Have we reached the point when it is kooky to not believe in massive amounts of intelligent life having evolved throughout the universe?

Great Debates
181

Well, it wouldn’t hurt to look. If there are 200 billion galaxies and none of them have become optimised for energy collection and data processing, then that would be an interesting data point. More interesting would be the detection of some or many such ‘optimised’ galaxies. There are numerous different ways to optimise a galaxy for energy collection and data processing, and I’d gladly explain as many as I can remember; but it would be intriguing to see how many of these have been realised in the observable universe, if any,

One possibility is that different galactic civilisations might ‘copy’ one another, if one of them comes up with a useful and relatively easy way to engineer their galactic environment. So if we observe a cluster of galaxies near to each other that have all been optimised in one particular way, that does not imply that they have had direct contact with one another, but rather that they have observed what the others are doing.

182

No, Sam is not saying that. He is saying he DOESN’T know, and that neither do you.

You are making a great many assumptions for which we have no evidence. Perhaps you’re right. Perhaps you’re wrong. We have no data sample to draw from.

183

In a galaxy containing millions of civilizations, someone had to be the first one to reach intergalactic technological levels. Or some simultaneously. My biggest fear is that we’re it, or in that group.

184

If you looked at Manhattan 500 years ago, you wouldn’t see any buildings. Does that mean we can rule out the existence of skyscrapers in that city?

Because when we take a view of the observable universe, we are effectively looking backwards in time. It’d be quite a thing if the reason we don’t see the megaprojects is actually because they are contemporary to us!

Naturally, of course, we don’t have any proof they do exist. But I’m not so sure that we can be so confident of your conclusion (nor do we need to start imagining things like cloaking devices - basic physics, and the insurmountable problem of distance plus finite speed, does just fine).

185

Lack of central control is exactly the reason why exponential growth or decay is inevitable. When all decisions are local, the growth rate must be proportional to the size of the population. That is an exponential function.

Hardly. Every life-form on Earth grows exponentially when resources are unlimited. Or dies off exponentially–that can happen too.

Again, it is exactly the lack of grand planning that causes this result. A bacterium doesn’t have a goal of killing the life-form it is inside. It just decides, locally, to make a few copies of itself before it dies. The same is true of rabbits in Australia or humans when they first move somewhere with abundant resources.

That some planetary societies may decide to never expand is again irrelevant to this point. If all of them decide this, the civilization will die. If some do and others don’t, then the ones that can maintain a reproduction rate above 1.0 will expand exponentially.

If a civilization can maintain some grand plan, it could conceivably control the rate of expansion. But as you noted, the vast distances make this difficult. So the only real choice is to wait for it to be self-limiting, which only happens when the population starts stepping on its own toes, or something else starts stepping on its toes. Either way, that can only happen once the galaxy is well-populated.

186

The only ‘megastructure’ we could detect in another galaxy is one which changes the characteristics of the entire galaxy. In other words, a Kardashev type III civilization.

We have no idea if such a civilization is possible, or if it is how likely it is to develop. How does a civilization coordinate activities across an entire galaxy when communication between one point and another can take tens of thousands of years? How do they maintain a coherent civilization after millions or billions of years of divergent evolution across the ‘civilization’? Does it even make sense to modify a galaxy in that way? We have no idea.

Just because we can vaguely imagine something that might hypothetically be a thing does not mean it’s actually a thing - especially since we really don’t have the foggiest notion about what it would take, what kinds of civilizations might exist, etc.

Using the absence of that imaginary thing to draw conclusions about the real universe is silly. We can’t even say they don’t exist, because the number of galaxies we have actually observed in detail to spot shifts in spectra due to megastructures is a tiny fraction of all the galaxies in the universe.

The best we can say about Kardashev III civilizations is, “Hey, you know that imaginary thing we just thought up in the last .00001% of our existence? We haven’t found any of those so far, but we haven’t really looked much.”

Most of the debates around this stuff are dealing in science fiction. The actual science we have to date is not strong enough to make any conclusions about life around other stars at all. At this moment, there could be a technological civilization at Alpha Centauri and there is no guarantee we could even discover it. Hell, there could be 20 technological civilizations within 100 light years of us and we could be oblivious. There could be a hundred thousand Dyson Swarms scattered through the galaxy, and we wouldn’t know until we get lucky and stumble across one.

