The Fermi Paradox ...life in the galaxy explained

[Daehawk]

And explained the best Ive EVER seen. An amazing read for sure.

http://waitbutwhy.com/2014/05/fermi-paradox.html

[YellowKing]

Wow, that was an awesome read. While I was familiar with many of the concepts, I had never seen them laid out so so succinctly.

[msteelers]

Agreed. I enjoyed that. Thanks for posting it.

[Jaymann]

The Great Filter may just be The Technological Singularity.

[stessier]

While there, check out Putting Time in Perspective. I especially like the ending few timelines that show the Future and The Past.

[Lassr]

that is one of the better summaries of the topic I have ever read. Thanks!

[Paingod]

The Great Filter may just be The Technological Singularity.

Makes me wonder how many planets might be run by machines, or got turned into balls of nano-goo by some unwitting scientist.

[El Guapo]

Excellent post. I'm kind of rooting for one of my kids to go into astrophysics or astronomy or what have you, because it's all just so mind-blowing.

[wonderpug]

The Great Filter may just be The Technological Singularity.

Makes me wonder how many planets might be run by machines, or got turned into balls of nano-goo by some unwitting scientist.

14

[Doomboy]

The Great Filter may just be The Technological Singularity.

Makes me wonder how many planets might be run by machines, or got turned into balls of nano-goo by some unwitting scientist.

14

I thought it was only 13. Or did the Nebulons invent Happy Fun Ball and taunt it?

[Unagi]

The Great Filter may just be The Technological Singularity.

Makes me wonder how many planets might be run by machines, or got turned into balls of nano-goo by some unwitting scientist.

14

I thought it was only 13. Or did the Nebulons invent Happy Fun Ball and taunt it?

It's 13, unless you count the mongo-goo planet of Blungo-7, and no serious nano-goo-ologist does.

/sneers at Wonderpug

[El Guapo]

The Great Filter may just be The Technological Singularity.

Makes me wonder how many planets might be run by machines, or got turned into balls of nano-goo by some unwitting scientist.

14

I thought it was only 13. Or did the Nebulons invent Happy Fun Ball and taunt it?

It's 13, unless you count the mongo-goo planet of Blungo-7, and no serious nano-goo-ologist does.

/sneers at Wonderpug

Maybe GreenGoo could help figure this out.

[The Meal]

Arise!

For folks interested in the history of these sorts of things, this was a nice article as to how this all came about, and why "Fermi's Paradox" is a misnomer.

[Jaymann]

While it neither Fermi's nor a paradox, the conundrum, if you will, certainly exists. In some respects it falls into the "we don't know what we don't know" category. One thing I find fascinating is it could be resolved nearly instantaneously (say, by alien contact) or not resolved at all throughout the course of human existence.

[gameoverman]

That question, where is everybody, does not make sense if you think about how short a time we've been looking. On some level that perspective is self serving, meant to support the idea that humans are somehow important or special. Vast alien empires could come and go and we'd never know it, either because it happened too long ago/too far away/too far into the future/all of the previous reasons. We aren't the hub of all that is known.

One idea I like is the Great Filter. That's because if an intelligence keeps advancing, one predictable result will be their eventual development of a tech or weapon capable of destroying their own existence. How long did we have the atom bomb before we used it on someone? How long before we develop something, it doesn't even have to be a weapon, so powerful that even testing it results in cataclysmic consequences that were unforeseeable due to the complexity of the technology?

[BooTx]

That question, where is everybody, does not make sense if you think about how short a time we've been looking. On some level that perspective is self serving, meant to support the idea that humans are somehow important or special. Vast alien empires could come and go and we'd never know it, either because it happened too long ago/too far away/too far into the future/all of the previous reasons. We aren't the hub of all that is known.

Well the whole point of the paradox is that regardless of how little time we've spent looking; signs of extraterrestrial life should still be evident simply because of the timescales involved. If habitable planets are even remotely common, there should be billions of them, each with potentially billions of years of habitability behind them. If humans (complex, intelligent life) aren't "important or special" then there should be billions of civilizations in the Universe.

Now, if you look at how quickly humanity has advanced in just the last hundred years or so, and imagine a civilization that's a million years (a trifle) more advanced than us, it's extremely hard to believe that they wouldn't have made serious progress towards interstellar travel. And then it would theoretically only take, what, 50 million years to colonize the entire galaxy at 10% light speed?

