Do you think any aliens exist in the universe?

I hope many of them are more intelligent than us.

GenesisNemesis said:

I hope many of them are more intelligent than us.

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I hope they are better at phasing questions, anyway.

Do you think any aliens exist in the universe?​

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* I think aliens exist, but not in the universe
** I think some aliens exist in the universe, but most do not
*** I think aliens exist in the universe but if humans disappear they will no longer be aliens
**** I think aliens used to exist in the universe but the universe sucked so they left.
***** etc.

If evolution is a constant then similar planets to Earth will have similar critters.

ET lands on the White House lawn. The hatch opens and they piss out on the lawn and toss out empty beer cans, close the hatch and fly away.

What would Joe say.....?

Would the public be told?

With our luck, we'd encounter an alien race with technological wonders but no tradition of demagoguery that had fallen in love with Trump. Their space helmets would sport little orange pompadours.

This post, with its link to a scientific paper on this subject, seems also to belong here.

Note, though, that in the above, the scientist is an astronomer, not a biologist. OTOH, in my reading experience it is usually the biologists who are most pessimistic about finding alien life.

I don’t recall hearing any evolutionary biologist asserting that alien mammals are likely, but they mostly seem agree that microbial or prokaryotic life might be fairly ubiquitous.

pood said:

Note, though, that in the above, the scientist is an astronomer, not a biologist. OTOH, in my reading experience it is usually the biologists who are most pessimistic about finding alien life.

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Finding alien life requires both of two things: Alien life must exist; And we must be able to find it.

The latter is a huge problem. We don't really have a good working definition of "life"; We muddle by on Earth, where most things are clearly on one or the other side of the line (albeit with exceptions such as viruses and prions, which don't really fit in either the "life" or "non-life" pigeonhole), but on Earth we know that life is going to be not just Carbon based, but RNA/DNA/Amino Acid based, and that it will use one of a handful of metabolic pathways to obtain useable energy, ultimately (in most cases) using Adenosine phosphates as the direct carrier of energy, in cells with a set of well known organelles doing well known stuff, and separated from each other and the environment usually by phospholipid bi-layer membranes, and or cellulose exoskeletons.

None of that needs to be true of alien life. The one thing we know for sure about alien life is that it will be a long way away.

If we were living on Mars (Thanks, Elon!), and wanted to detect microscopic life in Antarctica, it would be hugely challenging to do - even though we know what kinds of soil bacteria to expect, and what kind of chemicals would be a positive signature of their presence.

The huge distances involved make picking the exact analytical tests to include on our very weight-restricted probes, to get the most convincing and definite results, really difficult.

To be honest, there are lots of people who would deny that we had found alien life, even if we brought a sample to Earth, grew it in a lab, and let everyone who wants it have some to study. If it was very similar to terrestrial life, people would say it was contamination from Earth. If it was sufficiently different, they would say it wasn't "life" at all, just complex cyclic chemistry that reproduces instances of itself.

And of course if we grew alien life on Earth and let just anyone take a sample, the Panel on Planetary Protection (PPP) at COSPAR would have kittens*.













*In the figurative sense, that is; I expect at least some of them literally have kittens, or have had in the recent past, given the popularity of cats as pets, and the size of the PPP, which currently has twenty eight members.

GenesisNemesis said:

I hope many of them are more intelligent than us.

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steve_bank said:

If evolution is a constant then similar planets to Earth will have similar critters.

ET lands on the White House lawn. The hatch opens and they piss out on the lawn and toss out empty beer cans, close the hatch and fly away.

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Like earthlings, they would not know where life exists and like earthlings, they would not be able to travel that far. Just keep wondering about it. I am sure that in this vast vast universe, life exists at many places.
Let them do pissing on the White House lawns during Biden's time, and not after Trump takes over. Trump will go and attack them. He has the support of Elon Musk.

What does ET call humans in a spaceship?

A tasty snack.

aupmanyav said:

I am sure that in this vast vast universe, life exists at many places.

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I wonder about the "icy moons" Eceladus, Europa etc.
I don't bother wondering much about stuff we'll almost certainly never know, but I am hoping that maybe in my lifetime, samples could be obtained from below the ice of Enceladus, in water warmed by tidal stretching of the moon... I also wonder how long huge water jets have been spewing from Enceladus* (its age estimates vary from as recent as 100my to a billion), and how long they can keep on spewing from Enceladus before it runs dry. Evolution generally works better the more trials it gets , and that's not much time. Earth was probably a billion years post formation when prokaryotes appeared, and maybe a billion (?) years more for eukaryotes to show up? Of course earth, presumably a semi-molten glob at the time, had more cooling to do than Enceladus. Enceladus is thought to have formed by accretion of "ring" material**, whereas the aftermath of earth's collision with Theia was pretty hot and earth's surface/volume ratio is much lower ... so maybe there have been suitable conditions on Enceladus for long enough to leave traces of something that some (irreligious) people might call "life", or little lifelike thingies?
Probably just as futile as wondering what it's like in "other dimensions" or "long long ago in a galaxy far far away", but it is fun to dream, especially if there is some shred of rational hope of finding out.

* Cassini detected organics, including amino acids in the water plumes...

** We have some astronomically knowledgeable people here (literally and figuratively) and I was wondering if anyone knows about when in the presumably gradual process of accretion, a body like Enceladus is declared formed? Is it arbitrary? When it stops gaining mass to some specific degree?

steve_bank said:

What does ET call humans in a spaceship?

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Dave.

Elixir said:

steve_bank said:

What does ET call humans in a spaceship?

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Dave.

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Dave's not here.

As this is pseudo science, all's you have to do is turn on a light on the back of the spaceship and away you go. They do it all the time in scifi movies. Works great.

Unless there is something we are unable to imagine or detect, we are stuck here, and the same for ET.

If there are a lot of ETs similar to us in technology, then the universe must be fulled with all those deep space probes.

Elixir said:

I don’t recall hearing any evolutionary biologist asserting that alien mammals are likely, but they mostly seem agree that microbial or prokaryotic life might be fairly ubiquitous.

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But such life would be basically impossible to detect without going there. There seems to be a fair agreement that some of the big moons of the outer planets might be life bearing. We don't even know over such a puny distance. Unless there is radically unknown physics involved K2 civilization can be detected at near intergalactic range.

Furthermore, such life can't spread. We can't see most of our own galaxy to see what's there.

Elixir said:

.. so maybe there have been suitable conditions on Enceladus for long enough to leave traces of something that some (irreligious) people might call "life", or little lifelike thingies?

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Sure, possible, and probably within our reach (to know, not that we might be able to go there). I do not think humans will travel outside the solar system.

Loren Pechtel said:

We don't even know over such a puny distance.

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We could take it as support for the idea that life is not particularly rare in this neighborhood of the galaxy.

aupmanyav said:

Elixir said:

.. so maybe there have been suitable conditions on Enceladus for long enough to leave traces of something that some (irreligious) people might call "life", or little lifelike thingies?

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Sure, possible, and probably within our reach (to know, not that we might be able to go there). I do not think humans will travel outside the solar system.

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Heh, I doubt there will be many who go beyond our binary earth moon system, and doubt even more that they’ll be coming back. But if there’s life within range of our ability to explore, I’d love to know for sure!