I keep going back to this, but I think many people really, really overestimate our ability to detect civilizations around other stars. We also underestimate the difficulty of travelling between stars in any sort of reasonable time. Science fiction is probably to blame. We think we just need to find the proper ‘star drive’ and we can do it.

Also, have also never managed to build a self-contained ecosystem we could live in that was stable. Biospheres I and II failed. It may be impossible or extremely difficult to make miniature stable ecosystems that are subsets of a planetary ecosystem.

What if every planet that can harbor life has a complete ecosystem of its own, and creatures from another world simply can’t colonize a living world they didn’t evolve in? It’s only been the last couple decades since we realized that our gut bacteria was a serious regulator of our own complex internal systems, and we still don’t understand exactly what it does. We are part of a complex system of complex systems, all evolved together. Maybe you’d have to take the whole damned thing with you if you wanted to go somewhere else forever.

I’m not saying this is the case, and offer it only as another theoretical answer to the problem. So I don’t want to debate gut bacteria. Even more likely as a limiter (if there is one) is an unknown-unknown we have yet to discover. For example, gamma-ray bursts were unknown at the time Frank Drake came up with his equation. Now we know that a certain percentage of star systems essentially get sterilized if they happen to be in the beam of a GRB and are close enough to it. How many other things are out there that we have yet to discover that are serious limiters of civilization expansion?

Debates over the Drake Equation are fun, and the thought experiments around them could be useful and guide some research. That was actually its purpose. But we are still at the point where using it or the Fermi Paradox to draw ANY conclusions about the likelihood of other technological civilizations is not reasonable. We are starting to constrain some terms, such as the number of stars that have planets, but others are still so vague that reasonable values for them could lead to anything from zero civilizations to millions.

So long as reasonable values for the Drake Equation could equal approximately one civilization (us), the Fermi Paradox does not need an answer. Enrico Fermi never intended it to be a ‘paradox’, either.

187

Absolutely, and good observation. However, the disconnected nature of that kind of expansion does argue against the existence of Kardashev Type III civilizations, which would need to stay coherent enough to plan and carry out galaxy-spaning megastructures.

And the disconnected nature of expansion could actually be the answer to why life doesn’t expand to occupy the entire galaxy. Imagine a civilization comes along and builds the capability to expand to other star systems. As it does, it’s essentially creating competing cultures and eventually species that could complete with it for the resources available.

The result could converge to some kind of stasis that prevents further expansion. Maybe once you get to a certain point, any civilization that tries to expand into new resources is immediately opposed by its cousins, and they either learn to be happy with what they’ve got or they destroy each other.

188

This would be a very unlikely coincidence. If we search the surrounding galaxies out to a distance of 200 million light years, and fail to see any ‘megaprojects’, that represents only 0.014 of the history of the universe.

The Big Bang occurred 13.8 billion years ago, and we should not expect all the megaproject builders to only have emerged in the last 1/70th of that period, especially since stars like the Sun have existed for many billions of years.

We might also expect to see the ruins of ancient megastructures created by civilisations much older than 200 million years. An abandoned Dyson swarm would gradually collapse into a disk, but we could notice unusual spectral signatures and dust particles of unexpected size in such a cloud.

189

I don’t think this point really goes anywhere…what does “contemporary to us” mean in this context?

And if we’re going by the Copernican principle, there is no reason why our pocket of the universe should be “late” compared to elsewhere.

Of course, if you’re just speculating that maybe there are factors that make intelligent life astonishingly unlikely before 13.7 billion years, so we’re among the very first…I agree that’s a possibility and I already talked about that upthread. This doesn’t seem to be the point you’re making here though.

190

A very good point. Even if cultures in different solar systems start off very similar, over thousands, tens of thousands, or hundreds of thousands of years these cultures will probably diverge. Even if we assume very high bandwidth communication between these colonies, they are still separated by years or decades of light-travel-time distance. Such a separation would breed paranoia - all military intelligence about the nearest neighbours would be many years out of date.

