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
281

We’ll have to agree to disagree on that one. I personally find it a highly implausible significant filter.

Remember, we’re talking about spans of time hundreds or thousands of times longer than all human history.
In the first 1x human history, we’ve learned to mine, smelt and refine…all of the metals, while along the way inventing polymers, alloys, allotropes etc…all of chemistry and metallurgy in fact.
Plus crude enabler technologies like digital fabricators and probes that can land on asteroids.

So what innovations do you think might conservatively be possible after 2x Human History (HH)? How about 20HH, 2000HH?

Now this is normally the point where someone will point out that no level of advancement can achieve things which are physically impossible. But you have (rightly), not bitten that bullet, and just suggested mining asteroids in situ to be really really hard. But, in this context, so what? I mean, if it’s possible to solve, how many HHs would you estimate?

I guess the movie Armageddon was right all along. The one and only way to drill an asteroid is to send a grizzled bunch of salt-of-the-earth American oil-well engineers. Just like the asteroid; they have a tough exterior but a heart of gold… :smiley:

282

I think it’s impossible to say. I also think it’s a bad assumption to believe that progress in technology will continue at the rate it has, or at all. Throughout human history most people died in a world almost identical tomtye one they were born into in terms of technology. We are living in a special time that may not last.

And sometimes technology runs backwards. Damascus steel was a technology lost for a long time, as was Roman concrete. After the heights of Rome we spent a long time in the ‘dark ages’.

Maybe we are heading into a glorious future filled with technology we can’t imagine today. Or, we might look back at this time as a ‘golden age’ full of technology we no longer have the capacity to create.

But there are more fundamental problems, such as the energy required. It’s easy enough to figure out the kinetic energy of a mass at speed, and for interstellar velocities it is immense unless you want to take tens of thousands of years to get where you are going. that brings a whole new set of issues.

I’m not saying self-replicating probes are impossible - I’m saying that we can’t take their existence as inevitable.

283

It’s not an assumption that I need to make, per se.
I am saying that the position that ETIs might be relatively common, but none is ever capable of making self-replicating probes, requires positing that technology always maxes out not much further than humans’. In which case the primary filter is really whatever factors cause civilizations to always fall.

Which is fine if that’s what you’re saying…this is a standard, well-known Fermi paradox solution.

Personally, it’s not one I find convincing as, like I say, humans are extremely aggressive, yet we are very close to being able to make tech that would be detectable to other species.

284

Really the only one who is positing “none” or “always” is you.

Everyone else is merely positing that we don’t know how effective of a filter that specific piece of Swiss cheese is. Or how effective it would need to be to have us not detect ETIs that have existed or do exist.

We have no idea how many of the planet’s capable of developing life have done so. Or how many of those that have have developed intelligent life. Or if those how many have developed intelligent life with civilizations, if any of those how many then reach our point, and how many of those, if any, have lasted long enough to develop what you propose, assuming such is possible given a large enough n lasting a long enough time.

Even if most planets that develop life will eventually reach that point we don’t know on what time course: we could be first out the gate for all we know, hundreds of thousands or many millions or a billion of years ahead of others.

Or maybe there are a thousand ETIs but less than one in a thousand go beyond where we are, let alone to the points you imagine. The dice need to keep rolling to get there even if they will eventually.

That said my biggest problem is the mindset that reminds so much of those pictures of evolution leading to us linearly, like we, and what we imagine we might become, are a target.

Even among hominids our civilization producing line is just one branch of a complicated bush, not the destination but one freak occurrence in the long history of hominids let alone of the planet. Life doesn’t need intelligence, intelligence doesn’t necessarily produce civilizations, civilizations don’t necessarily produce our sort of technology, our sorts of technology do not necessarily have to produce a desire to spread the planet. Presuming that we are the archetype seems arrogant to me. We may be more a freak.

285

And all of that still doesn’t take into account the L of the Drake Equation—how long the aliens are doing their high tech thing. Even if intelligence producing planets are fairly common, they have to occur at a time and place where the signal can reach us while we’re listening.

Even if L is millions of years, the galactic civilization could have died out and their self replicating probes gone cold a billion years before JWS produced it’s first image. The last light from that bright star that was made to pulse the first 20 digits of \pi in binary reached earth 200 million years ago, and we just missed it.

