returned. Their requests were eventually accepted and some of his personal items were returned to the family.
Recently declassified documents reveal that the FBI, at the time, were concerned with his nephew’s intentions. They had even considered arresting him to prevent Tesla’s work falling into enemy hands.
After a long court battle, Kosanovic, the rightful heir to his uncle’s belongings, was finally given them. Tesla’s possessions and files were sent to Belgrade.
But, interestingly, of the 80 trunks or so of Tesla’s effects, only 60 arrived in Belgrade. Whether the U.S. Government had kept some of the information and effects or not is still, today, unknown.
It is also believed that Ronald Reagan’s “Star Wars” Strategic Defense Initiative program in the 1980s was probably inspired by Tesla’s “Death Ray”. But if the government is still using some of Tesla’s material for its Research and Development, this would explain why some, if any, of his original works, are still missing today.
A new clue has just been found that could help solve the mystery of a weirdly dimming star. KIC 8462852, also known as Boyajian’s Star, seems to have a binary companion that could be contributing to its irregular dips in brightness.
If confirmed with more detailed observations, the newly discovered companion star could help astronomers finally solve KIC 8462852’s ongoing mystery.
The star was discovered in 2015 by astronomer Tabetha Boyajian (hence it was previously Tabby’s Star), and since then it has proven to be a real puzzle. It’s a yellow-white dwarf star around 1,470 light-years away, and it keeps dimming erratically. There is no regularity either to the timing of the star’s dimming, or the depth – some of the dips in starlight have been as deep as 22 percent.
This behaviour rules out planets; when an exoplanet passes between a star and Earth as it orbits, it will dim the star by a tiny amount – 1 percent or less – at regular intervals.
Furthermore, when Boyajian’s Star dims, some wavelengths are blocked more than others. That rules out a solid object (such as an alien megastructure, as proposed in 2016), which would block all wavelengths equally.
So far, the most likely explanation seems to be optically thin dust and debris, possibly from broken-up planetesimals or comets on eccentric orbits, in combination with normal brightness variations from the star itself.
The presence of a binary companion star on a wide orbit could help explain the presence of all this material, providing additional gravitational perturbations to disrupt orbiting bodies.
Since 2016, a team of astronomers led by Logan Pearce of the University of Arizona has been trying to confirm the potential connection of a nearby star to KIC 8462852. Their paper has now been accepted into The Astrophysical Journal.
The difficulty of measuring space in three dimensions is what’s made this work rather hard. Stars that look quite close together might actually be at wildly different distances from the viewer. So, Pearce and team used five years’ worth of observations to make precise astrometric measurements of the faint star that seemed close to KIC 8462852.
“In this work we use three epochs of Keck/NIRC2 astrometry spanning five years to revisit the status of the close companion to KIC 8462852, and show that they are a common proper motion pair and a gravitationally bound binary system,” they wrote in their paper.
In addition to the Keck Observatory observations, the 2020 release of astrometric data from the Gaia satellite – the most complete and precise three-dimensional map of the Milky Way to date – also included the faint star, with measurements in agreement with the team’s findings.
The two stars are separated by a distance of 880 astronomical units. Boyajian’s Star, or KIC 8462852 A, is the bigger star, at around 1.36 times the mass and 1.5 times the size of the Sun. The companion, KIC 8462852 B, is a red dwarf star around 0.44 times the mass and 0.45 times the size of the Sun.
At such a wide orbit, KIC 8462852 B would be unlikely to have any direct effect on the brightness of KIC 8462852 A. But it could still play a role in the larger star’s mystery fluctuations, the researchers said.
Scientists have previously found that widely spaced stellar binaries can be pushed by larger gravitational forces to move in very close to their mutual centre of mass multiple times over the course of around 10 billion years.
In turn, this could result in the disruption of planets and other small orbiting bodies where they’re stretched and torn apart by gravitational interactions, resulting in clouds of debris.
The scenario is yet to be confirmed. At such a wide separation, the two stars would have an extremely long orbit, and the observations taken were not sufficient to characterise this orbit. KIC 8462852 B could be a star that was ejected from the system; or the two stars could be members of a co-moving group.
The researchers believe that a binary is the most likely explanation for their measurements of the two stars, but future measurements of the pair will be needed to better understand their relationship. This could help confirm or rule out KIC 8462852 B’s role in the star’s erratic brightness.
An unseen threat might come from deep space in the future.
