Recently at UT, author Matt Williams has been writing a series called “Beyond Fermi’s Paradox”, which takes a look at possible resolutions to one of the most famous questions in science: “Where is everybody?” As Matt discusses, there are multiple hypothetical solutions, but there may eventually come a day when we can definitively answer it.
Consideration of that day opens up a whole host of new questions, not the least of which is what will an intelligent civilization we find be like? Carl Sagan popularized the notion that it is very unlikely that any extraterrestrial civilization would be equivalent to ours in terms of technological progress. What he did not address was the relative age of the civilization and what that might mean in terms of their interest in communicating with us. Now a team of astronomers have come up with an answer to that question using one of the most underappreciated mathematical tools: statistics. Their model provides a simple answer: any intelligent civilization is likely older than us, and potentially much older.
We have discovered more than 4,000 planets orbiting distant stars. They are a diverse group, from hot Jupiters that orbit red dwarf stars in a few days to rocky Earth-like worlds that orbit Sun-like stars. With spacecraft such as Gaia and TESS, that number will rise quickly, perhaps someday leading to the discovery of a world where intelligent life might thrive. But if we can discover alien worlds, life on other planets could find us. Not every nearby star would have a good view of our world, but some of them would. New work in the Monthly Notices of the Royal Astronomical Society tries to determine which ones.
In the past five years, the project has made two major data releases (in the June of 2019 and February of 2020) and announced that it found no signs of alien transmissions from the 1,327 nearest star systems. But thanks to an analytical breakthrough recently proposed by researchers from the University of Manchester, it looks as though Breakthrough Listen’s search efforts could be expanded by a factor of more than 200!
In recent years, the explosive nature of exoplanet discovery (over 4,164 confirmed so far!) has led to renewed interest in the timeless question: “are we alone in the Universe?” Or, as famed Italian physicist Enrico Fermi put it, “Where is everybody?” With so many planets to choose from and the rate at which our instruments and methods are improving, the search for life beyond Earth is really kicking into high gear.
At the same time, these discoveries have inspired a plethora of new studies regarding the ongoing Search for Extraterrestrial Intelligence (SETI). This includes the Alien Civilization Calculator, which is the brainchild of physicists Steven Woodling and Dominick Czernia. Inspired by recent attempts to address the statistical likelihood of advanced life in our galaxy, they offer a mathematical tool that can crunch the numbers for you!
The extremely energetic events that we see out there in the Universe are usually caused by cataclysmic astrophysical events and activities of one sort or another. But what about Fast Radio Bursts? A pair of astrophysicists at Harvard say that the seldom seen phenomena could, maybe, possibly, be evidence of an advanced alien technology.
Fast radio bursts (FRBs) are short-lived radio pulses that last only a few milliseconds. It’s been assumed that they have some astrophysical cause. Fewer than 2 dozen of them have been detected since their discovery in 2007. They’re detected by our huge radio telescopes like the Arecibo Observatory in Puerto Rico, and the Parkes Observatory in Australia. They’re extremely energetic, and their source is a great distance from us.
The two astrophysicists, Avi Loeb at the Harvard-Smithsonian Center for Astrophysics, and Manasvi Lingam at Harvard University, decided to investigate the possibility that FRBs have an alien technological origin.
“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence. An artificial origin is worth contemplating and checking.” – Avi Loeb, Harvard-Smithsonian Center for Astrophysics
I’ll Take ‘Alien Signals’ For $200 Alex
Loeb and Lingam began by calculating how much energy would be needed to send a signal that strong across such an enormous distance. They found that doing so with solar energy requires a solar array with an area twice the surface area of Earth. That would be enough energy, if the alien civilization was as close as we are to a star similar to our Sun.
Obviously, such a massive construction project is well beyond us. But however unlikely it sounds, it can’t be ruled out.
The pair also asked themselves questions about the viability of such a project. Would the heat and energy involved in such a solar array melt the structure itself? Their answer is that water-cooling would be sufficient to keep an array like this operating.
Their next question was, “Why build something like this in the first place?”
