So essentially the number one question everyone has on their mind when they meet an astronomer, and the first question I normally get asked is:
ARE THEY OUT THERE?
Related to this topic, Prof. Sara Seager gave a talk on exoplanets at Stanford in May of 2018.
She is an expert in this area, and gave a fantastic talk. I have my own feelings on the issue, that you can see if you follow the email exchange below I had with Sara in 2013.
No one has yet taken me up on the bet I mention below -- might *you* be willing to step up, to it? :->
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Here's the email exchange i had with Sara in 2013:
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Date: Thu, 10 Oct 2013
hi Sara- just heard your interview on a TTBOOK podcast ( http://archive.ttbook.org/book/sara-seager-exoplanets-0 ) , and though i liked your energy and enthusiasm, i was a *bit* surprised at one of your comments, and that was that there is a *100%* chance of there being life on another planet.
I was floored by this.
Now -- i'm a cosmologist (doing gravitational lensing), and not in exoplanet work at all, but just before this comment in the interview, you'd admitted that you are an astronomer, not a biologist, and don't know the likelihood of life evolving etc. And then you said "100%"!
Here's the thing -- yes, i believe life is *likely* -- but i also believe we have *ZERO* idea about the true value of several of the 7 factors in the Drake equation [that gives the chance of intelligent life contacting us]. We now only in recent years have a good idea of the astro ones -- how many planets orbit in the habitable zone and such -- but we don't know if the probability of life evolving on any given planet is just small -- or *really* small.
Yes, there are something like ~5e11 stars (or more), and 1e11 galaxies in the observable Universe. So that's 5e22 planets.
What if the chance of life evolving (along with it evolving enough to produce O2 or methane, since we don't need to hear radio signals to see those) is about 2e-23 -- so the total expected number is unity, and we got lucky and happen to be the only ones?
What if?
You may say it's unlikely -- but have you much more to back that up than belief, at some level?
If so, i'm happy to hear it, because *i* certainly don't know how we'd get to this number!
(And yes, i know we can make amino acids and whatnot by irradiating a primordial-type mixture with ultraviolet light and such -- that's still far from life. Perhaps *really* far.)
Look -- i would *love* to find evidence of other life within my life *as much* as you or anyone else in the general public (who really care about this, as you rightly point out). I have just long wondered about the Fermi Paradox, and am perhaps less optimistic than many of the Planet Hunters about this (i was a postdoc at Ohio State, and know several of the forefront planet-hunters active in this, so i've definitely been exposed to some of it).
Ok -- thx in advance for any thoughts or info you might be willing to pass on, about this.
cheers--
-Mandeep G.
ps. Another thought i had: apart from info you could pass on to me, i'll tell you what -- even though i'm not sure, and don't have *such* a strong feeling about it, i would be so happy to *lose* a public bet with you on this that i would offer you a $1000 wager (with the money going to an environmental cause of your choice, maybe..?) on something like LongBets in the public arena that we will *not* find incontrovertible evidence of life-producing gases on another planet within what, 15 yrs? Whatever kind of terms you think would seem fair. I would really be happy to take you up on this if you might be willing, and haven't already done so (?)
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Date: Fri, 11 Oct 2013
From: Sara Seager
Whatever I actually said was (*is always*) preceded by "my personal opinion" or "I can only speculate" or some such. If they cut out that important caveat then I'll have to change how I say it in the future, so thanks for the heads up.
Sara Seager
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Date: Fri, 11 Oct 2013
From: Mandeep S. S. Gill
hi Sara-
Ok, great, thx much for writing back, appreciate that -- you don't mention the bet idea, so i'm guessing you're not up for that.. though i wish you would be! :-)
I'll start asking around with my exoplanet-hunter friends, see if i could get someone to take it up -- i think it would be a neat thing to be out there in the public to make us all even more excited about future possibilities in finding life Out There.
cheers--
M
