What do you think is the most likely explanation for the Fermi paradox?

[Grant Hatch]

I believe it makes at least as much sense to look for evidence of ET intelligence close to home vs distant, ie in our solar system as the solar system has existed for only approx 1/3 the accepted age of our galaxy. Quite possibly ET probes are in system watching us now given that Earth has been "habitable" for several billion years. This gives rise to the possibility that we can discover these probes if they are in long term low energy input, close (observational) orbits passing/close to Earth. At least gives us somewhere to look..... Such probes may have arrived thousands/millions/billions? of years ago and could conceivably be a source of paradigm shifting technology for us if capturable and brought to Earth.

[swampyankee]

I think there are a number of answers to the Fermi paradox, starting with what I consider most likely: that the assumptions resulting in the entire galaxy being full of alien civilizations within a few million years are based on excessive rates of growth. The other possibilities include interstellar travel being completely impractical, that rare astronomical events, such as GRB 080916C, "reset" civilizations, we are actually the technological leaders*, and many others, including some based on alien behavior (they're hiding, we're in some sort of wilderness preserve, etc).

In any case, even if there were traveling aliens in our stellar neighborhood, we've only had a significant chance of detecting them for a couple of centuries, and that would have only been by sheer luck. The local alien wave may have passed by before Homo sapiens or even tiktallik, let alone radio telescopes.

I think the most likely way to find alien civilizations is spectroscopic examination of planets, searching for likely technology indicators (and, no, I don't know what would unambiguously indicate technology short of a collimated, modulated signal directed towards Earth, although a planet emitting significant RF would be quite intriguing....)

-----

* John W Campbell would be pleased were that to be true.

[Colin Robinson]

Indubitably, Climate Change will be extremely expensive. It will require huge and likely unheard of quantities of energy resources to have a chance of taking control of our predicament.

I'd suggest that holding back climate change will take much greater discipline in how we use energy.

No matter how clean new energy sources become, total power dissipated will gradually increase global temperature and we'll have to deal with that within 100 years or so. ETI behaviour may sidestep greenhouse gases but will still have to face the same existential planetary thermodynamics issues facing all technological civilizations.

Perhaps the technological civilisations that survive longest are those which keep their ecosystems stable by restraining their energy consumption and production of waste. They do change their environment (every living species does) but the changes they bring about are small and subtle, hence difficult to detect at interstellar distances.

If they've detected us, they've probably detected that we're in boom-bust mode, heading for a major pratfall.

So when the galactic tribunal judges us, we can say: "Oh yeah? Youse too!"

I agree with the point that we're likely not the first to have faced these challenges.

Maybe the galactic tribunal (if there is one) will treat us leniently for that reason.

But will their leniency save us from natural consequences of our actions?

[Colin Robinson]

I think there are a number of answers to the Fermi paradox, starting with what I consider most likely: that the assumptions resulting in the entire galaxy being full of alien civilizations within a few million years are based on excessive rates of growth. The other possibilities include interstellar travel being completely impractical, that rare astronomical events, such as GRB 080916C, "reset" civilizations, we are actually the technological leaders*

* John W Campbell would be pleased were that to be true.

Or maybe we're among the technological also-rans, fouling our own planetary nest in a way that only a few technological species (the real leaders) are smart enough to avoid...

[Noclevername]

Moreover, if Brin's point is accepted, is it not a simple and plausible explanation for the so-called "eerie silence" — the fact that we haven't detected ETIs altruistically beaconing out free information to us humans?

Well, so do a great many other possible, simpler explanations.

But if there's plentiful intelligence out there, it is not a universal given that they would all think that way; some of them might disagree with Brin. Indeed, our species did and do continue to attempt METI.

We talk to our dogs, even, and teach apes sign language. We have some degree of inter-species altruism, like setting up bird feeders. We generally don't like to see an animal suffer unnecessarily, and consider it cruel to mistreat one.

[Colin Robinson]

Well, so do a great many other possible, simpler explanations.

But if there's plentiful intelligence out there, it is not a universal given that they would all think that way; some of them might disagree with Brin. Indeed, our species did and do continue to attempt METI.

