Information theory is a fundamental constraint on any halfway sensible theory of life. If you can't pump out entropy faster than it comes in, you will, by definition, be randomized, which pretty much by definition is not alive.
I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive. There are in fact certain very powerful and generic limits that can be placed on life with some powerful mathematics, such as the one I mentioned. It's fun to imagine a life form in science fiction that lives on the surface of the sun, but in reality they are not possible; there's no way they could retain any interesting structure in such a high entropy environment. To argue otherwise is basically to be arguing against thermodynamics. This basically puts this position firmly on the "crank" side, not the scientifically knowledgeable one.
Also, the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life. Even if we manage to find a few simple life forms in a few of the slightly less hostile places in the solar system, it still won't change that fact; life is observationally not abundant everywhere, regardless of conditions. There definitely is a difference between conditions conducive to life and those not. Even what we call "extremophiles" are only surprising in purely local terms; in absolute terms in the Solar System, volcanic vents are still incredibly hospitable places compared to what is out there. In its own way, trying to argue from extremophiles to the general case is its own perversively parochial argument; the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint.
>"If you can't pump out entropy faster than it comes in, you will, by definition, be randomized, which pretty much by definition is not alive
You're essentially just saying "if you can't stay alive, then you're dead". It's a non-statement.
My point was that's a big if. There are environments in which we wouldn't have thought it possible, until it was proven otherwise.
"I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive"
I don't think it particularly sophisticated to hold this view. I think it simply acknowledges the limitations of our knowledge (limitations which have been proven time and again). As a result, "naive" is actually the word I'd use to describe those who believe that their prior observations represent the full set of possibilities. The world was once flat and all of that.
So, ironically, I would say that your entire argument is based on a profound naivete. It is limited to what we currently understand/have observed and it assumes that it is foolish to consider otherwise.
>the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life...
What does that mean? I don't think that anyone's asserting that life must exist in every single place we look; rather simply that some form of life could exist in virtually every single place we look, because we truly do not know what the bounds are. And, at a minimum, it almost certainly exists in places that we don't expect. The more general point is that it's extraordinarily presumptive to conclude that we know definitively what life could be, based simply on our own observations to date.
>the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint.
Well, exactly. That's my point. We've dubbed them "extremophiles" because of our own limited reference point at a particular place in time. Their existence is simply evidence of our limited observational knowledge in the past. Ironically, enough, that's a term that is still generally accepted because even in spite of them showing us that we were wrong about life at some point, we still can't quite wrap our minds around the fact that we were wrong.
Now, you are simply arguing from a slightly evolved set of observational knowledge that happens to accommodate the existence of those "extremophiles". But, you're simply saying "OK, we might have been wrong once. But, we can't be wrong again". It's really an odd argument to make. And you're adding that volcanic vents aren't such a bad place to live after all. Well, yeah. Because we now know that life exists there. You can follow that line of reasoning until we find life at the center of the Sun.
I know people think they're being sophisticated when they insist no limits can be placed on the form of life, but it's not true; it's naive. There are in fact certain very powerful and generic limits that can be placed on life with some powerful mathematics, such as the one I mentioned. It's fun to imagine a life form in science fiction that lives on the surface of the sun, but in reality they are not possible; there's no way they could retain any interesting structure in such a high entropy environment. To argue otherwise is basically to be arguing against thermodynamics. This basically puts this position firmly on the "crank" side, not the scientifically knowledgeable one.
Also, the idea that there are no limits on what life can look like is observationally false. The vast majority of places we look, we do not see life. Even if we manage to find a few simple life forms in a few of the slightly less hostile places in the solar system, it still won't change that fact; life is observationally not abundant everywhere, regardless of conditions. There definitely is a difference between conditions conducive to life and those not. Even what we call "extremophiles" are only surprising in purely local terms; in absolute terms in the Solar System, volcanic vents are still incredibly hospitable places compared to what is out there. In its own way, trying to argue from extremophiles to the general case is its own perversively parochial argument; the idea that extremophiles are actually "extreme" is a very terra-centric viewpoint.