[vjjsejj]

> but isn't using this definition extremely limiting?

So instead for searching something specific (we sort of understand) we should spend time and resources looking literally for nothing in particular?

Also I don’t non-carbon/water lifeforms are at all compatible with our understanding of biology and chemistry?

[jerf]

I have never seen a convincing basis for life that isn't carbon. The next best candidate is silicon, but it seems like the problems are unlikely to be overcome.

Non-water may be just about possible: https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemi... Non-water solvents may run at somewhat different temperatures.

However, strongly showing that an alternative is possible is a super, super uphill battle. If we weren't made of carbon and water, I'm not sure we could conclusively show that life could be built on it. But we probably couldn't disprove it. Ammonia is probably at least in the "not disproved" category. But I think most everything else is. If you seriously think about it, beyond the "my mind is so open it's falling right out", it's a pretty tall bar to find an alternative. (If you don't think so, spend some more time with organic chemistry, and consider why we call it that. There is a reason life is based on it, and there's a reason we cleave the entire chemistry world into two pieces along that division.)

It is also in my opinion not that interesting a question ultimately. The big jump is the one from zero possible life substrates to one. Having a second one doesn't really change much, e.g., I don't see any compelling reason to believe there would be an "ammonia solvent" view of the universe versus a "water solvent" view of the universe or something.

[stinos]

looking literally for nothing in particular

That's not what I said. My last question covers this exactly: are there metrics other than 'conditions like we know them' which can be used? Maybe the answer is just 'none that we know of', again: no idea, and yes then one cannot look for it. But here on earth we can distinguish between a rock and a cell based on various metrics. They way they reflect light is perhaps different enough to tell that one is a relatively simple solid consisting of chemical bonds which are all alike, whereas the other one isn't. Or processes in the cell make the atmosphere slightly different. Now suppose some other lifeform also consists of cells but instead of water-based they use something else which happens to be liquid at 200 degrees Celcius. A rock can still look like a rock at that temperature and maybe won't alter atmosphere. Maybe something living would?

Also I don’t non-carbon/water lifeforms are at all compatible with our understanding of biology and chemistry?

It's not because we cannot understand it that we cannot observe it. In fact that's usually how it goes: first observ, then understand. Isn't that basically what we're doing already with a lot of telescopes/wide band radiometry/... ? Looking for things without understanding how they can exist or where they came from (the OMG particle etc)