We talk to our dogs, even,

Well, dogs and humans are something of a special case, because the two species have co-evolved for thousands of years.

When and if we make contact with highly advanced ETIs, it's possible we'll be treated like dogs... but only if we're lucky.

and teach apes sign language. We have some degree of inter-species altruism, like setting up bird feeders. We generally don't like to see an animal suffer unnecessarily, and consider it cruel to mistreat one.

Actually Brin's article acknowledges examples of inter-species altruism.

The question he raises, is whether or not inter-species altruism is likely to be prevalent enough to determine what happens in terms of interstellar messaging.

[Noclevername]

Maybe possibly perhaps it's conceivable that multiple civilizations exist but there are explanations based on alien behavior, rather than technical or physical difficulties or simple absence. But the point of the Fermi exercise is not to determine the vastness of our own imaginations and stretching the limits of the possible by asking "what if" (though I do enjoy a good what-if story as entertainment). The purpose is to figure out what's most likely to be true. We cannot rule out behavioral reasons for silence but the fact is that hard physical limits do exist, and are sufficient by themselves to hobble the basic Fermi premise of universal expansion of interstellar spacefaring civilizations.

ETI would have to overcome these massive challenges and energy costs over and over again at every new star in addition to finding us and putting us aside, or what have you. The Zoo hypothesis for instance, only makes sense at all if interstellar travel and communication are easy, cheap, and plentiful, otherwise why bother to ban the already almost unachievable?

[Noclevername]

Well, dogs and humans are something of a special case, because the two species have co-evolved for thousands of years.

Because we fed them. That's how and why they are domesticated to begin with.

Actually Brin's article acknowledges examples of inter-species altruism.

The question he raises, is whether or not inter-species altruism is likely to be prevalent enough to determine what happens in terms of interstellar messaging.

It seems we already have our answer, having tried to do so multiple times as a species.

[Colin Robinson]

Because we fed them. That's how and why they are domesticated to begin with.

We fed them meat, which they helped us get hold of via hunting.

Historically, domestication of the dog has been an instance of what Brin calls "pragmatic cooperation" rather than altruism.

It seems we already have our answer, having tried to do so multiple times as a species.

Our attempts at METI have been intermittent and controversial.

I know you think they'll increase in the future, but I'm not convinced it will happen.

[Noclevername]

Our attempts at METI have been intermittent and controversial.

And still we tried, despite the costs and resistance. What does that say about our need to seek other intelligences? Seems to be a non-trivial driving force, part and parcel of the curiosity that drove us to space.

[Colin Robinson]

And still we tried, despite the costs and resistance.

We as a species, over our history, have put a lot more time and effort into building pyramids...

Does it follow that future humans will also build pyramids, or that extraterrestrials (if they exist) build pyramids too?

What does that say about our need to seek other intelligences? Seems to be a non-trivial driving force, part and parcel of the curiosity that drove us to space.

Curiosity is undoubtedly an important human motive... But how likely are we to satisfy our curiosity either by listening for deliberately-sent radio messages from other worlds, or by sending out our own messages to them?

Radio communication is for us a comparative novelty, in the sense that we've had it for a very small fraction of our existence as a species.

It has undoubtedly done a lot to build bridges between continents and countries, to create what Marshall McLuhan called "the Global Village".

Some have speculated that radio communication could also build bridges between planets, and create what Ronald N. Bracewell called "the Galactic Club".

The SETI Institute and the METI Institute have worked hard to test this speculation, but they haven't proved yet it to be true.

Would you agree that future humans may or may not share our current enthusiasm for radio communication?

And that ETIs, if they exist, also may or may not share that enthusiasm?

[Noclevername]

We as a species, over our history, have put a lot more time and effort into building pyramids...

Does it follow that future humans will also build pyramids, or that extraterrestrials (if they exist) build pyramids too?