50 million years is nothing on the cosmic timescale. And that's one civilization. Out of potentially millions, or even billions.

And I know you might say well maybe that civilization isn't like humanity; maybe they wouldn't choose to spread so prolifically. And you know that may very well be true, but the thing of it is this: It only takes one, and you can't tell me that out of those countless potential civilizations they're all just sitting quietly in their home systems.

And sure, some of those species may have chosen to hide themselves from us. Maybe even most of them. Maybe even the vast majority of them. But all of them? I do find that to be very hard to believe.

Maybe a lot of them destroyed their own civilization inadvertently once they reached some sort of point in their evolution. Maybe even most of them. But all of them? I wonder.

And what I think is probably the most puzzling aspect of all which is the robotics and artificial intelligence angle. We're already developing interplanetary robots and we just started playing this game. Common sense would tell you that other civilizations would have come up with the same idea and utilized it exponentially more so than us. Common sense would also tell you that they would be able to detect that our little Earth is a habitable planet worth looking into. If there are millions of civilizations around the Milky Way with potentially millions of years of advancement behind them, why is our blue marble not littered with various Spirits and Opportunities?

I'm not saying there's not extraterrestrial life out there any more than I'm saying there is, but I think the question is certainly valid and open to debate.

[gameoverman]

Using the anthill analogy from the article, if you have a picnic near an anthill, you might expect at least a few of those ants to discover your picnic and start swarming over your sandwich. However, this is dependent on a lot of factors, including how long the picnic lasts. how far the ants are from you, and whether or not the ants are already scouting in your area. Anything is possible from the ants being aware of you from the moment you arrive, to you showing up and having your picnic and then leaving and the ants never even knew you were there.

The Fermi Paradox question, as I understand it, takes it as a given that if there's a picnic then the ants will find it. If the ants look and look but find no picnic it's because there are no picnickers. If there is intelligent life then we will detect it, which is what I disagree with. That's a huge assumption based on no sound reasoning. Even if the galaxy was colonized we might not see anything, since who knows what advanced intelligence colonies might look like, or even if they'd 'look' like anything at all?

[Kraken]

If there is intelligent life then we will detect it, which is what I disagree with. That's a huge assumption based on no sound reasoning. Even if the galaxy was colonized we might not see anything, since who knows what advanced intelligence colonies might look like, or even if they'd 'look' like anything at all?

Yeah, this.

We only have one example to generalize from -- ourselves. We think that life leads to sentience leads to civilization leads to technology and technology would look something like ours because the beings that develop it will have the same needs that we do. So we conclude that aliens like us are rare to nonexistent -- which might be true, but it's based on a long chain of Ifs. Maybe intelligent beings that aren't like us at all are common and we have no idea what to look for, if they're detectable at all.

Even our own example is just a brief moment in time. We think that aliens ought be leak detectable electromagnetic signals because we do, but we're already replacing radio broadcasts with lasers and microwaves. The era when we spewed radio waves in every direction is already looking like it was just a blip.

The only thing the Fermi paradox tells us is that people like us are rare to nonexistent. Maybe. And I can easily believe that even with billions of habitable worlds, the human path is unique.

[Blackhawk]

Turn it around.

If there is alien life out there, intelligent life, how much of it is likely to have detected us?

Keep in mind that we were essentially undetectable until a century ago. Meeting 19th century-equivalent beings would certainly fit the 'intelligent alien life' requirement, yet they wouldn't be detectable unless we were sitting in their laps.

[dbt1949]

I think aliens have contacted and visited us. How else do you explain Prince?

[Daehawk]

Surely a galactic ship would have very sensitive sensors on it. If they were close around the time of WW2 and all the nuke testing they should have seen us.

[Paingod]

Keep in mind that we were essentially undetectable until a century ago. Meeting 19th century-equivalent beings would certainly fit the 'intelligent alien life' requirement, yet they wouldn't be detectable unless we were sitting in their laps.

Star Trek Voyager covered that once. They bumped into a bunch of humans that had been abducted by aliens and moved across the galaxy - but weren't detecting their initial signals because they don't monitor 'unadvanced' communications channels. FM Radio just wasn't something they bothered to tune in.

Not to mention, the galaxy is a big place. We could have been surveyed 100,000 years ago and simply logged as a habitable life-infested planet. There'd be little point in coming back over and over once they registered the mineral contents of the world and moved on.

