I understand it would be super interesting to find biological processes similar to earth like life similar to our light, water & dioxide cycle (im sure there's a name for it)
But sometimes it sound like many people think that's the only way life can start, yet we have no idea how it really works. Also on earth there are organisms in the deep sea that have completely different biology. We might find life, even sentient one, in places we haven't thought to look.
I'm on the more pessimistic side of this argument. Lots of very smart people have thought about this, and really the only element that is able to form complex molecules besides carbon is silicon, and there are good arguments as to why it's a much worse basis for life. And if you have carbon-based life forms, you will have water and CO2.
In any case, it is just way more likely than any other form and makes absolutely the most sense to look for this first.
Sure, you can always say that we don't know what we don't know, but the periodic table of elements is finite and complete, and we are pretty sure that chemistry doesn't change across the universe. I realize I'm fighting an uphill battle in my position, because it's hard to prove the non-existence of things, so you will always be able to say "whatever, maybe you didn't think of everything", and it's true, but I have a hard time seeing how life can be anything but carbon-based. If you have more insight besides what resembles a god of the gaps, I'd be very interested.
Yeah that make sense, but still very much earthlike biology perspective. I mean almost everyone here also believes in digital intelligence at some point.
Are there elements that are more stable under high pressure or heat? Or opposite?
> Yeah that make sense, but still very much earthlike biology perspective.
What does that mean? The parent’s point was that this isn’t just a matter of looking for what is already familiar, but a matter of through the lens of what affordances the elements have and therefore what, in principle, is likely or even possible, to the best of our physical/chemical knowledge.
There’s a rational middle ground between parochialism and anything goes.
Worth noting that even "digital" doesn't mean "not carbon". The current likely end-state of electronics is likely moving from silicon back to carbon due to abundance and durability.
People are working on diamond-based semiconductor devices, and organic-transistors are built experimentally all the time (nothing commercial but it's an area of active research).
An advanced bit of nanotechnology that could self-repair would likely consist of a computer chip which fabbed up replacement organic components for itself and could transport and replace them in-situ, even if it was still just a computer otherwise being digital - after all, that's how our cells do it.
Sillicon is actually significantly more common, so relative abundance isn't a good reason to use carbon. Carbon would be used because it performs better
Maybe in earth's crust, but on a galactic scale carbon is more common.
But they're both one of the most common elements either way, so I think other properties would be more important.
The way the GP comment describes carbon-based technological life made out of transistors doesn't sound like the metabolize carbon to CO2 or would require a lot of water, though, which are two important markers when searching for life.
I would argue abundance based on CO2 being a fairly common gas and "easily" processed. Silicon in silicate minerals is common, but it's much harder to crack out of them.
I'm up for it, but since you are the one who proposed we could have unimaginable forms of life, and I'm coming up short, I'm relying on you (or anyone who holds your position) here to be the creative one.
What's more likely is finding carbon-based life of opposite chirality from the left handed kind native to Earth. This would make life from each planet fundamentally incompatible with each other in numerous surprising ways.
Doesn't this depend on the STP of the alien environment? It seems plausible that planets that are a few hundred degrees warmer might benefit from silicon based life, no?
Kind of a tangent but I'm really interested in why statements like:
> if you have carbon-based life forms, you will have water and CO2.
..can lead to statements like:
> it is just way more likely than any other form
I totally agree on the observation, but what is fascinating to me is why a deductive statement can be considered to indicate likelihood in probability. It seems there is a bit of abductive reasoning going on behind the scenes which neither the deductive logic or inductive probability can really capture on their own.
I don't see that particular statement "leading" to the second statement. You quoted very selectively and didn't quote the part that is the reason why I believe carbon-based to be much more likely, i.e. the fact that silicon is such a bad candidate and that no other molecule allows complex chemistry. Maybe that helps with your fascination. Obviously I skipped all the actual arguments, but they are easy to find by the interested reader in standard literature.
You're right. Absolutely, completely correct. There's almost certainly other ways life can start. Other processes that can result in intelligence. Other paths of technological development.
The issue, as I understand is, is that all of those are completely unknown. We have absolutely no useful idea of how to look for wildly different life in places we haven't thought to look.
What we do know with certainty is that Earth's chemistry can result in life. We do know that it can result in intelligence. We do know what paths our technological development took. We even have some idea what these things might look like from afar. All together, we have exactly one data point that lets us search for similar data points.
Are there other, different world, with different life? Very possibly. We humans are well aware of this. We just don't have a way of knowing if we've found anything. So as a matter of managing limited resources, there's a tendency to stick to what we know can work.
It may just be a failure of the imagination, but on the face of it the only chemistry that could feasibly make organisms is organic chemistry. That's not because it's Earth's chemistry, but because carbon is a very useful lego brick. This leaves us looking for alternatives beyond chemistry, something like Douglas Adams's "sentient shade of blue", except imaginable and not nonsense. So your certainty about this is ... staunch, let's say.
I'm doing my best to tell this user that their imagination is possibly on to something, but mostly this is a waste of energy. I'm exaggerating the realistic possibilities to help them feel good about themselves because it makes it easier to sneak in the idea that this is not a useful or productive line of thought.
The approach of "Smart people have thought of that, there are very few chemically useful alternatives" is the kind of thing that entrenches a person in their insistence that this is just a wide-scale failure of imagination. Witness their comment about "earthlike biology perspective". They want to believe a wider, weirder universe is possible. As a rule, it helps people feel heard to tell them they're right about something.
So yes. I'm going to present it as a staunch certainty that something else is possible but currently unknowable, invisible, and irrelevant. I'm doing this in the hopes that the message gets through that this is not simply parochialist arrogance at work, from which they might nobly dissent.
>but on the face of it the only chemistry that could feasibly make organisms is organic chemistry.
First order life, but what about second order?
If I make a complex 'mechano-computer' that can reproduce itself, how exactly is that different from life? Now it looks like the universe doesn't have any direct way to go to silicon based life, but indirection over carbon based life first seems very possible.
"on earth there are organisms in the deep sea that have completely different biology": Not sure what you mean by that. There are bacteria that metabolize different things than what the bacteria up here metabolize, but they (and we) all use DNA, and with a couple exceptions they use the same codons to encode the same amino acids and start/stop. As far as anyone knows, that coding is completely arbitrary, i.e. the codons could have been entirely different. The fact that they are not entirely different implies a common origin.
You don't have to look for oxygen etc that are the signs of earth-like lifeforms. I have no idea what prohects like this look for specifically, but any kind of thermodynamic disequilibrium that shows up in the atmospheric makeup of a planet is potentially a sign of life. Free oxygen is a very good candidate, but not necessarily the only one.
But sometimes it sound like many people think that's the only way life can start, yet we have no idea how it really works. Also on earth there are organisms in the deep sea that have completely different biology. We might find life, even sentient one, in places we haven't thought to look.