I’ll Take ‘Alien Spacecraft Propulsion Systems’ For $400 Alex”
The thinking behind their idea is based on an idea that we ourselves have had: Could we power a spacecraft by pushing on it with lasers? Or Microwaves? If we’ve thought of it, why wouldn’t other existing civilizations? If another civilization were doing it, what would the technology look like?
Their investigation shows that the engineering they’re talking about could power a spacecraft with a payload of a million tons. That would be about 20 times bigger than our largest cruise ship. According to Lingam, “That’s big enough to carry living passengers across interstellar or even intergalactic distances.”
If FRBs are indeed the result of an alien propulsion system, here’s how it would work: Earth is rotating and orbiting, which means the alien star and galaxy are moving relative to us. That’s why we would only see a brief flash. The beam sweeps across the sky and only hits us for a moment. The repeated appearance of the FRB could be a clue to its alien, technological origin.
The authors of the study outlining this thinking know that it’s speculative. But it’s their job to speculate within scientific constraints, which they have done. As they say in the conclusion of their paper, “Although the possibility that FRBs are produced by extragalactic civilizations is more speculative than an astrophysical origin, quantifying the requirements necessary for an artificial origin serves, at the very least, the important purpose of enabling astronomers to rule it out with future data.”
There are other interpretations when it comes to FRBs, of course. The others of another paper say that for at least one group of FRBs, known as FRB 121102, the source is likely astrophysical. According to them, FRBs likely come from “a young, highly magnetized, extragalactic neutron star.”
Lurking behind these papers are some intriguing questions that are also fun to ponder.
If the system required a solar array twice the size of Earth, where would the materials come from? If the system required water-cooling to avoid melting, where would all the water come from? It’s impossible to know, or to even begin speculating. But a civilization able to do something like this would have to be master engineers and resource exploiters. That goes without saying.
Why they might do it is another question. Probably the same reasons we would: curiosity and exploration, or maybe to escape a dying world.
Greeting cards in space… We’ve certainly sent our share of them, haven’t we? So if humankind is foresighted enough to leave messages of our whereabouts – and our personalities – in space, then why haven’t other alien civilizations done the same? That’s a question a pair of postdoctoral researchers at Penn State are asking. By using mathematical equations, they’re showing us we simply haven’t looked in enough places… and would we recognize an alien artifact even if it were staring us in the face?
“The vastness of space, combined with our limited searches to date, implies that any remote unpiloted exploratory probes of extraterrestrial origin would likely remain unnoticed,” report Jacob Haqq-Misra, Rock Ethics Institute, and Ravi Kumar Kopparapu, Earth and Environmental Systems Institute, in a paper accepted by Acta Astronautica and posted online on ArXiv.
So far, we simply haven’t found any evidence of alien artifacts in our solar system – or anywhere else for that matter. According to the Penn State article, the Fermi paradox, originally formulated by Enrico Fermi, asks, if intelligent life is common, why have no technological civilizations been observed. Well, shucks… Maybe they’re shy – and maybe they’ve self-annihilated. There are hundreds of reasons “why” we haven’t found anything, but the most pertinent answer is we simply aren’t looking for the right thing in the right place at the right time. For example, have a look at just a few of the things we humans have sent into vastness of space to act as our ambassadors…
And this is only just the tip of the human iceberg. How many of us have sent our name on missions to Mars, Pluto and more? There are footprints, plaques, flags, golf balls and an endless parade of human artifacts scattered far and wide. We might think they’re in plain sight, but would an alien culture see that? Would we comprehend what an alien culture might consider to be a greeting or sign or their presence? As far as we know, there could be unpiloted probes from alien civilizations out there right now, checking us out… But unless it were something the size of a proverbial school bus dropping itself on a house in Essex, our own arrogance would probably keep us from noticing it. And then again… it just might be hidden.
“Extraterrestrial artifacts may exist in the Solar System without our knowledge simply because we have not yet searched sufficiently,” said Haqq-Misra and Kopparapu. “Few if any of the attempts would be capable of detecting a 1 to 10 meter (3 to 33 foot) probe.”
