My personal thoughts about the field of astrobiology is that it should study the only life that we know of in the universe - that is, the biosphere of the Earth - and do so from an astronomical perspective. That is, it should study Earth as a place in the universe and try to explain why this particular place is so habitable.
This, of course, implies trying to hunt down the actual emergence of life on the Earth. How did it happen? Why did it happen?
Chris wrote:
There is very good work being done in this area, and no reason to even think there is a well defined distinction between living and non-living.
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But people have very interesting ideas- ideas that are consistent with our understanding of the early Earth environment and with our understanding of chemistry and biology. (There is a report out just today about the role of clay in the creation of life.) From a scientific standpoint, we're probably back in the realm of complex systems, meaning that no simple theory may exist to describe how life formed on Earth. Instead, we probably have a complex interaction of chemical and geophysical systems, along with an evolutionary process (evolution even before something reached the stage that we'd unambiguously call "alive"). And this over millions of years, perhaps. So it may not be testable in a lab at all, except in pieces, subsequently modeled by simulations. A complicated bit of science, to be sure.
I have been thinking about this - the idea that life formed gradually from non-life over many transitional forms and millions of years, and I find the suggestion absolutely compelling. It appeals to my amateur sense of scientific beauty, that much is certain.
But if that is how it happened, does that in itself prove that the same slow non-life-to-life process is likely to happen elsewhere? It happened once, yes. Does that mean it is bound to, or likely to, happen over and over again wherever there is a suitable planet in a habitable zone?
My objection to astrobiology is that I think that the emergence of life from non-life is not sufficiently well understood to use it as a starting point to draw conclusions from. I don't mean to criticize those who try to understand how life came about. Absolutely not! Clearly this of field of research is totally fascinating! I'm just saying that until we have a firmer understanding of how the life-creating processes work, it is just too hard to predict how often they will happen elsewhere. And that is why I think that astrobiology should really concentrate on life on Earth, because I don't think that astrobiologists necessarily know what they are talking about when they make assumptions about the nature and prevalence of life elsewhere.
Unlike Rob, I have no objection whatsoever to the study of gravity waves. No one has seen gravity waves yet, but we have a firm theory explaining why they should exist. I'd like to compare gravity waves with the Higgs particle, because for the longest time no one had seen the Higgs particle either, but particle physicists had a firm theory explaining why it should exist. All they needed to do to make Higgs come out of hiding was to build a gigantic particle accelerator, run the accelerator to its limit and work their own little backsides off in a totally heroic effort to spot the tracks of the stubborn little bugger as it exploded in a blast of particle glory. Finding the Higgs particle was hard, hard work, but the scientists knew why it should exist and how they should find it, and finally, finally they succeeded. The gravity waves people haven't succeeded yet, but who is to say that they won't do so in the future?
But I don't think astrobiologists have presented a firm theory explaining why there should necessarily be life on other planets. I don't think they have managed to make life on other planets a necessary part of any sort of standard theory explaining the universe. Let me put it like this: the Higgs particle had
better exist, or so many assumptions about the universe we live in would have been proved wrong. Gravity waves had probably better exist too, because if they don't then there is something fundamental that we don't understand about the crucial role of gravity in the universe. But suppose we don't find any life away from Earth in the foreseeable future. What part of our understanding of the universe breaks down if we fail to find life away from Earth?
So in other words, I don't think we need to find life in space in order to make any sort of grand unified theory work. Life in other solar systems is
optional to our understanding of the universe. It might be there or not, it might be rare or it might be there all over the galaxy. What exactly can we conclude about the laws of physics if life is rare, and what can we conclude about these laws if life is common?
This is my point. Astrobiologists are not working from a firm, rigorous theory explaining why the "exo-life" they look for is a necessary part of the universe. And not only do they lack a firm theory, but they lack any real observational evidence, too. The way I see it, they are floundering. Wasn't it Einstein who said something to the effect that anyone who has a fixed point to start from can dislocate the universe?
At least the gravity waves people have a beautifully firm theory to start from. Who knows if they can't dislocate the universe enough to find the waves that
must be there?
Ann