You're still missing the point. It's about "yes we did" or "no we didn't", it's not about relative effort compared to other endeavors. It's a question of the existence of METI as a goal. We seek to make contact, period, despite objections like yours made every time the effort is made. It's still considered worthwhile by a portion of our species even if another portion disagrees. So the drive for contact exists. It's not something anyone can argue doesn't exist or never happens.

Curiosity is undoubtedly an important human motive... But how likely are we to satisfy our curiosity either by listening for deliberately-sent radio messages from other worlds, or by sending out our own messages to them?

We do. We are. "How likely" is an unanswerable question.

Radio communication is for us a comparative novelty, in the sense that we've had it for a very small fraction of our existence as a species.

It has undoubtedly done a lot to build bridges between continents and countries, to create what Marshall McLuhan called "the Global Village".

Some have speculated that radio communication could also build bridges between planets, and create what Ronald N. Bracewell called "the Galactic Club".

The SETI Institute and the METI Institute have worked hard to test this speculation, but they haven't proved yet it to be true.

Well, as you say, we've barely begun trying, so you answered your own question... it's far too soon to know. That's why we have science: for the unanswered questions.

Would you agree that future humans may or may not share our current enthusiasm for radio communication?

And that ETIs, if they exist, also may or may not share that enthusiasm?

As far as alien motivations I can't say. TBD. As for humans, no, I don't believe RF communication is a passing fad. It's here to stay, as its properties make it useful for that purpose.

It's like water-based organic life; we already know it happens so it can be said self-evidently to be a reasonable basis for life. We can look for other solvents and compounds but they are purely speculative. Same with RF, it proves useful enough to be the basis for the overwhelming majority of telecommunication. Those properties are universal, so we might reasonably expect that a civilization that has enough industrial technology to go into space or search the skies for life would also put RF to use.

[Colin Robinson]

You're still missing the point. It's about "yes we did" or "no we didn't", it's not about relative effort compared to other endeavors. It's a question of the existence of METI as a goal. We seek to make contact, period, despite objections like yours made every time the effort is made. It's still considered worthwhile by a portion of our species even if another portion disagrees. So the drive for contact exists. It's not something anyone can argue doesn't exist or never happens.
We do. We are. "How likely" is an unanswerable question.
Well, as you say, we've barely begun trying, so you answered your own question... it's far too soon to know. That's why we have science: for the unanswered questions.

It's true that science seeks answers to unanswered questions.

But aren't there different kinds of questions? For instance, highly specific questions, and more general, open questions.

Whether there are radio transmitters on other planets is a highly specific question. It is actually a lot more specific than asking whether there is intelligence on other planets.

As far as alien motivations I can't say. TBD. As for humans, no, I don't believe RF communication is a passing fad. It's here to stay, as its properties make it useful for that purpose.

It's been useful for some purposes, e.g. sending messages to people in another country who not only have similar technology to the broadcasters, but also understand a language the broadcasters can speak in.

Its usefulness for communication between different species on different planets has been speculated but not proven.

Those properties are universal, so we might reasonably expect that a civilization that has enough industrial technology to go into space or search the skies for life would also put RF to use.

You're saying that if they resemble us in terms of having cities and factories and rockets and telescopes then they'll likely have radio into the bargain...

Maybe so...

But intelligent life may not resemble us in any of those ways.

Consider the history of human intelligence, here on Earth, as we know it. The history of human intelligence goes back about 100 thousand years — and that includes only AMHs, anatomically modern humans, and not their close relatives such as Neanderthals.

When you talk about "a civilisation that has enough industrial technology to go into space" etc, you're talking about technologically modern humans -- TMHs, they might be called. These TMHs have only existed for a century or two, and their long-term prospects are far from clear...

[Noclevername]

It's true that science seeks answers to unanswered questions.

But aren't there different kinds of questions? For instance, highly specific questions, and more general, open questions.

Whether there are radio transmitters on other planets is a highly specific question. It is actually a lot more specific than asking whether there is intelligence on other planets.



It's been useful for some purposes, e.g. sending messages to people in another country who not only have similar technology to the broadcasters, but also understand a language the broadcasters can speak in.