286

I don’t get how this follows.

There is one side that says that no civilization will ever expand beyond their solar system or build megastructures, and they base that on the reasoning that they think it’s hard to do for us now.

Then the other side says it only takes one that does expand or build megastructures for us to be able to notice it. It’s not saying that all will, it’s simply asking the question as to why none have, if they are out there.

No, they are imagining slices of swiss cheese in front of us, but don’t do anything to explain what they are actually made of. It is said that we will not expand beyond our solar system or build megastructures, but doesn’t give any reason in physics or technology other than that it seems hard to us today.

Every argument is one that comes from a point of incredulity, but is not based on actual fact.

Show me the barrier (metaphorical or literal) that surrounds our solar system that walls us in.

What we do know is that none have done anything that would get them noticed. They have not expanded beyond their solar system or built megastructures.

Unless you have a firm date on the expiration of the human race, you have no reason to think that we have such a limited amount of time.

That is actually the main argument that I believe @Mijin is making in this thread.

One in a thousand is still enough to have filled the galaxy before we ever got around to working with bronze.

It requires a very delicate balance to say that there are lots of civs out there, but exactly not enough for us to have noticed them yet. I’ve never been a fan of fine tuning arguments.

It’s not humans, hominids, or even animals. Life itself spread across the planet, filling every nook and cranny it could find a foothold in. The drive to expand is not something inherent to humans, it is something inherent to life.

You are not positing a different culture, you are positing that there is a form of life out there that not only didn’t expand to fill its environment, but also somehow went on to develop intelligent life.

Presuming that, out of all the civs that you are implying are out there, that we are unique seems far more arrogant to me.

What would cause it to die out? What are you positing that killed every single inhabitant, destroyed every single colony and world that this civ settled? Once again, this is making some extreme fine tuning arguments, that something came and wiped out a multi-system civilization, but we were not affected or even noticed.

287

A common refrain in Fermi Paradox discussions is “if ETIs exist, then we would see evidence of them because of “?”." The “?” is typically SR probes. This is followed by, “you have to account for each and every ETI to explain why we don’t see the evidence.”

Example: If ETIs exist, you can’t use X, Y, or Z as a reason for us not seeing their presence because you would have to account for all of them adhering to X, Y, or Z for that to be true. “All of them” assumes a very large number (thousands > billions > infinity).

But, we’re not dealing with numbers anywhere approaching infinities. For all intents and purposes, we’re dealing only with the ~100-billion stars in our Milky Way galaxy. As @Sam_Stone mentions, Kardachev Type III civilizations don’t appear to exist. I think that’s a reasonable assumption. So, seeing evidence of ETIs in other galaxies is out of the question, and seeing direct evidence of them in our galaxy in their vicinity is unlikely.

So, in the MW, we are dealing either with many ETIs, few ETIs, or no ETIs. I think we can rule out “many ETIs” because surely at least one would would overcome X, Y, and Z and we would see evidence of their existence. But, we don’t.

This leaves us with few, or no ETIs in our galaxy. Many argue that if there aren’t many ETIs, then there must be none. They don’t entertain the thought that there may just be a few (in the MW).

If there are a few ETIs, then it is not unreasonable to assume none of those few have overcome X, Y, or Z reasons for our not seeing them. Example: if there are millions of ETIs within range and time, surely some will have mastered detectable SR probes and seen fit to launch them. But, if there are only a few ETIs, it’s not far fetched to conclude that none have launched SR probes for any variety of valid reasons.

I don’t believe there are many ETIs in the MW for this reason. But, I don’t believe there are none either. I believe there are a few. Perhaps this is wishful thinking, but out of a sample of ~100-billion, I think some ETIs have emerged in the MW and some may be our time-frame sphere. But, we haven’t seen them…yet. It’s like Mama Bear in Goldilocks and the 3 Bears: not too hot, not too cold—just right (i.e. conditions for a few ETIs).

I don’t believe there are many ETIs, because we would see evidence if there were. And, we can safely assume that the evolutionary pathway to advanced tech civilizations is a rarity, even in a sample size of ~100-billion. Reasons for this are mentioned in this thread and elsewhere. It’s not like slapping together a sandwich in your well-stocked kitchen, it’s more like preparing an 8-course meal in a sparsely-stocked kitchen on fire during a hurricane (not easy, but not impossible).

