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Comment by citizenpaul | Hacker News Reader

I'm a firm believer that we will never meet alien life beyond a microbe.

Also I'm on the side that we are likely the only life active in the universe. As it is said by many scholars life should be common. If life is common. If indeed it is possible for life to spread across space it should overrun the galaxies by now. Even at sub-light speeds. However it clearly has not. The in the face obvious conclusion is that these speculative theories are wrong and life is not actually common and life does not spread easily. I'm not sure why so many other people are dedicated to believing the opposite of this with no actual evidence beyond theory.

Yeah dark forest theory. Yeah forerunner theory. I've heard them. Maybe...

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Also possible that life requires a certain amount of universal "cook" time, and that while it's extremely common, and extremely local, we will never see if because we are stuck in our temporal frame, and the only thing that will observe the out-radiation out lightforms are black holes or the heat death of the universe. The universe is extremely empty, but it may also be extremely cluttered / noisy for the ability to observe other life.

I think it's perfectly reasonable to assume that life naturally comes to the conclusion that it doesn't make sense to try to extend beyond its gravity well, or have a quiet death by trying "too hard," expending the resources available trying to propagate beyond.

What about Kurzewei's take that it's our duty to "colonize the universe with intelligence"?

Take that universe.

Yeah ... even if the majority do not choose to do so, the minority will suffice to fill the universe with e.g. Von Neumann probes.

Perhaps. But I guess what I was saying was that, given that the expansion of the universe is accelerating, it may be physically impossible to propagate outside a local area, given a universal speed limit. An event horizon outside of which no information can escape, and where attempting to do so merely increases the dispersion of energy. Ie, a localized acceleration towards heat death. The universe can be totally full, and noticing it can also be outside our possibility of observing it, ever.

So there are a few things to this. We don't even know what life is fundamentally, beyond a continuing entropy generating process. By that logic the storms on Jupiter are alive.

Then there's consciousness. What even is it? Who knows.

There is Wolfram's principle of computational equivalence, which implies that we wouldn't even know life if we were looking right at it if it didn't evolve with us.

And beyond that, do you think a beetle on a leaf knows you're looking down at it, does it recognize that you have a face, is it even capable of comprehending your motivations or knowing you have them at all? When an ant is walking on your arm, do you think it knows it's on a living creature and not a wall? Can you tell me what bacteria are floating in front of your eyes right now and their natures?

That's a thought experiment to drive home a point: we could be surrounded in the universe by agents, consciousnesses, life, big and small, up to all kinds of things interesting and uninteresting, we could even look right at them and still have no idea what we are seeing or that they're even there.

In the end I come back to where you are, but from a different angle. I don't think we will find life because I don't think it even matters to us, because we won't even be able to recognize or comprehend it if we did see it. It could be everywhere or it could not be there at all and I don't think we could ever hope to tell the difference.

By the same logic, we could be looking at a computer system turn into an agent, and we wouldn't notice it.

life is not an entropy generating process. All processes generate entropy. Life locally reduces entropy (but of course globally generates it, like all other changes).

As for this,

> In the end I come back to where you are, but from a different angle. I don't think we will find life because I don't think it even matters to us, because we won't even be able to recognize or comprehend it if we did see it. It could be everywhere or it could not be there at all and I don't think we could ever hope to tell the difference.

I kind of agree with you. A lot of the 'alien' stories I read about seem to have stories eerily similary to movies and books that preceded it. For example, some on reddit are convinced that aliens want to save us from climate change. The unanswered question is why would aliens care? or nuclear proliferation? Again... that's the plot of a movie.

What I would like to know is how good is our ability to actually detect life from afar? For instance, we only discovered water on local planets and moons within the last decade or two. How loud do aliens need to be for us to notice them?

If we were near Alpha Centauri, would we be able to detect life on Earth? Would a SETI scan of Earth detect our radio waves or other signatures of life?

If we’re going full speculation -

Microbial life is probably not too uncommon, almost certainly present in our own solar system beyond Earth (and then the big question - does it always originate on its planet, or is cross planetary contamination a thing?)

Complex life that can build tools to send itself to orbit is probably a whole deal less common, but we’re not the only ones nor the first ones in the universe.

It’s just that the scales (time, distance, energy) involved are so wild that the odds of any 2 forms of life encountering each other is practically 0.

Well, if cross contamination between planets is a thing, the most likely way for 2 such complex life forms to interact would be for them to have developed in parallel in the same solar system, and then one discovering the other.

your argument could also be used to reject most of earth science. we will likely never, at least in our lifetimes, go to some other planet that is in any way like earth. Therefore all of earth science is simply observations of what is in front of our faces when the universe is likely different.

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