Its usefulness for communication between different species on different planets has been speculated but not proven.



You're saying that if they resemble us in terms of having cities and factories and rockets and telescopes then they'll likely have radio into the bargain...

Maybe so...

But my point is that intelligent life wouldn't necessarily resemble us in any of those ways.

Consider the history of human intelligence, here on Earth, as we know it. The history of human intelligence goes back about 100 thousand years — and that includes only AMHs, anatomically modern humans, and not their close relatives such as Neanderthals.

When you talk about "a civilisation that enough industrial technology to go into space" etc, you're talking about technologically modern humans -- TMHs, they might be called. These TMHs have only existed for a century or two, and their long-term prospects are far from clear...

But the point is, we have a way to detect intelligence that we already know exists and works, and is reasonable to expect from a spacefaring society. So sending radio messages is a reasonable way to communicate.

As far as whether or not it's existentially safe, we do a lot more self-destructive and dangerous things all by our lonesome. I doubt potential danger will be a deterrent.

[Colin Robinson]

But the point is, we have a way to detect intelligence that we already know exists and works, and is reasonable to expect from a spacefaring society.

So sending radio messages is a reasonable way to communicate.

As far as whether or not it's existentially safe, we do a lot more self-destructive and dangerous things all by our lonesome. I doubt potential danger will be a deterrent.

How long do you think groups of humans will keep sending out messages, if we don't detect any messages from others?

Decades? Centuries? Geological time?

[Noclevername]

How long do you think groups of humans will keep sending out messages, if we don't detect any messages from others?

Decades? Centuries? Geological time?

As long as we're human. It's in our nature to reach out.

[Jens]

In response to this:

How long do you think groups of humans will keep sending out messages, if we don't detect any messages from others?

Was this response.

As long as we're human. It's in our nature to reach out.

I would have a different response, personally.

I don't really understand how you can make such a generalization. I think you're arguing that we have a need to reach out to aliens (that we don't even know to exist...) as a extension of our social nature. But sorry, I don't feel that at all. I guess that you may feel that need, and assume that it is universal, and perhaps Colin doesn't feel it as well, and so is skeptical. I don't really feel a need to reach out even to other human beings that I don't know exist, so I don't know why I would feel compelled to reach out to aliens who, again, I don't even know to exist...

My response would be a bit different then. I would rather say that... Or rather, I would start with a sort of observation. In science fiction it seems to be often given that people of the same species all speak the same language, like Klingon or whatever, and have the same motivations. But in fact, as a "human race" we don't really have a unified position on many things, including this one. And there are no regulations about it, so among the four billion people on our planet there are people interested in finding out about whether aliens exist and who are not afraid to make broadcasts, and since there are no regulations against it, they will continue. So my answer to Colin would probably be that there will be people who will continue to do it until some international consensus emerges that it is dangerous and should be forbidden (or that funding agencies come to that consensus and stop funding such efforts).

And if no consensus is made, I suspect that it will continue in some form because, as I said, there are a lot of people on earth, and certainly there will be a number who will be interested in that endeavor.

[Noclevername]

In response to this:



Was this response.



I would have a different response, personally.

I don't really understand how you can make such a generalization. I think you're arguing that we have a need to reach out to aliens (that we don't even know to exist...) as a extension of our social nature. But sorry, I don't feel that at all. I guess that you may feel that need, and assume that it is universal, and perhaps Colin doesn't feel it as well, and so is skeptical. I don't really feel a need to reach out even to other human beings that I don't know exist, so I don't know why I would feel compelled to reach out to aliens who, again, I don't even know to exist...

My response would be a bit different then. I would rather say that... Or rather, I would start with a sort of observation. In science fiction it seems to be often given that people of the same species all speak the same language, like Klingon or whatever, and have the same motivations. But in fact, as a "human race" we don't really have a unified position on many things, including this one. And there are no regulations about it, so among the four billion people on our planet there are people interested in finding out about whether aliens exist and who are not afraid to make broadcasts, and since there are no regulations against it, they will continue. So my answer to Colin would probably be that there will be people who will continue to do it until some international consensus emerges that it is dangerous and should be forbidden (or that funding agencies come to that consensus and stop funding such efforts).

