Spying on Aliens

As someone who studies the origin of life, I read my fair share of extra-terrestial theories. Some such as panspermia come from scientists. Others come from science fiction writers. And yet others come from quackery and conspiracy theorists. UFO investigations pop up on a regular basis. We seem very interested to know whether we are alone in the universe – is it idle curiosity or a deep-seated aspect the human psyche? And how will we know if there is extra-terrestial life, scientifically speaking?

 

All this and more is discussed in The Little Book of Aliens. The author, Adam Frank, is a physics and astronomy professor who also has grant funding to hunt for alien technosignatures. This was a fun book to read – Frank is an irreverent and engaging writer! I learned about the history of SETI and why it was so difficult for them to get funding as the UFO-craze made their search for alien life sound like scientific quackery. Frank tackles the Fermi paradox head-on by discussing why we have not been visited by “technologically advance, star-faring civilizations” or maybe why they haven’t revealed themselves. Perhaps they are just spying on us. But it turns out we’re also spying on them. Or at least trying to do so.

 

Frank makes a big deal about standards of evidence. This is key to distinguishing between UFO quackery and doing good science. He discusses Drake’s Project Ozma that utilized the Green Bank radio telescope to find search targets within ten light years from our planet – these were Tau Ceti and Epsilon Eridani. He discusses the important interplay between theory and experiment in formulating the idea of habitable zones. (Water is important!) Dyson spheres are also discussed. (Energy is important!) And how to detect them. (Thanks to the second law of thermodynamics, even the most efficient energy collectors will heat up and “glow” in the infrared.) An idea new to me was the Kardashev Scale, which outlines the evolution of a technologically-driven civilization. (Earth is at 0.7 on the scale! We haven’t quite harvested our entire planet’s energy.) He also discusses many of those UFO and UAP sightings you might have heard about. (No, there’s no significant proof of alien encounters yet.)

 

The most interesting chapter was on how difficult interstellar travel can be. Not only does it limit our ability to explore other stars and planets, it makes it very difficult for aliens to come to us. Frank covers generation ships, cyrosleep technology, light sails, wormholes, and warp drives – all staples of science-fiction. (Some science is involved, but achieving the technology may be practically impossible.) One thing I liked about The Expanse series, is that although the ring gates provide a wormhole-like system to exploit, the reality of much of space travel is doing slow burns that take days and weeks across long distances in the expanse, even within our own solar system. The human body can only withstand so much g-force even with a cocktail of body-stabilizing chemicals. Frank also has a frank discussion about anti-gravity devices and whether one can manipulate inter-dimensional space. (It’s very hard to get around the laws of physics!)

 

Then there’s the science. What can we do now? We can spy on other worlds through our telescopes. Before the 1990s, many of the terms in the famous Drake equation were a challenge to determine. But then astronomers found the first exoplanet. And then there were more. Many more! Thirty years later, we’re much better at looking for them – and we can begin to say something about their atmospheres. This could provide a clue that life exists on an exoplanet – if aliens were spying on us, they’d figure out that our atmosphere is out of equilibrium in a way that cannot easily be explained by an abiotic mechanism. Frank argues that while water is important, so is land. And ice can be a life-killer. It was almost so when our planet endured close to Snowball Earth conditions. But an alien spyglass would also detect that the side of our planet not facing our sun is bright with artificial (electric) light. (We have technology!) We might be able to spy back and come to the same conclusion.

 

Besides looking outside our solar system, we could also search within our system for potential alien artifacts. While it may be hard for bodily wetwork organisms to survive an interstellar journey, inorganic machine probes could travel lighter and faster. Frank tackles the now-famous Oumuamua object that some astronomers had identified as a potential alien probe. There is some evidence in favor but other evidence against. But our time-frame was limited as the object has now passed by and all we have left is the limited data that was collected.

 

In the final chapter, Frank has fun speculating. Must life be carbon-based? (My answer as a chemist is very likely so. Nothing else has the versatility of organic chemistry.) If alien life exists, will it show convergent or divergent evolution? (I’d say both. There are constraints and there are degrees of freedom.) How would you talk to an ET? (I discussed this with my students on Star Wars Day!) Should we even be signaling our existence to aliens? (After reading The Dark Forest, I’d say not.) And the most important question: “Will the biological era be short?” Essentially, will machines take over? (Sci-fi has discussed this in spades.) Frank also outlines how we could think about “million-year-old civilizations”. One might consider our human civilization (with the birth of cities and agriculture) to be barely ten thousand years old. And in the last five hundred, we have completely changed the surface of our planet and are bumping up against serious climate change. Whether we can survive another five hundred years is a very interesting question. Perhaps spying on and finding an “old” alien civilization will help us weather the coming storm.