Haqq-Misra and Kopparapu use a probabilistic method to determine the feasibility of aliens leaving us clues to their existence. Their work points to the Solar System as a fixed volume and then calculates the percentages of that volume that would need to be thoroughly searched to detect an alien probe or artifact. These searches would have to involve technology able to detect small, foreign objects and then apply it to a smaller portion of the volume to look for results. It’s a study which hasn’t been undertaken so far. We simply cannot say we’ve looked everywhere…
“The surface of the Earth is one of the few places in the Solar System that has been almost completely examined at a spatial resolution of less than 3 feet,” said Haqq-Misra and Kopparapu.
Sure. There are still a lot of nooks and crannies on Earth that haven’t been thoroughly explored – and our oceans are a good example. However, when it comes to searching elsewhere, it’s been a hit-or-miss proposition. While mapping the surface of the Moon, the Lunar Reconnaissance Orbiter is looking at the surface at a resolution of about 20 inches. It may take a few years, but perhaps something isn’t buried under the regolith. As for Mars, chances are slight – but new things seem to be discovered on Mars each day, don’t they? How about the LaGrange points, or the asteroid belt? Things could be hiding there, too.
“Searches to date of the Solar System are sufficiently incomplete that we cannot rule out the possibility that non terrestrial artifacts are present and may even be observing us,” said Haqq-Misra and Kopparapu. They add that “the completeness of our search for non terrestrial objects will inevitably increase as we continue to explore the Moon, Mars and other nearby regions of space.”
After all, what did we expect? E.T. to interrupt a prime time television program to announce their presence? A take-over of the Internet? Maybe each time a meteor makes it to Earth it’s a little calling card that life-possible organisms exists outside our own little sphere…
SETI, the Search for Extraterrestrial Intelligence suffered a big blow in April of this year when the primary alien search engine –the Allen Telescope Array (ATA) in northern California — was put into “hibernation” due to lack of funds. But now you can help get the ATA back online through a crowdsourcing effort called SETIstars. Similar to fundraising efforts like KickStarter, SETIstars is working to raise enough money to bring the telescope array online again and provide operating costs for at least one year. The goal is to raise $200,000.
As of this writing, nearly $30,000 has been raised already.
While the ATA is not the only radio telescope that can be used for SETI searches, it was the observatory that was primarily used for that task. The funding crisis occured when state and the National Science Foundation contributions were significantly cut.
SETIstars is an initiative by the SETI Institute to rally support from the community to help fund the SETI Institute’s operations and that of the Allen Telescope Array. SETIstars has clearly defined fundraising goals, and will recognize supporters and contributors to the SETI Institute — both financial and non-financial.
“We are starting with a simple site with a clear mandate: raise funds from the community to help bring the ATA back on line,” says the SETIstars website. “But this is just the beginning…Bringing the ATA back online is a critical first step. However, sustaining operations is also of vital importance. SETIstars will be a rallying point for future community engagement and fundraising efforts.”
Here’s your chance to allow SETI scientists to start listening for signals from space again, especially in the region in space where Kepler has found a boatload of exoplanets. Your donations are tax free (in the US) since SETI is a nonprofit institution. International donors should contact their government for information on tax deductions for charitable gifts to U.S. based charities.
Recently, some researchers speculated on what types of observational data from distant planetary systems might indicate the presence of an alien civilization, determined that asteroid mining was likely to be worth looking for – but ended up concluding that most of the effects of such activity would be difficult to distinguish from natural phenomena.
And in any case, aren’t we just anthropomorphizing by assuming that intelligent alien activity will be anything like human activity?
Currently – apart from a radio, or other wavelength, transmission carrying artificial and presumably intelligent content – it’s thought that indicators of the presence of an alien civilization might include:
• Atmospheric pollutants, like chlorofluorocarbons – which, unlike methane or molecular oxygen, are clearly manufactured rather than just biogenically produced
• Propulsion signatures – remember how the Vulcans detected humanity in First Contact (or at least they decided we were worth visiting after all, despite all the I Love Lucy re-runs)
• Stellar engineering – where a star’s lifetime is artificially extended to maintain the habitable zone of its planetary system
• Dyson spheres – or at least their more plausible off-shoots, such as Dyson swarms.
And perhaps add to this list – asteroid mining, which would potentially create a lot of dust and debris around a star on a scale that might be detectable from Earth.
