|Just like Earth! [in an artist's ebullient imagination] Credit:|
NASA Ames/SETI Institute/JPL-CalTec:
A planetary plenitude
This discovery is called by the ever-sober news media an 'earth twin' or as the knowledgeable NY Times puts it, 'perhaps a cousin' (whatever that means). Sssh! If you keep very quiet, you might be able to hear your Keplerian kin-folk talking!
Well, we can overlook such verbiage since ours attempts to be a science blog.
Actually, the discovery of a plenitude of possible planets, or 'habitable' ones as they seem often to be referred to, is interesting and continues apace. They now number in the hundreds and only a trivial fraction of the universe has been scanned, or is even scannable with available technologies.
These truly are interesting findings, though they are, surprisingly, not at all surprising. After all, space is massively large and filled with a chaos of objects hot and cold, large and small. If, as seems likely, Newton was right and gravitation is universal, then the small stuff will often be captured by the gravitational attraction of the big stuff. Big hot stuff (stars) can capture smaller wandering rocks and they'll end up in orbit. Some even smaller rocks are captured by the pull of, and orbit around, bigger rocks (like moons around planets). Lots of other rocks and stars will be in all sorts of relationships as well. But some of these will be special.
If we care about our sort of life, then we want what is being called a Goldilocks planet: like her porridge, the rock will be not too hot, and not too cold, not too wet and not too dry, but just right! That is, there will be water and warmth enough to keep it liquid but not turn it all to steam, and other things of that sort. There is where, we're told, we'll find the ETs. Some day.
Now this is genuinely thought-provoking, but it needs none of the circus hype of the news media. That's because it basically tells us what we already knew. In fact, the actual facts are to us a lot more interesting than the Disneyfication.
We've previously in general terms discussed the idea that if there are an infinity of starts, galaxies, planets or universes, there would just as likely be all sorts of life on them. Here, we can be a tad more specific than that. For example, if there are hundreds of planet-like things just here in our own local galaxy (the Milky Way), somewhat like 186f, and we've really just begun looking and technically can only see some of what might be out there, and if what we know is largely within our own galaxy, where there are in the range of 100 billion stars, then thousands and thousands of those stars must have orbiting rocks. There are around 100 billion other galaxies (give or take a few), and we can assume that there must be thousands upon thousands of the same sorts of rocks orbiting stars and rocks orbiting around those rocks, in each galaxy.
That is, even on the back of the proverbial envelope, one would estimate that there would be at least 100 thousand billion habitable planets. That is 100 trillion planets (100,000,000,000,000), as a minimal estimate. Once we knew that there were 'habitable' rocks orbiting stars, such as Earth and perhaps one or two more even just around our own sun, there likely are around 100 or more billion earth-maybes in the Milky Way alone! Of course, if you hold to Genesis, our Earth could be God's only watering hole, but once we had clear evidence of other possibles, a reasoning person must accept that these larger numbers become plausible.
The point is that even without the Kepler and other telescopes scanning the heavens for these things, the totally convincing plausibility argument would be that the universe is awash in 'habitable' planets.
Now the fact that there are lots of warm, wet rocks out there is one thing, but it doesn't imply that there is anybody living on them. However, life--even just our sort of life--is clearly possible because we're here living it as proof. Given that, even a modest kind of belief in natural science would lead one to believe that if you have 100 trillion tries, there really has to be some sort of life out there, and probably lots of it, even if it's only on a trivially teeny fraction of the habitable planets.
This of course does not address whether it's our sort of life in the 'intelligent' sense. Or life based on DNA. The fact that we are here is not quite so persuasive about that, because the numbers get astronomical (so to speak, but in the other direction--of smallness). The number of nucleotides in earth-life's genetic history, from primal RNA to global DNA today, likely dwarfs even 100 trillion. Each has arisen and/or later been changed by largely independent individual probabilities that are very, very small. A net result is, in essence, the product of these probabilities (this and this and this...and this--the result--had to happen). So to go from primal soup to any given form of complex 'intelligence' over 3.5 billion years, that is, our form of it, would be minuscule relative even to the numbers of potentially habitable planets. This could mean that intelligent life arising more than once, even with so many trials, would be very unlikely, and thus that we are lonely in our uniqueness.
