The age of our universe and the commonality of Earth-like planets indicates the possibility of alien civilizations either today or in the past. SETI — Search for Extraterrestrial Intelligence — has been actively listening to the cosmos for radio signals since the 1960's, but the advent of JWST gives astronomers the ability to observe promising stars and exoplanets within our own galaxy. One way we could detect advanced alien civilizations is by searching for the influence of technology on planetary atmospheres or their stars. A new project at Uppsala University, Sweden may give new insights into the search for signs of intelligence alien life.
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Astro Brief is a podcast collaboration between KSMU, the Missouri Space Grant, and MSU's Department of Physics, Astronomy and Materials Science. Hosted by Dr. Mike Reed, Astro Brief focuses on astronomical events, the field of astronomy, and astronomy-related guests. It airs Thursdays at 9:45 am on KSMU.
Transcript
In this episode, we're going to explore ways to find alien civilizations — not just life beyond Earth, but intelligent life that is technologically as advanced as us, or even beyond that.
Life beyond our Earth is, of course, one of the most fundamental questions to humankind. Are we alone in this vast universe? Why should or shouldn't we consider that we are the only ones?
Let's start with some numerology. Evidence indicates our solar system is less than half the age of our galaxy and about one-third the age of our universe, so we are relatively young — meaning there's no reason to expect that we should be the first to develop life. However, the early universe lacked heavier elements — the sort that make up rocky planets and the materials in our cell phones and cars. So our age in the universe is both a pro and a con for the existence of alien life.
We should also consider the huge number of other planets. An article from 2020 by Michelle Kunimoto and Jaymie Matthews of the University of British Columbia estimated there are 6 billion — with a B — planets in our galaxy that are Earth-like around stars fairly similar to our Sun. If you allow for smaller stars — which are more common — yet put a habitable planet closer in, then the estimate could rise up to even 40 billion Earth-like planets in our galaxy alone. So there's lots of potential real estate and plenty of time in the universe for alien life to develop and evolve intelligence.
Since those aliens have not landed on Earth and announced themselves, how do we go about finding them?
One of JWST's main goals is to measure atmospheres of exoplanets and if, like us, an alien civilization is affecting their atmosphere, JWST might find it. Now we have to add that JWST is pretty limited when it comes to Earth-like-sized planet atmospheres. It cannot simply point to an exo-Earth, take a picture and it's done. No, it has to get a high-resolution spectrum and that requires a lot of time. I recall hearing a talk which estimated that if JWST spent all its time looking at exo-Earth atmospheres, it could do 50 over JWST's expected lifetime. So that's pretty limited and of course the atmosphere would have to have been changed in a way that nature itself would not. And nature's pretty inventive.
To date, JWST has looked at three rocky exoplanets — two would be too hot for life anyway, with bubbling magma oceans and for the third, JWST did not detect any atmosphere. That doesn't mean one isn't there, just that JWST couldn't detect it. Another perhaps easier way to find alien civilizations is how the search for extraterrestrial intelligence or SETI has gone about it and that is to just listen. Us humans have been inadvertently sending signals out into space for over a hundred years. We've even intentionally sent out high-powered signals a few times since the 1970s. So SETI listens.
It's estimated, they've listened in the direction of over 6 million stars and there's been no convincing alien signal detected. Six million seems like a lot but our galaxy has over 400 billion stars. And of course the farther away the source of a signal, the more it gets attenuated by distance, making it harder to detect. Uppsala University in Sweden has begun a new way to search in what's called Project Project Hephaistos. Project Hephaistos is the ancient Greek god of metalworking, smiths and craftsmen which is fitting as this project is looking for Dyson spheres or other technological constructions.
A Dyson sphere is an energy collecting construct around a star.
Our sun emits far more energy than we'd ever need to power our civilization including data centers but collecting that power is difficult. One solution as proposed by physicist Freeman Dyson — not the vacuum cleaner guy — would be to construct collectors in space around the sun as belts or even complete spheres. One consequence however it would be that those collectors would also get very hot and so they would need to dissipate heat and that would happen at longer wavelengths. From the outside — assuming the Dyson sphere doesn't engulf the entire star — there would be an infrared excess and that's what Project Project Hephaistos is looking for. Using publicly available sky surveys, project scientists searched 5 million stars looking for excess energy at longer wavelengths and they found 7 good candidates. Recently JWST has observed 2 of those candidates and instead of Dyson belts or spheres it detected background galaxies which were unresolved in the previous data. So 2 stars are removed from the 7 with 5 candidates left.
Our search for technosignatures of alien civilization continues.