There is a lot of current interest in debris disks around other stars, which are detectable when they are heated up by the star they surround and then radiate that heat in the infra-red and sub-millimeter wavelengths. For mainstream science, debris disk observations may offer another way to detect exoplanets, which might produce clumping patterns in the dust through gravitational resonance. Indeed it may turn out that the presence of a debris disk strongly correlates with the existence of rocky terrestrial planets in that system.
But now going off the mainstream… presuming that we can eventually build up a representative database of debris disk characteristics, including their density, granularity and chemistry derived from photometric and spectroscopic analysis, it might become possible to identify anomalous debris disks that could indicate alien mining activities.
For example, we might see a significant deficiency in a characteristic element (say, iron or platinum) because the aliens had extracted these elements – or we might see an unusually fine granularity in the disk because the aliens had ground everything down to fine particles before extracting what they wanted.
But surely it’s equally plausible to propose that if the aliens are technologically advanced enough to undertake asteroid mining, they would also do it with efficient techniques that would not leave any debris behind.
The gravity of Earth makes it easy enough to just blow up big chunks of rock to get at what you want since all the debris just falls back to the ground and you can sort through it later for secondary extraction.
Following this approach with an asteroid would produce a floating debris field that might represent a risk to spacecraft, as well as leaving you without any secondary extraction opportunities. Better to mine under a protective canopy or just send in some self-replicating nanobots, which can separate out an enriched chunk of the desired material and leave the remainder intact.
If you’re going to play the alien card, you might as well go all in.
Fifty years of eerie silence in the search for extra-terrestrial intelligence has prompted some rethinking about what we should be looking for.
After all, it’s unlikely that many civilizations would invest a lot of time and resources into broadcasting a Yoo-hoo, over here signal, so maybe we have to look for incidental signs of alien activity – anything from atmospheric pollution on an exoplanet to signs of stellar engineering undertaken by an alien civilization working to keep their aging star from turning into a red giant.
We know a spectroscopic analysis of Earth’s atmosphere will indicate free molecular oxygen – a tell tale sign of life. The presence of chlorofluorocarbons would also be highly suggestive of advanced industrial activity. We also know that atomic bomb tests in the fifties produced perturbations to the Van Allen belts that probably persisted for weeks after each blast.
These are planet level signs of a civilization still below the level of a Kardashev Type 1 civilization. We are at level 0.73 apparently. A civilization that has reached the Type 1 level is capable of harnessing all the power available upon a single planet – and might be one that inadvertently signals its presence after thoughtfully disposing of large quantities of nuclear waste in its star. To find them, we should be scanning A and F type stars for spectral signatures of technetium – or perhaps an overabundance of praseodymium and neodymium.
We might also look for signs of stellar engineering indicative of a civilization approaching the Kardashev Type 2 level, which is a civilization able to harness all the power of a star. Here, we might find an alien civilization in the process of star lifting, where an artificial equatorial ring of electric current creates a magnetic field sufficient to both increase and deflect all the star’s stellar wind into two narrow polar jets.
These jets could be used for power generation, but might also represent a way to prolong the life of an aging star. Indeed, this may become a vital strategy for us to prolong the solar system’s habitable zone at Earth’s orbit. In less than a billion years, Earth’s oceans are expected to evaporate due to the Sun’s steadily increasing luminosity, but some carefully managed star lifting to modify the Sun’s mass could extend this time limit significantly.
It’s also likely that Type 2 civilizations will play with Hertzsprung–Russell (H-R) parameters to keep their Sun from evolving onto the red giant branch of the H-R diagram – or otherwise from going supernova. Some well placed and appropriately shielded nuclear bombs might be sufficient to stir up stellar material that would delay a star’s shift to core helium fusion – or otherwise to core collapse.
It’s been hypothesized that mysterious giant blue straggler stars, which have not gone supernova like most stars of their type would, may have been tinkered with in this manner (some stress on the word hypothesized there).
As for detecting Type 3 civilizations… tricky. It’s speculated that they might build Dyson nets around supermassive black holes to harvest energy at a galactic level. But indications are that they then just use all that energy to go around annoying the starship captains of Type I civilizations. So, maybe we need to draw a line about who exactly we want to find out there.