But if others just like us may not happen more than once, there are also countlessly many such pathways to intelligence: after all, each human has a different genotype and there have been billions upon billions of us. So it really is impossible to do more than muse about what the net resulting probabilities are. To a great extent it depends on what we count as intelligent life. To a greater extent, "Are we alone?" is hardly even a scientific question to ask.
Worse for NASA (and Disney) is that even here on Earth where we know intelligent life has arisen, we've only been at it for, say 1,000,000 years, being generous and depending on what 'intelligent' means. But if it means having language and communicating by electromagnetic radiation (like radio), so we could communicate with ET's, that's only been about 100 years and probably we won't last much longer, either. So the probability that at any given time smart life is present in us and any other such place is a minuscule fraction of the time that life has been around on any of these lucky 100 trillion planets.
In that sense, large numbers don't nearly guarantee that there are smart anythings anywhere else. The chance that us-like life is out there now, and that 'now' means we can communicate with it, becomes possibly rather miniscule.
Forget about chatting!
In one of our previous posts about Gliese 667C, we note the problems about thinking that we could communicate with, much less actually go to, such places (assuming we understand physics, like the limiting speed of light, correctly).
Kepler 186f is said to be about 500 light years away. That means that a signal that we can pick up from there was sent when Da Vinci was painting the Mona Lisa. If there was intelligent life there, and they're at all like us, they may well have obliterated themselves long ago. But suppose they're peaceful (having evolved way beyond us), then just to send a friendly radio wave of "Hi!" to them, and get a wave back would take until the year 3014. By then most everything would have changed about human life here, with lots of world wars (though, of course, Republicans would still be trying to keep ordinary people from being able to afford a doctor). Forget about chatting with the ETs! Even Google will be out of business by that time.
And as we said about Gliese 667C which is a mere 22 light years away, 20 times closer than 186f, physically getting there would not be half or any of the fun. It would be impossible in any practical sense, and even if we could actually do it, it would take millennia of space travel to get to 186f, and when we got there there might be nobody still around to drop in on.
So, what is the purpose of the space probe?
Without being too much of a spoil sport, because up to a point this kind of exploration really is interesting and in some ways now and then may tell us important things about our universe (not likely to be comforting to dogmatic religion), we have to ask about the purpose of this kind of probing. In a sense, for reasons we suggest above, the numbers suggest that it really tells us nothing that we didn't have almost just as strong a reason to know anyway. It would take something like a Genesis literalist to think that there would be no other planets with life on them, or even that they would be very few. And of course either we think these findings suggest the plausibility that forms of life must exist out there, or else the burden of proof should be on a denier to show how, in the face of these overwhelming numbers (and not counting theories about multiple independent universes), there could fail to be some such 'life' on lots and lots of planets.
Of course, this is really just science fiction, almost literally. The vast majority of any such planets are, were, or will be millions or even billions of light-years away. That means what we see today isn't there now, but was there eons ago. Much of that light has been streaming here since before there was life on Earth--or even before there was an Earth! Indeed, if a typical star's lifetime is around 10 billion years, much of what we see no loner exists as such and, likewise, much or most of what actually is out there came into existence too recently (even if millions or billions of years ago) for any evidence to have reached us.
So, it takes either a television sci-fi producer, a NASA PR rep, or a real dreamer to think we could ever go there or really communicate with much or even any of what must be out there. If we really thought anything like that, we should intensely be doing very down-to-earth studies to see if the speed of light and relativity are limiting factors or whether transformative new aspects of space itself remain to be discovered.
At what point is the research cost** not worth the number of people who could be fed by the same funds, and so on? When does asking such questions make one just a killjoy, and when does it make one concerned for the problems, and the actual unknowns, on the one planet we actually can do something about?
**Or, as we've suggested before, if this really is mainly just entertainment, why not let the video or other entertainment industries pay for it?