#space #earth #asteroid #supernova
DANGER ZONE. Many dark objects lie too far from the Sun to be observed. An unseen threat might come from deep space in the future.
Although we live in relative quiet within the cosmos, going about our lives and seeing the stars as a distant backdrop, we are very much part of the universe that surrounds us. Dangers lurk in space, as any glance at the Moon’s cratered surface confirms.
Not only must our planet avoid collisions with Earth-crossing asteroids, but more remote threats exist. If a nearby star went supernova, a gamma-ray burst erupted nearby, or a black hole or stream of antimatter somehow wandered into our neighborhood, it could spell disaster. While astronomers say those events are unlikely, another dark, distant interloper could create havoc on Earth by its mere presence.
Where could such trouble come from? The Sun hasn’t always been a solitary star. It was born in a group of suns, as all stars are, and its native companions have been scattered by the gravitational tug created by orbiting the galaxy’s center.
Yet some 5 billion years after the Sun’s birth, a few of its associates still linger near the old neighborhood. Among them are the Sun-like star Alpha (α) Centauri, the yellowish dwarf Tau (τ) Ceti, and the cool red dwarf Wolf 359. Is the Sun truly single, or could a cool, dark companion loom in the background, periodically nudging comets toward Earth?
The discovery of Sedna, a trans-Neptunian object found in 2003, and the subsequent discovery of Eris, fueled the idea that large, dark bodies float in the solar system’s distant reaches. Those bodies exist apart from the numerous comets that populate the Oort Cloud. Close passages of well-known stars will occur far on down the line: For example, in less than a million and a half years, Gliese 710, a red dwarf now 60 light-years away, will slide within a light-year of the Sun. This will unleash a torrent of comets from the Oort Cloud into orbits that could intersect Earth’s, and they will arrive near our planet within a liberal span of about 2 million years.
But bombings from comet nuclei could result from other sources, too. A number of astronomers suggest the Sun may have a hidden, dark companion that periodically sends comets sunward, raining them down on the inner solar system.
UNSEEN COMPANION. A small dim object called a brown dwarf could orbit the Sun in our solar system’s distant regions. Brown dwarfs fall somewhere between the smallest star and the largest planet. This artist’s conception shows a pair of brown dwarfs.NASA/ESA/A. Feild (STScI)
In 1984, University of Chicago paleontologists David Raup and J. John Sepkoski revealed their finding that Earth’s extinction events were periodic. At the time, they suggested the Sun’s orbit about the Milky Way’s center was responsible, unleashing comets at regular intervals of about 26 million years.
In the same year, University of California, Berkeley, physicist Richard Muller proposed the responsible mechanism was “Nemesis,” an unseen, distant stellar companion to the Sun. Muller thought an M dwarf — a small, cool star — could lurk unnoticed in the distance yet have a huge effect on the Oort Cloud. about:blank
With the advent of the Two Micron All-Sky Survey (2MASS), however, astronomers scoured the whole sky at near-infrared wavelengths, producing 2 million images that would have uncovered Nemesis, had it existed. So the mystery of what lurks out in the darkness beyond the Oort Cloud, if anything, continues.
Not all scientists are unconcerned about the idea of a dark threat. Michael Rampino, a geologist at New York University, searches for an astronomical object he believes may be responsible for recurring extinction events every 25 to 35 million years.
As suggestive evidence, Rampino employs the large-impact events that produced craters under the Chesapeake Bay between Virginia and Maryland and in Popigai, Siberia, about 35 million years ago and the K-T impact in the Yucatán Peninsula, the “dinosaur-killer” that occurred 65 million years ago. Rampino believes several smaller lines of evidence suggest another catastrophic impact 95 million years ago.
If a dark monster is out there, it could be a small brown dwarf. If such a starlet exists, it might weigh less than 40 Jupiter masses, making it slip under the radar of the 2MASS survey. It would have a highly elliptical orbit that would make it hard to spot because most of its time would be spent far from us. Still, most astronomers remain skeptical. Only time will tell.
Do atoms going through a double slit ‘know’ if they are being observed?
#physics #quantum #reality #atoms
Does a massive quantum particle – such as an atom – in a double-slit experiment behave differently depending on when it is observed? John Wheeler’s famous “delayed choice” Gedankenexperiment asked this question in 1978, and the answer has now been experimentally realized with massive particles for the first time. The result demonstrates that it does not make sense to decide whether a massive particle can be described by its wave or particle behaviour until a measurement has been made. The techniques used could have practical applications for future physics research, and perhaps for information theory.