[msduncan]

This is a great read. One comment:

1) if the great filter were ahead of us rather than behind, wouldn't we be detecting noise from civilizations that also had not yet reached the great filter? If the great filter occurs after where we are right now, then other civilizations would have also reached the capability to start broadcasting noise... and it would be a lot of noise from all sorts of directions assuming there are tons of civilizations that were much more ancient prior to the filter wiping most of them out.

[Grifman]

That question, where is everybody, does not make sense if you think about how short a time we've been looking.

It has nothing to do with how long we've been looking but everything to do with how long other civilizations should have existed. Given that ours is a young star, there should have been many civilizations that have arisen.

On some level that perspective is self serving, meant to support the idea that humans are somehow important or special.

I could just as easily say that your position is self serving because you want to not make humans special. See how easy that is? Point is, I don't get the sense that most professionals involved in this discussion care much one way or another. In fact most probably leans towards the idea that humans aren't special.

Vast alien empires could come and go and we'd never know it, either because it happened too long ago/too far away/too far into the future/all of the previous reasons. We aren't the hub of all that is known.

Again, you miss that point that given the young age of our star, there should have been many powerful civilizations that would have arisen before us, and they should have left obvious signs of their existence.

[One idea I like is the Great Filter. That's because if an intelligence keeps advancing, one predictable result will be their eventual development of a tech or weapon capable of destroying their own existence. How long did we have the atom bomb before we used it on someone? How long before we develop something, it doesn't even have to be a weapon, so powerful that even testing it results in cataclysmic consequences that were unforeseeable due to the complexity of the technology?

The problem with the Great Filter is that it seems improbable that every civilization falls prey to it. Given the large number of civilizations that should have arisen, surely some of them didn't succumb. It just seems unlikely that this happens to every civilization.

[TiLT]

Surely a galactic ship would have very sensitive sensors on it. If they were close around the time of WW2 and all the nuke testing they should have seen us.

There's a lot of assumptions involved in what you're saying. If they have a galactic ship, if that ship has very sensitive sensors, if those sensors can detect nuclear tests, if the ship is at the exact distance and at the exact time when the data their sensor might pick up is actually there to pick up in the first place, if the ship is even using the sensors to begin with, if "seeing" even means anything to this species we're talking about, and so on. If all of those things were true, then maybe they'd see us. Maybe. Events from WW2 are currently potentially observable at a distance of 70-75 light years (no more and no less) away from Earth, and would be very, very faint and scattered. If an alien species were to pass within 70-75 light years of Earth right now, they might see us. Again, might.

Thanks for posting that link last year btw. I missed it at the time, and it's a great read.

[TiLT]

This is a great read. One comment:

1) if the great filter were ahead of us rather than behind, wouldn't we be detecting noise from civilizations that also had not yet reached the great filter? If the great filter occurs after where we are right now, then other civilizations would have also reached the capability to start broadcasting noise... and it would be a lot of noise from all sorts of directions assuming there are tons of civilizations that were much more ancient prior to the filter wiping most of them out.

What noise would that be? The popular belief is that Earth's radio signals are steadily traveling into space to be heard by other potential species out there, but the truth is that those signals are so weak and intermittent that they are likely almost impossible to hear by now, if possible at all. Those very first radio signals are right now only around 100 light years away from Earth, an incredibly short distance on a galactic scale.

You're also assuming that any "audible" noise produced by an advanced civilization is similar to the noise produced by a different civilization. We might be the only species in the universe to use radio signals, and other species might never look for ours. On the flip side, Earth might be bombarded with alien noise daily, but we're simply incapable of recognizing it for what it is.

Even if there are 1000 civilizations out there in the Milky Way right now with a tech-level similar to ours, the distances between our civilizations would still, statistically speaking, be immense.

[Grifman]

Even if there are 1000 civilizations out there in the Milky Way right now with a tech-level similar to ours, the distances between our civilizations would still, statistically speaking, be immense.

The point of the Fermi paradox isn't that there are a 1000 civilizations out there with a tech level similar to ours but due to the age of our star compared with the age of our galaxy that there should be thousands far more advanced than ours, and their existence should be overwhelmingly obvious.

[TiLT]

Even if there are 1000 civilizations out there in the Milky Way right now with a tech-level similar to ours, the distances between our civilizations would still, statistically speaking, be immense.

