Fermi’s Paradox notwithstanding, is it still obvious that there are advanced ET’s out there?
Notice I use the word ‘obvious’. And I put this question in GQ.
No, it’s never been “obvious.”
If it were obvious, it wouldn’t be a question, would it?
Sure, for large enough values of “out there”. The Universe may well be infinite, and even if it’s not, it’s still really, really big. Even the most pessimistic estimates of the probability of life, or intelligent life, on other planets are still high enough that we would expect multiple instances within the entire Universe. The relevant question is not whether they exist; it’s how far away they are. There might be other life elsewhere in our Solar System and intelligent life at tau Ceti, or it might be that we’re the only life at all in the entire local group of galaxies. Though, granted, for all practical purposes, that latter possibility is awfully close to “there isn’t any other life”.
It’s obviously not obvious. Our own planet has had billions of species come and go over past billion-plus years, and as far as we know, only one has ever evolved to what we might call “advanced” (and even that one seems to becoming more and more questionable).
People have advanced hundreds of arguments that would explain why we haven’t seen advanced ETs even if they exist.
We don’t know the answer. We can’t extrapolate from one data point.
We can’t even figure out what the word “obvious” means in this context.
Now that we know that most stars have planetary systems, and many of those billions of planets will be element-rich like our earth, finding life elsewhere seems a pretty safe bet.
However, “advanced ETs” is a different story. The whole point of the Fermi paradox is that, based only on what we know right now, we could be justified in expecting to have seen evidence of them already. Sure, there are lots of potential explanations for the lack of such evidence. But the point is, trying to explain the lack of evidence, is a very different place from it being “obvious” that they must be there.
What evidence would we expect to see of life elsewhere?
What evidence would indicate life elsewhere you mean?
There’s the obvious, if they are intelligent, and we start picking up their radio signals. Start picking up the “I love X’charni’tc” show, and that’s a pretty good indication.
As far as life, we may be able to, with the next generation of space telescopes, start making out spectroscopy of the atmospheres of exoplanets. There are certain bio markers that would indicate the possibility of life, though not a certainty.
The hubub of phosphine in Venus seems to have come mostly come to an end, largely because the detection of the chemical itself seems to be in doubt. But, even if the presence of phosphine were confirmed, it still wouldn’t prove life, as there may be other processes that create it.
The same with large amounts of oxygen, if we see a planet that seems to have abundant oxygen, then that’s a pretty good indicator of life, oxygen doesn’t typically stick around all that long. But, it could be a different process creating it.
Basically, as big as the galaxy is, it’s hella old. There has been plenty of time for ETs to far exceed human progress and clutter the galaxy with bric-a-brac like self-replicating probes, generation starships and a whole host of various mega projects. We don’t see any of that. And this is assuming FTL is impossible, the paradox gets much worse otherwise.
ETA: Oh, how did I forget radio (or other) signalling 
Thanks k9bfriender
The first impulse of many people is to jump to one of the potential explanations for the dearth of evidence. And. like I say, there are many of these.
But this doesn’t take from the fact that, right now we’re trying to explain why it looks like no-one has even touched the cookie jar, and the OP is asking “Is it obvious that someone has eaten the cookies?” No, no it isn’t.
Might I ask when it was obvious? I don’t think it ever was.
Maybe a few people accepted Giordano Bruno’s argument that the multiplicity of worlds implied that there was life on all of them, but most did not, and look what happened to him. Later some people may have accepted the Great Moon Hoax of 1835, and to those people the answer would have been obvious. But few, if any, astronomers fell for that one.
A larger number of astronomers, and writers of speculative fiction (like H.G. Wells) were convinced by Giovanni Schiaparelli’s observations of canals on Mars, and even the skeptics seemed to accept that Mars was probably populated by simple lichens or other biota. This was all dispelled by the first pictures beamed back from Mars’ vicinity, which showed a cratered, barren planet. I remember when that happened, and perhaps that was the last time that anyone could have ever have said that the existence of extraterrestrial life was ‘obvious’.
But what do you think?
The way I see it, there are 4 significant steps that need to happen:
- Life itself (we can’t really say for sure how likely this is, as we only have one example, but it happened early here - pretty much as soon as the conditions were favourable)
- Complexity - in our own example, multicellularity but perhaps other alternative methods of complexity are possible (given the apparently very long time this took to figure out here on Earth, it seems complexity might be less likely than the formation of life)
- Intelligence - this has evolved independently at least twice on our own planet - vertebrates and cephalopods (so this seems likely, after complexity has happened)
- Technology - this depends on a lot of environmental factors - intelligent life that can’t leave water is going to struggle to master fire; intelligent life the size of beetles is going to struggle to smelt metals; intelligent life that arises on a planet where the crust has been fully recycled many, many times may not have the same mineral resources we have been lucky to exploit.
If there are other civilizations in our Galaxy, then we would expect them to have spread throughout the Galaxy by now: That’s what Fermi’s paradox is about. And maybe, if there were other civilizations in the Andromeda Galaxy, they might have been able to spread to our Galaxy. But that’s where it ends: It is not plausible for another civilization to have spread to the Local Group (those two galaxies plus assorted smaller galaxies orbiting them) from outside of the Local Group. So one possible resolution to Fermi’s paradox is just that civilizations are so rare, that we’re the only one in the Local Group.
But “so rare that there aren’t any others in the Local Group” is not the same thing as “nonexistent”.
It’s not obvious to me that we can expect other civilizations to spread to multiple star systems. I think the most likely solution to Fermi’s paradox is that c really is the speed limit to the universe, there’s no such thing as warp speed, and the challenges of interstellar travel are truly insurmountable.