And if no consensus is made, I suspect that it will continue in some form because, as I said, there are a lot of people on earth, and certainly there will be a number who will be interested in that endeavor.

I doubt humanity can come to such a consensus, given our fractious nature, but I suppose it's temporarily possible for a government or coalition of nations that bans such activity to hold power for a while.

However, on average humans reach outside our species. We always have. We establish relationships with things, we anthropomorphize and talk to animals and even inanimate objects, we imagine gods and monsters. We want there to be others. It's how our minds work; we seek patterns and relationships based on what we value or are familiar with. We want like minds so much that we create them in our minds where they don't exist.

I have said many times, we will leave the nest and expand into space unless we die as a species. We will some distant day have industrially and materially-independent space habitats all over the Solar System. In such a scenario, the kind of central control that could prevent METI would be impossible, as societies based light-hours apart can establish their own priorities. We would revert to type, in my opinion, in addition to having many opportunities to collect and use energy as we please. Certainly a civilization that can accomplish mature space settlement can spare the resources to punch out a coded radio beam at the stars every few years. There will undoubtedly be times when we aren't actively trying to make contact, but those gaps will not be permanent. There's just too many people who want to even if it's difficult. Eventually it'll stop being difficult to do so, as our technology and access to Solar resources and energy develop.

I do not and cannot know if any of this could carry over to an alien intelligence. There's nothing on which to base such a speculation beyond imagination. But with humans, I can say with confidence that some efforts at METI will continue for as long as we're physically capable.

[Colin Robinson]

I doubt humanity can come to such a consensus, given our fractious nature, but I suppose it's temporarily possible for a government or coalition of nations that bans such activity to hold power for a while.

However, on average humans reach outside our species. We always have. We establish relationships with things, we anthropomorphize and talk to animals and even inanimate objects, we imagine gods and monsters. We want there to be others. It's how our minds work; we seek patterns and relationships based on what we value or are familiar with. We want like minds so much that we create them in our minds where they don't exist.

I have said many times, we will leave the nest and expand into space unless we die as a species. We will some distant day have industrially and materially-independent space habitats all over the Solar System. In such a scenario, the kind of central control that could prevent METI would be impossible, as societies based light-hours apart can establish their own priorities. We would revert to type, in my opinion, in addition to having many opportunities to collect and use energy as we please. Certainly a civilization that can accomplish mature space settlement can spare the resources to punch out a coded radio beam at the stars every few years. There will undoubtedly be times when we aren't actively trying to make contact, but those gaps will not be permanent. There's just too many people who want to even if it's difficult. Eventually it'll stop being difficult to do so, as our technology and access to Solar resources and energy develop.

I do not and cannot know if any of this could carry over to an alien intelligence. There's nothing on which to base such a speculation beyond imagination. But with humans, I can say with confidence that some efforts at METI will continue for as long as we're physically capable.

What, in your opinion, is the most likely explanation for what Paul Davies calls "the eerie silence"?

[Noclevername]

What, in your opinion, is the most likely explanation for what Paul Davies calls "the eerie silence"?

The scale of the Universe. Even what's nearby is very far away.

If there's any intelligence out there it's not within our range of detection.

[7cscb]

Wait a second. What's the difference between Eerie Silence and the Fermi paradox?

[Colin Robinson]

I don't really understand how you can make such a generalization. I think you're arguing that we have a need to reach out to aliens (that we don't even know to exist...) as a extension of our social nature. But sorry, I don't feel that at all. I guess that you may feel that need, and assume that it is universal, and perhaps Colin doesn't feel it as well, and so is skeptical.

One of the things I'm skeptical of, is whether species that evolve on different planets are likely to be understand messages they might beam out to each other.

I'm sceptical of the argument that shared principles of maths, science, and engineering would enable that to happen.

Even if they are (so to speak) mapping the same territory we are, does that mean we'll be able to read their maps, or vice versa?