In the famous double-slit experiment, single particles, such as photons, pass one at a time through a screen containing two slits. If either path is monitored, a photon seemingly passes through one slit or the other, and no interference will be seen. Conversely, if neither is checked, a photon will appear to have passed through both slits simultaneously before interfering with itself, acting like a wave. In 1978 American theoretical physicist John Wheeler proposed a series of thought experiments wherein he wondered whether a particle apparently going through a slit could be considered to have a well-defined trajectory, in which it passes through one slit or both. In the experiments, the decision to observe the photons is made only after they have been emitted, thereby testing the possible effects of the observer.
For example, what happens if the decision to open or close one of the slits is made after the particle has committed to pass through one slit or both? If an interference pattern is still seen when the second slit is opened, this would force us either to conclude that our decision to measure the particle’s path affects its past decision about which path to take, or to abandon the classical concept that a particle’s position is defined independent of our measurement.
While Wheeler conceived of this purely as a thought experiment, experimental advances allowed Alain Aspect and colleagues at the Institut d’Optique, Ecole Normale Supérieure de Cachan and the National Centre for Scientific Research, all in France, to actually perform it in 2007 with single photons, using beamsplitters in place of the slits envisage by Wheeler. By inserting or removing a second beamsplitter randomly, the researchers could either recombine the two paths or leave them separate, making it impossible for an observer to know which path a photon had taken. They showed that if the second beamsplitter was inserted, even after the photon would have passed the first, an interference pattern was created.
The wave–particle duality of quantum mechanics dictates that all quantum objects, massive or otherwise, can behave as either waves or particles. Now, Andrew Truscott and colleagues at Australian National University carried out Wheeler’s experiment using atoms deflected by laser pulses in place of photons deflected by mirrors and beamsplitters. The helium atoms, released one by one from an optical dipole trap, fell under gravity until they were hit by a laser pulse, which deflected them into an equal superposition of two momentum states travelling in different directions with an adjustable phase difference. This was the first “beamsplitter”. The researchers then decide whether to apply a second laser pulse to recombine the two states and create mixed states – one formed by adding the two waves and one formed by subtracting them – by using a quantum random-number generator. When applied, this final laser pulse made it impossible to tell which of the two paths the photon had travelled along. The team ran the experiment repeatedly, varying the phase difference between the paths.
Truscott’s team found that when the second laser pulse was not applied, the probability of the atom being detected in each of the momentum states was 0.5, regardless of the phase lag between the two. However, application of the second pulse produced a distinct sine-wave interference pattern. When the waves were perfectly in phase on arrival at the beamsplitter, they interfered constructively, always entering the state formed by adding them. When the waves were in antiphase, however, they interfered destructively and were always found in the state formed by subtracting them. This means that accepting our classical intuition about particles travelling well-defined paths would indeed force us into accepting backward causation. “I can’t prove that isn’t what occurs,” says Truscott, “But 99.999% of physicists would say that the measurement – i.e. whether the beamsplitter is in or out – brings the observable into reality, and at that point the particle decides whether to be a wave or a particle.”
Indeed, the results of both Truscott and Aspect’s experiments shows that a particle’s wave or particle nature is most likely undefined until a measurement is made. The other less likely option would be that of backward causation – that the particle somehow has information from the future – but this involves sending a message faster than light, which is forbidden by the rules of relativity.
Aspect is impressed. “It’s very, very nice work,” he says, “Of course, in this kind of thing there is no more real surprise, but it’s a beautiful achievement.” He adds that, beyond curiosity, the technology developed may have practical applications. “The fact that you can master single atoms with this degree of accuracy may be useful in quantum information,” he says.
A leading expert on planetary astronomy reflects on what the next generation of space telescopes might reveal.
When I look up at the stars, I love to wonder what kind of planets might be around each one. Every star is a sun, and astronomers have found thousands of planets orbiting other stars, called exoplanets. Perhaps there are intelligent beings on a distant planet, looking back at our sun—a star to them—wondering the same thing.
We astronomers are unabashedly anticipating a paradigm shift in exoplanet characterization—made possible by a sophisticated new telescope over 30 years in the making: the James Webb Space Telescope, set for launch this October. Webb will undergo a series of daunting deployments, including the unfurling of a tennis court-sized, five-layer sunshield before reaching its destination a million miles away from Earth. Thousands of astronomers all around the world have pinned their research hopes and dreams on Webb, not just for exoplanets but for many frontier topics in astronomy. But for those of us studying exoplanets, Webb will open a new window.