On the other hand, I don’t believe it is so rare as to be nonexistent in the MW. For one thing, we have us goofy humans. We are on the verge (hopefully) of going interstellar. If it happened once in 100-billion, it probably happened twice (or 3 or 4 times). Maybe we’ll make contact tomorrow. Appease them with a nice 8-course meal so they don’t vaporize you with their ray guns, or probe your backside without lubrication.

288

All I’m doing is inventing names for the slices of Swiss cheese. All we have now is one fact:
We have not seen any evidence of alien life, let alone intelligent alien life.

Lots of people think that we should see alien life all over, so they like to argue with the some of the reasons we’ve thought of for why we don’t see alien life. The reasons we don’t see it could be right or wrong, it still doesn’t change that we don’t see it.

They don’t have to die out, just go dark. And to put that in perspective, we’re dark. We send out a few low power radio waves, that don’t go too far, but we haven’t done anything that can be seen from thousands of light years away.

Why did they go dark? Perhaps aggressive predator species came and ate all of the civilizations that were bright enough to be detected. It doesn’t matter why, we’re just writing sci-fi short stories here, because all we have is lack of evidence.

Just because the best things we can think of now are solar system wide megastructures detectable from far away doesn’t mean that is actually the best way to use energy and resources. People keep talking about tech far advanced from what we have, so it doesn’t have to be tech that we can imagine, but just don’t know how to build. It can be tech we haven’t even though of yet, which perhaps is not detectable from far away.

And yet again, people keep talking about these alien intelligences as if they exist in the same time as us. An intelligent species 2000 light years away had to be sending signals 2000 years ago for us to see them now. That same group would have had to start sending their self replicating probes much more than 2000 years ago for us to see one here.

Intelligent aliens will be separated in both space and time. Which is the more parsimonious assumption: civilizations are effectively immortal, and will exist forever once they reach a certain technology level; or civilizations may fall for any reason?

289

And the simple answer is that none have made through all the potential filters (none necessarily absolute barriers, most likely semipermeable) to having us be able to observe them.

And this is where the persistent talking past each other occurs. What is said is that there is no more reason to believe it is even possible than that it is not. The argument from “a point of incredulity” to my ear comes from the side that credulously believes that it must be possible.

That to me is the incredulity, the belief that because you cannot think of a barrier it must not exist. What are possible barriers ? They could fill up pages. That it takes longer than we have before as a civilization are otherwise destroyed, either by an asteroid crash, or by war using weapons of mass destruction, or by our destroying our climate. Or that the technology to do such is never deemed worth doing. Or is not possible despite the credulous belief that it must be, march of progress and all that …. Or that a culture that is able to get past the self-destruction potential filters is one that has also “gotten past” a drive to expand and grow for the sake of growth, instead getting to a point that focuses on a population sustainable within the means now available to them in their home system, while every expansive culture is doomed by their nature to destroy themselves first … Disease always hits first. Skipping many, lastly, who knows? For reasons we cannot imagine, despite your incredulousness that such a reason might exist.

Actually we don’t even know that.

We know that if they have it either hasn’t reached us yet, or we haven’t developed the means to detect it yet, or we missed it.

Not if there have been five hundred and the “lucky” roll hasn’t come up yet.

Nah. Many species, even the other fairly intelligent species of this planet, exist within their specialist niches just fine, adapting when forced out by changed events only. To the best of my knowledge we are the only species that makes a conscious effort expand to other niches.

I mean to imply no such thing. I’m on the no idea side. There may be none. There may be many. Given that we barely even have a good estimate of what the number of planets are that might be able to develop life, everything else is a guess. Maybe many exist at our level or a bit beyond but not to a point we have been able to observe. That cannot be ruled out. Maybe they have but do not want to be seen. Maybe those that want to be seen get snuffed out in the Dark Forest way. Lots of hypotheses possible and no way to rule them out.

290

I do not believe we can even say that as we do not know the nature of the Swiss cheese slices in front of us. They may be insurmountable or so rarely surmountable that non have yet done do.