191

Yes, but it is a possibility, which is why all of these absolutist statements (e.g. if we look out in the sky and don’t see megastructures, it means they were never created, or have some hidden cloaking device) aren’t warranted.

Again, for emphasis: The sheer size of the universe, coupled with the limits on speed, mean that we can never actually rule out the possibility of intelligent life elsewhere. Sure, it’d be nice to get the evidence that proves that they are out there. But until that time we can’t say it isn’t so.

What I keep reading are assertions about what those other intelligent civilizations would be doing, along with claims that they must not exist because we don’t see theses imagined things.

We simply may not have the capacity to ever interact with them. Our own perceived isolation isn’t proof that we are alone. Space is just too big.

Right now.

When we look out across the universe, we don’t see how it is right now. So not seeing something doesn’t mean it’s not there right now.

192

Sure, but multiple intelligences showing up are not the data we are trying to explain. The Fermi Paradox is the absence of other intelligences in the universe - when we would expect other intelligences, given what we know. The point is that a simulation can “explain” this (or any other anomaly), since a simulation can behave in any arbitrary manner.

193

Indeed, we are not the most responsible of species I suspect.

I concur with the above. Blind as bats we are & “interstellar Space = Neo-ocean” is wrong imo too.

194

This is all an aside (because it doesn’t really help for Fermi), but there is no “right now”. There is no true time that it really is.

195

And what I keep seeing is the opposite. People saying that because intelligent life can exist, it must exist out there, even though we haven’t seen it. I must side with those who are still agnostic. Obviously intelligent life is possible, but we just don’t know if it exists anyplace except here.

I’ll even go a step further, we don’t even have a good idea of the possibility that it exists out there.

If we find life in another place in this solar system, then that gives us an idea of the probabilities. If we’re related to the life on Europa, or wherever, then we know panspermia is possible, so there is all of the sudden the real possibility of life traveling on rocks between stars. It could have spread all over.

If we’re not related to life on Europa, then all of the sudden, on a few dozen planets, moons, and planetoids, we’ve seen life appear twice. It is likely everywhere.

If we see signs of life on an exoplanet, then I think life is probably everywhere.

I guess my belief is that I can accept the probability of life being anywhere from “once, ever” to “common” (the range now, as far as we know), but a range of “twice, ever” to “common” seems implausible. Twice and we found each other means it’s common, because the odds of only twice, but we happened to find each other seem absurd. (10 lifes in this galaxy is common.)

Right now is whatever time it was when the light we see now left. So right now on the sun is 8 minutes ago. The only reference frame that matters is my own.

196

Here’s an example: you and me. And all the modern nations on earth.
All over our planet, people have decided to “self-limit”–that is, only have one child per family.
All of the western nations have birth rates below replacement rate.

So this is one answer to the Fermi paradox, which is based on the assumption that any technical civilization will expand. It was a logical assumption, back in the 1950’s. But today, we have a simple, easily measured scientific fact which Fermi did not have: technical cultures have less babies.
In fully one hundred percent of all the technically advanced civilizations we know about (ie.–every country on earth)–once women start working outside the home, they have many, many fewer children.

So maybe the aliens aren’t visiting us because they don’t have enough manpower to staff their ships.

197

This doesn’t follow at all. A sufficiently advanced civilisation capable of building a starship which can traverse tens of light years might also be expected to have mastered artificial reproduction and nurture. In such a civilisation the population would always be the same - whatever is necessary.

198

You can pick any reference frame you like, but it is still the case that there is no real time between two distant points in space.

199

You may be interested in the video below which discusses if we are among the first spacefaring civilizations (21 minutes long, great channel, well worth a watch):

200

I haven’t seen that one yet, I did see it pop up last night but didn’t have time to watch it. But the “Grabby Aliens” thing has been making the rounds the last few months. Isaac Arthur, Frasier Cain, and Sean Carroll all have referenced it recently. Probably others I’m not thinking about as well.

But, for the most part, if does follow the arguments that I’ve made. That if there are space faring civilizations out there, they will be expanding at whatever rate propulsion systems of the future would allow. It tends to give a limit as to how many and how close these would be, or they would be here by now.