Webb will bring us our first chance to routinely observe small rocky exoplanet atmospheres. Atmospheric water vapor would indicate the presence of surface liquid water oceans—key because a liquid solvent is needed for life. Imagine: Soon we may know that rocky planets with liquid water exist and are common—implying that habitable worlds might be all around us. Even more compelling is the chance to identify atmospheric gases that might be attributed to life, called biosignature gases. For example, molecular oxygen fills Earth’s atmosphere to 20 percent by volume but is so highly reactive it should not be present at all, without continual replenishment—in this case, by plants and photosynthetic bacteria. If molecular oxygen appeared in the atmosphere of a small rocky exoplanet, we would likewise assume that some process is at work there to continually replenish it. Admittedly, getting a strong robust signal from small exoplanet atmospheres might be tough for Webb, possibly right at the edge of its capabilities. True Earth twins—those Earth-size planets in Earth-like orbits about stars like our sun—are completely out of this telescope’s reach.
Instead, Webb’s ultimate lottery ticket is one of the handful of small planets transiting small red dwarf stars. Such planets orbiting in the “Goldilocks zone” will be different from Earth: locked into a rotation rate that causes a permanent day and permanent night side and bombarded by intense high-energy radiation from frequent stellar flares.
We may have already found a biosignature gas right next door, on our sister planet Venus. Venus, with its scorching surface so hot no life of any kind could survive, seems an unlikely abode. But a cloud-filled layer well above the surface does have a suitable temperature for life. The cloud environment is very harsh—highly acidic and incredibly dry—nonetheless, people have speculated about life in the Venus clouds for more than half a century.
I was part of a team led by Professor Jane Greaves that recently reported the detection of phosphine gas from radio telescope observations of Venus. We calculated that no known chemical process—from volcanoes to lightning to meteorite delivery and more—could produce phosphine in anywhere near the part-per-billion quantities inferred from our data. In addition, there simply is not enough hydrogen nor the right temperatures and pressures for phosphine (PH3) to form on its own. We are left with the possibility of unknown chemistry, or more speculatively, the possibility of life. On Earth, phosphine gas is associated only with life, produced by bacteria in oxygen-free environments such as wetlands and by humans for industry.
What followed our announcement was healthy, but unexpectedly harsh, skepticism from the scientific community. Some reanalyzed our data and did not find the signal. Others re-found the signal but attributed it to sulfur dioxide and not phosphine. Another team found independent evidence for phosphine in archived data taken directly in the Venus atmosphere by the 1978 NASA Pioneer Venus probe. Many scientists insisted the presence of phosphine can be explained by known chemistry, though no claims have yet been substantiated with scientific publications. The debate about phosphine gas on Venus will continue.
My exoplanet “finish line” has suddenly moved from a few years away to infinitely distanced. For even if we find a potential biosignature gas in an exoplanet atmosphere with Webb (or another of the planned or proposed next-generation telescopes), will the community agree that a tiny signal is more than noise in the data? If a robust signal is found, is there any way to associate the gas with life and not from chemistry in an unknown planetary environment? After all, we will have vastly less information for distant exoplanets as compared to up-close Venus, a planet with decades of observations and visits by over two dozen spacecraft.
Thankfully scientists have no shortage of imagination. Starshot is a project to launch thousands of tiny spacechips with four-meter-wide solar sails, accelerated to 20 percent the speed of light by a bank of coherent ground-based lasers with a combined power of gigawatts. After a 20-year journey to our nearest star system, Alpha Centauri, some of the surviving and still rapidly traveling starchips will take and send images of any planets back to Earth. An equally ambitious concept envisions a spacecraft 50 billion miles away from Earth, perfectly lined up with the sun and a distant exoplanet. The telescope can then use the sun as a powerful gravitational lens to magnify the exoplanet so highly that the planet surface could be imaged at a resolution of 10 kilometers.
The discovery and characterization of exoplanets has come a long way in the millennia since humans have pondered the mysteries of the multitude of stars. We are lucky to be the first generation who will not just hope, but can truly explore the nearest stars for worlds that are habitable, and just maybe, inhabited.
MIT Professor Sara Seager’s research has introduced many foundational ideas to the field of exoplanets and is now focusesd on the search for the first Earth-like exoplanets and signs of life on them.