291

It is, of course, merely supposition. But my gut feeling is that the odds of winning the Drake Equation (i.e. finding communicative extraterrestrial civilizations in the Milky Way Galaxy) is just a bit higher than winning the Mega Millions Lottery— 302,575,350 to 1. Somebody’s gonna win, but not many.

292

Certainly we can assume that civilisations may fall, for a variety of reasons; but we can’t assume that they will always fall. Nor can we assume that they will retain the same characteristics throughout their history; a civilisation which lasts for millions of years may not be expansive today, but it might be expansive a million years from now.

293

Exactly, well put.

I’m not claiming to know that ETIs are not very common e.g. the 1 per 1000ly example upthread, which would mean millions of ETIs in our galaxy alone.
I’m just suggesting that the proposition that they are common requires none of those species to have the ability or desire to make SR-probes, alongside many other technologies that would be visible to us (and alongside infinite other things that would be visible to us even if we didn’t know their purpose, like a disco ball megastructure).

The need to make blanket claims about either alien psychology or the limits of technology are reasons to disfavor such a proposition at this time.

Yes, if I had to put my money on one option at this time, I’d say this one. Maybe 3.5 billion years for multicellular life is unusually quick.

The L of the drake equation has been addressed, the point being that in fact, no, their civilization does not need to be alive within our light cone. Megastructures can exist indefinitely. Various noisy beacons can be noisy for billions of years; there’s no shortage of energy.
And part of the SR-probe concept is that replication also involves a fresh “tank of fuel” for the next probe (obviously speaking figuratively, there are many possible means of power / propulsion), so there is no known physics that would stop them before mega deep time (and they only need mere millions of years, maybe even less than 1 million years, to seed the whole galaxy).

294

Perhaps they could, but only if they were designed expressly to do so. Most large scale structures that I can imagine are dynamically unstable, and would gradually collapse into a debris disk a few million years after their station-keeping mechanisms cease to work.

We would probably see them as unusual dust clouds around mature stars - something else to look out for, I suppose.

295

Another way of putting that is that the one and only intelligent species that we know of, has attempted to broadcast its existence to the galaxy at the first moment of being able to do so.
Immediately making it seem implausible that thousands or millions of species will never attempt to do the same, and that at least some of them will not have superior tech.

Again: the list of things alien species could do that could be detectable is infinite. I don’t claim to have enumerated them all. Megastructures like Dyson swarms are just one example of one thing that has an apparent benefit (thus refuting the possible argument "there is no benefit to making a megastructure).

Pretty clear false dilemma there.
They don’t need to be “immortal” or “exist forever”. They just need to get a few centuries ahead of 2022 Homo sapiens’ level of tech. And, being as we’re pretty aggressive compared to most primates and other, non-primate intelligence on this planet, I would be very surprised if we represent the furthest point a civilization can reach.

296

I see no reason to suppose that, and “space station” is just one potential megastructure among an infinity of possible uses.
Plus the one example you gave you just self-refuted. :slight_smile:

297

Please elaborate.

298

You just conceded that we may be able to detect that kind of megastructure even if it had broken down into a cloud of dust. Which I don’t agree would necessarily happen, but the point is, even if it had, you speculate that it would still be detectable.

299

Yes, I think I agree with that. The debris disk would eventually coalesce into a number of planet-like objects, but the system would look detectably strange for hundreds of millions of years. I still can’t imagine a megastructure that would not collapse, however.

300

Nor can we assume they won’t. Or assume that any are interested in building a megastructure that outlasts them. Could be. Could be not.

Really no it doesn’t. (And here we go into the pissing match that gets old fast.)

There are lots of other potential explanations in a “many” ETA assumption.

They had and we missed it.

They have but our technology doesn’t notice it for a variety of possible reasons. Hasn’t reached us yet, too alien of a form of life, too different of a technology for us to read, so on. Perceive time itself differently than we do even. Who knows?

They have and were fairly quickly snuffed out by another more advanced ETI that is willfully dark, rationally scared of others being future threats and therefore quickly snuffing out potential competitors before they reach a possible threat stage. (“The Dark Forest” hypothesis.) Leaving only dark advanced ETIs left. Either exclusively hiding or predatorily dark hunters in the kill before killed mindset.

They had but destroyed themselves back to their equal of the Stone Age quickly as greater technology increases the chance to destroy your civilization in conflict or by accident.

Ones we cannot think of.