Is There Anybody Out There?

Why are we here? Why did life evolve? Why did it evolve on Earth - and how? How did humans come to dominate? And - are we alone in the universe?

Age old questions. Some of which we more or less know the answers too and some of which we are still arguing about. But it's the final one, are we alone? - or - is there anybody out there? - that we still don't know the answer too and it was that question that was being addressed at last night's Skeptics in the Pub - Online talk, Where alien worlds are born:exoplanets and their formation environments, with Dr Cass Hall, an assistant professor of computational astrophysics at the university of Georgia in the US.

As you might be able to guess from her job description, there was not a lot of talk of little green men, The X-Files, Star Trek, or Star Wars. That, for some perhaps, made it a little dry. For me, the heavy level of science made the talk, fascinating though it was, in places, quite difficult to follow. It was almost a relief during the Q&A when somebody asked Dr Hall what her favourite chocolate bar was:- Mars, Galaxy, or Milky Way?

Galaxy, apparently. Dr Hall didn't linger long on confectionery and, with some massively complicated equations occasionally filling the screen - on a subject I already could barely understand, her talk began in Chile's Atacama desert with the sixty-six enormous radio telescopes that are looking out into the great beyond in an attempt, among other things, to find alien worlds. To look for planets like our own that can host life.

These ALMA telescopes have revealed solar systems and a distant spiral galaxy (a collection of solar systems) not too different to the one we live in forming now. This galaxy, like our own, consists of hundreds of billions of stars, like our very own sun. Each of these stars has at least one planet orbiting it. Taking into account the sheer number of solar systems it is estimated that there are 100,000,000,000,000,000,000,000 (or ten to the power of twenty-three) planets in the universe. And growing.

That's a lot of planets for even the giants of the Atacama to be looking at so if we can find solar systems like our own, but four billion years younger and still forming, then that may help us find out how the Earth formed, how life on Earth formed, and what planets may have the conditions on them that would enable what appears to be some kind of one off miracle to happen again.

What we're really looking for is what's called an 'exoplanet'. That's a planet in orbit around a star that is not our sun. A lot of science-fiction, especially retro sci-fi, is about aliens coming from Saturn, Venus, and, especially, Mars but it seems likely that if there was life on these planets we'd have been in contact by now. We've tried hard enough.

So, how do we find these distant exoplanets when they are so feint compared to the much larger stars they orbit? There are three methods. The 'transit' method involves watching a planet pass in front of its star and measuring its drop in brightness, 'radial velocity' measures how much the planet makes the star 'wobble' on its access when it's close to it - gravitational pull of sorts, and 'direct detection', which I'm sure Dr Hall explained very well, is such a complicated and confusing method I simply couldn't understand it.

These blogs, remember, are not science lessons but one man's account of his life and his attempts to learn during that life and become a better person by doing so. It's been an ongoing process writing these (this is the 846th one) but it is nothing compared to Dr Hall's research. She has plotted a map, of sorts, of all known exoplanets and lots of them are in clusters that look very different to the formation of our own solar system.

Planets can be very different. There can be gas giants, ice giants, cold gas giants, hot Jupiters, rocky planets, ocean worlds, and lava worlds and to understand this diversity we need to know what caused individual planets to be formed in such ways. That's not easy as planets are normally formed in a cloud of gas and dust.

Being light years away too, it's hard to observe closely. But it's getting easier. Recent technological breakthroughs have shown enormous accretion disks forming in the sky that slowly, sometimes over ten million years, break down to form planets. Humans have not been around long enough, of course, to observe a full planetary formation.

Because of this there are huge gaps, so far, in the knowledge of even experts like Dr Hall. We need more formation models to understand all the data we are collecting and we can't begin to understand why Earth appears to be so special, so unique, until we really know what happens when planets are formed.

It was quite a frustrating way for the talk to end (not that I think anyone was expecting this to be the forum in which definitive proof of alien existence was confirmed) but as a Skeptical event it was more about the search for truth than the search for aliens. Unusually, for a Skeptical event, alien life could not be debunked completely, absence of evidence is not evidence of absence, but Dr Hall thought the likelihood of extra-terrestrial existence, though desirable to her, to be unlikely.

She gave lots of reason why she believes we are (probably) alone (though many, even in her community, disagree with her) and though I was inclined to agree with her (even though I'd like to meet a cool alien and have one as a friend) when the video link broke down during the Q&A one wag remarked that this must surely be proof of angry aliens mischievously proving their existence to doubters. As I drifted off to sleep later that night I swear I had visions of Mork in a spaceship very much like the one Mr Spoon captained in Button Moon flying off through the inky darkness to the distant planet of Kepler-13Ab.

Thanks to Dr Cass Hall, and to Andrew Taylor of the Manchester branch of Skeptics, for another illuminating, informative, and other-worldly evening.