That said, the idea that out of billions of plants circling billions of stars in billions of galaxies, this one planet would be the only one where conditions were right for the development of a technological species, is absurd. Certainly there are other civilizations out there, but we’re never going to meet.
That’s because you are not thinking large enough, in terms of time or in terms of technology.
Once we have established our first self supporting asteroid colony, there is nothing in our way to spread out to multiple star systems, eventually filling the entire galaxy. It does not require FTL to accomplish this.
So, either there is something that would prevent us, and anyone else, from expanding into space, or we are unique, in either we are the only ones who exist, or the only ones who would expand.
I find it much more absurd to assume that there are other civilizations out there, but we are the only ones that would expand into the galaxy.
Of course, you did say, “in billions of galaxies”, and that’s a different matter. Within the local group, it seems very unlikely that there are any other technological species, as they would have expanded and reached us by now. Outside the local group, in those billions of galaxies, is a different matter.
A potential answer to the Fermi paradox is that we will never establish that self sustaining asteroid colony, but the only thing that’s in the way of that is ourselves, if we manage to wipe ourselves out before achieving that. If we do wipe ourselves out, it could be reasonable argued that any world that develops a technological species ends up on that same road. Harnessing the energies required for space travel also means harnessing energies that can be used for war, and inevitably also means having the ability to modify the environment, intentionally or not.
It very well could be the case that there are billions of dead civilizations out there, that made it to around our level of technology, before dying off by the same threats that we face.
Really, the Fermi Paradox boils down to that we are either the first of our kind, the first technological species in the local universe, or we are simply the latest in a long line of failed and now dead civilizations. To be honest, optimism is the only reason I favor the former, as there is really no evidence to eliminate the latter.
Those are two possible resolutions, but they’re not the only two. Another one, for instance, would be that the other civilizations are out there, and have spread, but are deliberately keeping their presence hidden from us for some reason (for any civilization with the tech level required to spread, keeping themselves hidden from the likes of us would be easy).
But yeah, a lot of people misunderstand the premise of the Fermi paradox, because we just aren’t equipped to think in terms of the numbers required. Sure, it would take millions of years to spread throughout the Galaxy, but you shouldn’t conclude from that that it’s impossible, because on the relevant timescales, “millions of years” is actually really, really short.
Keeping hidden from ourselves means not just not revealing themselves in our backyard, but also in their own as well. We may miss one or two Dyson spheres out there, but the kind of astroforming that would be trivial to such a civilization would become quite obvious. There’s gotta be a couple giant stars out there that are getting ready to go supernova uncomfortably close to some civilization’s system, and a Shkadov thruster should be visible from halfway across the galaxy.
It’s only if they are staying hidden, paranoid that anyone knows that they are there, that they would be hidden from us. The Dark Forest Hypothesis, essentially.
As a coordinated effort, they may be able to pull off the Zoo Hypothesis, doing their best to avoid their detection as the observe us. I can see the reasons behind this, an undetected civilization may have unique creativity that is lost once it joins with the rest of the galaxy, and it may even be the case that the best burst of creativity comes at the moment that that civilization joins, combining their unique perspective with all of the knowledge that is now available, and that our “caretakers” want us to be as ripe as possible for that harvest. Still hard to pull off, but if the motivation is great enough, may be possible.
We may be on the edge of being able to detect them, we are going to be be able to start seeing much more clearly once JWST goes up. If Space X stays on track, we should be able to start sending up better stuff than James Webb here soon. It won’t be long, in the grand scheme of things, before we are able to directly image exoplanets. If they are going to reveal themselves, it’s probably going to need to be pretty soon.
There is no evidence at all that there are other civilizations anywhere in the entire universe, or that there ever has been. Likelihood, probabilities, hopes, and Star Trek dreams mean nothing. There continues to be no evidence at all.
Until other facts come in, we have an occurrence of 1 example of intelligent life in the universe. How otherwise supposedly scientific minds continue to ignore the obvious is a stain on reason and the scientific method. Evidence = one example, us. Evidence of others = zero. That’s it.
Why should we expect that? Let’s assume a few things were different here on Earth, things that would lead to us being more likely to establish human life elsewhere. Maybe humans evolved to be more cooperative, and our current civilization turned out to be a Star Trek TNG style utopia. Maybe Earth’s gravity is a bit lower so that we have a lower escape velocity. Maybe we have larger deposits of uranium that we could use to have a much more extensive system of nuclear fission power. Even with all that, it seems extremely unlikely that living humans would ever be able to reach even the Alpha Centauri systems, much less anything even in the double digit light years away.
“Never” is a long time. Maybe it’ll take us a thousand years before we leave on the trip. But a thousand years is a far cry from “never”.
@Dallas_Jones, of course there’s no evidence, once you disregard all of the evidence. What do you think any evidence ever provides, other than probabilities?
The Fermi paradox is one of the most frustrating topics here at the Dope, because it’s always at least 75% of people with misconceptions about it.
All it is saying is, that based on what we know: about physics, about the age of the universe, and about intelligent species (for this, all we can do right now is look at homo sapiens as an example) we may expect to see evidence of advanced ETs. It’s not that nobody can think of any potential explanation why we don’t see that, but any potential explanation right now is speculation; going outside of what we know.
Why do you say that?
Bear in mind, we’re not talking necessarily about humans physically going to alpha cen and planting an Earthican flag. For the Fermi paradox, we’re talking about any probe, any signal, or even any changes to Earth that would be detectable. Alpha cen is a bad example for your point, because we would be able to detect radio signals from there, and in terms of probes, we’re already capable of sending a slow probe that could reach alpha cen within “mere” millions of years.
Sure we haven’t launched anything at alpha cen yet, but give it time, we’ve only been a spacefaring species for one human lifespan.
Ignore what? You want scientists to declare there is no intelligent life out there? Why would they do that?