Could they be as intelligent as humans without being intelligible to humans, and without humans being intelligible to them?

[Colin Robinson]

Wait a second. What's the difference between Eerie Silence and the Fermi paradox?

The phrase "Eerie Silence" refers to part of the Fermi Paradox. The Fermi Paradox is about why we don't observe a range of things that would be unmistakeable evidence of intelligent extraterrestrial life, including ET spacecraft and colonists on Earth; as well as why we haven't yet picked up ET radio transmissions.

[Noclevername]

One of the things I'm skeptical of, is whether species that evolve on different planets are likely to be understand messages they might beam out to each other.

I'm sceptical of the argument that shared principles of maths, science, and engineering would enable that to happen.

Even if they are (so to speak) mapping the same territory we are, does that mean we'll be able to read their maps, or vice versa?

Could they be as intelligent as humans without being intelligible to humans, and without humans being intelligible to them?

No way to know except to find it, which may or may not happen. But if we and they are sending out deliberate signals meant to be understood, we're going to try to make our messages as broadly clear as we can come up with. Some things are literally Universal; we'll try (we may not succeed) to make the best use of recognizable physical constants and properties.

[Jens]

One of the things I'm skeptical of, is whether species that evolve on different planets are likely to be understand messages they might beam out to each other.

I'm sceptical of the argument that shared principles of maths, science, and engineering would enable that to happen.

Even if they are (so to speak) mapping the same territory we are, does that mean we'll be able to read their maps, or vice versa?

Could they be as intelligent as humans without being intelligible to humans, and without humans being intelligible to them?

I guess it's possible. What I think is a bit problematic is that we look for signals that are "unnatural." But the problem is that there have been times when we detected something that seemed unnatural at the time, but then later was discovered to actually be the sign of a natural phenomenon. So it's kind of difficult to be able to make a clear judgment that something is unequivocally artificial.

[Noclevername]

I guess it's possible. What I think is a bit problematic is that we look for signals that are "unnatural." But the problem is that there have been times when we detected something that seemed unnatural at the time, but then later was discovered to actually be the sign of a natural phenomenon. So it's kind of difficult to be able to make a clear judgment that something is unequivocally artificial.

I think that's kind of seeing it as, "Well all the giants we charged at have actually been windmills, therefore giants are nearly indistinguishable from windmills." But if we haven't seen an actual giant so far, we don't know if they look anything like windmills at all. They could be completely distinct, not matching our mental image of a giant.

[Jens]

I think that's kind of seeing it as, "Well all the giants we charged at have actually been windmills, therefore giants are nearly indistinguishable from windmills." But if we haven't seen an actual giant so far, we don't know if they look anything like windmills at all. They could be completely distinct, not matching our mental image of a giant.

As usual, you are completely misinterpreting me.

I am only talking about the difficulty of interpretation. I completely agree that they could be completely different, not matching our mental image.

[Noclevername]

As usual, you are completely misinterpreting me.

I am only talking about the difficulty of interpretation. I completely agree that they could be completely different, not matching our mental image.

Well, without an example we don't know what the difficulty level of interpretation is.

[cosmocrazy]

I guess it's possible. What I think is a bit problematic is that we look for signals that are "unnatural." But the problem is that there have been times when we detected something that seemed unnatural at the time, but then later was discovered to actually be the sign of a natural phenomenon. So it's kind of difficult to be able to make a clear judgment that something is unequivocally artificial.

Absolutely, we don't know for certain what we are looking for and could well be missing communication staring us right in our face. I guess we can only assume based on what we know and therefore lookout for patterns that appear to be either complex or very random. These may indicate an "unnatural" source possibly even intelligence. Unless we discover a more efficient way of long distance communication then we can only assume that ET would use the same methods as us. What else can we do?

I guess it could be a bit like someone looking for smoke signals or listening for the beating of loud drums cause that's the only way they know how to send messages long distances, not realising that the air is filled with radio signals all around them. They would likely conclude that there is no one out there just an "eerie" silence.

[Jens]

Well, without an example we don't know what the difficulty level of interpretation is.

Whatever.