"Life in other places might be radically different from our own, and we might be looking for the wrong things"
Very possible. Something behind our imagination (e.g. Energy, Light based life forms etc.). But it is not unreasonable to expect something similar, based out of Carbon or Si that has a metabolism and senses.
Once I read a suggestion to look for life: look for an entropy source.
I think even this is a bit of an assumption. I have a sort of thought experiment that what we call physics and what our ancestors saw as angels or spirits moving the heavenly bodies _could_ actually both be true.
Life as we know it is a source of entropy but if we take the view of God as an architect/clockmaker who created the universe as a (mostly?) deterministic machine with angels being his agents, it would stand to reason angels would be orderly as well rather than chaotic. Perhaps so orderly we would perceive their invisible involvement as natural laws rather than unusual miraculous intervention people usually expect from that sort of thing.
Of course it's unprovable and even if you proved it it doesn't really contribute much to our understanding of the natural world, but it's interesting to imagine a form of life so orderly that we don't even perceive it as life but as part of the machinery of the universe.
> And just because life on earth is fragile, it doesn’t mean all forms of life have to be.
When it comes to life made out of molecules, there aren't that many viable options for "base components".
For example, carbon based lifeforms like stuff on Earth can harvest energy from food without spending too much energy while remaining stable enough to avoid falling apart.
Silicon has somewhat similar properties, but its compounds require stricter conditions to be useful for hypothetical life.
Some amount of fragility is actually a good thing. Not for an individual, but for life in general. Animals harvest "building blocks and fuel" for themselves from other life forms that should be "fragile" enough to eat. All the advancements of evolution are possible due to mistakes in DNA replication that should be fragile enough for mutations.
That's all true for life as we know it. But this conversation was about hypothetical life in forms that we haven't yet discovered, nor possibly even imagined.
You edited out the important part of that quote. Swapping out carbon for silicon is hardly imaginative enough to be worth mentioning when we are talking about potential forms of life completely outside what we might expect.
We have examples in popular culture already that are neither fragile nor organic: sentient machines.
Im not saying that the universe is full of Transformers and Terminators. Just that searching for silicon based life isn’t all that different to search for carbon based life when you consider that life is just a sophisticated machine and you can literally build a machine out of anything.
Yeah I agree with this. In practice "who knows?!" what it could look like! But in theory, given the precedence available, I think it'd likely be similar to what we know (carbon, metabolism, maybe crab-like).
I always thought it would be a cool investigation to look at the distribution of entropy signals coming from celestial bodies and group them. I'd bet there is a non-'natural' entropic signal coming from planets with biological processes on them.
It's interesting that both compression and encryption turn otherwise clearly "engineered" signals into something that's literally indistinguishable from noise, removing any redundancy or regularity.
The inverse square law means we're not going to pick up stray radio signals from an alien civilization. If you build an Arecibo-equivalent telescope (AET) in space and flew it out of the solar system our radio noise (uncompressed and unencrypted) would fade into the cosmic background at about half a light year out. Even powerful radars wouldn't be detectable much past Alpha Centauri assuming their beam even happens to sweep the portion of the sky where the receiver will be taking into account proper motion between the systems.
The only way alien civilizations will pick up each others' signals is if they're intentionally directed at those systems with highly focused emitters. If you're intentionally sending a signal in hopes another civilization will see it you're definitely not going to encrypt it. Compression also serves little purpose as there's no shared context to decompress the message.
Encryption can't hide the fact that there is a signal. Sufficiently secure encryption makes it so that any ciphertext you receive is equally likely to have been produced by any plaintext. But if you're able to observe that some ground station on Earth transmits radio to the same point in orbit, at the same time, every day, and receives a response, the fact that that is happening can defininitely be distinguished from any natural process.
By the same token, if humanity disappeared but left a bunch of encrypted hard drives around and aliens came and found them, they may have no hope of distinguishing the bits from random bits, but they'd be able to tell that no natural process encodes any kind of bits at all onto magnetic discs or flash drives or whatever else we manage to come up with.
The actual issue is what the other commenter said about the impossibility of detecting such low power radio at all.
you can observe that there is a radiation source, but if what it's emitting is nearly isotropic white noise, the most likely explanation is that it's just hot
historical forms of signal modulation like ook and fm don't look very much like white noise, because they're designed to be demodulated by circuits with 1-10 vacuum tubes, but more modern modulations can look pretty white. they'd look a lot whiter if they weren't constrained by regulation to strongly attenuate bands used by obsolete forms of signal modulation
Very possible. Something behind our imagination (e.g. Energy, Light based life forms etc.). But it is not unreasonable to expect something similar, based out of Carbon or Si that has a metabolism and senses.
Once I read a suggestion to look for life: look for an entropy source.