The point of the Fermi paradox isn't that there are a 1000 civilizations out there with a tech level similar to ours but due to the age of our star compared with the age of our galaxy that there should be thousands far more advanced than ours, and their existence should be overwhelmingly obvious.

Yes, but the post I replied to had the assumption (if I read it right) that the Great Filter is just ahead of ourselves, thus ruling out such advanced civilizations. Of course, msduncan might have been talking about very advanced civilizations, in which case I misread the whole thing. In that case, the question is answered by the article in the OP.

[Blackhawk]

Events from WW2 are currently potentially observable at a distance of 70-75 light years (no more and no less) away from Earth, and would be very, very faint and scattered.

...and the visible burst of energy from the atomic tests would be seconds long, at best, and that's assuming that the sensors at that range could distinguish them from the huge nuclear reaction known as the sun.

[Grifman]

Even if there are 1000 civilizations out there in the Milky Way right now with a tech-level similar to ours, the distances between our civilizations would still, statistically speaking, be immense.

The point of the Fermi paradox isn't that there are a 1000 civilizations out there with a tech level similar to ours but due to the age of our star compared with the age of our galaxy that there should be thousands far more advanced than ours, and their existence should be overwhelmingly obvious.

Yes, but the post I replied to had the assumption (if I read it right) that the Great Filter is just ahead of ourselves, thus ruling out such advanced civilizations. Of course, msduncan might have been talking about very advanced civilizations, in which case I misread the whole thing. In that case, the question is answered by the article in the OP.

Sorry, my bad. It just seems a lot of people are ignoring this basic assumption of the Fermi paradox.

[msduncan]

I think my point or question is that since our star is relatively younger, I'm assuming that the many intelligent civilizations out there in our neighborhood would have, long ago, gone through periods of development where they produced chatter that could be heard. It's been long enough since our star is so young that the chatter should have been reaching us by now. So with those assumptions the filter would likely be behind us, right?

[El Guapo]

I'm not sure why we would assume that a civilization would eventually colonize substantially the whole galaxy given enough time. If the speed of light is a hard physics rule that can't be overcome with sufficiently advanced technology, that means it would take enormous amounts of time to colonize even relatively near worlds, to say nothing of worlds on the other side of the galaxy. It may well be possible for a civilization to do that over enough time (say by the self-replicating colonizers that the original article mentions), but what reason would a civilization have to do that? You would spend an enormous amount of resources building the colonizer, send it out...and then never hear anything from the colony at least until long after everyone alive at the time is dead and gone. You might not be able to communicate effectively with other colonized worlds, probably can't get resources back.

It might make sense to colonize a couple worlds just to avoid the risk that the entire species gets wiped out by some cataclysmic event impacting the original world, but why would we assume that they would decide to colonize the whole galaxy?

[El Guapo]

Also I agree with Hawking and Sagan that actively attempting to contact alien species is incredibly stupid and reckless.

[msduncan]

Also I agree with Hawking and Sagan that actively attempting to contact alien species is incredibly stupid and reckless.

Maybe the great filter is ahead of us, and it is some sort of aggressive resource consuming ancient species that hulk smashes civilizations when they pop their heads up.

[Blackhawk]

Also I agree with Hawking and Sagan that actively attempting to contact alien species is incredibly stupid and reckless.

Maybe the great filter is ahead of us, and it is some sort of aggressive resource consuming ancient species that hulk smashes civilizations when they pop their heads up.

Well, you managed to summarize all of Stargate: Atlantis in one sentence.

[noxiousdog]

Most of you are still thinking about this backwards. You don't assume that a civilization would want to colonize the galaxy; you don't assume a civilization could hide itself.

You have to assume that NONE of them have wanted to colonize the galaxy (it's easy even at sublight speeds) and that NONE of them have left any trace. No device sending out radio waves, no device that shows as artificial.

Think of how much we can detect and how far away it is.

Is it conclusive? Of course not. But I think it makes civilization and perhaps more importantly the ability to sustain civilization much, much harder than we appreciate.

[msduncan]

Could it be that dark matter or some other substance yet unknown blocks or filters out all but the strongest noise? High energy type stuff...... So in effect we are all in a shroud that makes it hard to hear except in exceptionally strong cases or close proximity (or extreme luck)?

[Isgrimnur]

Our star isn't young. The universe is ~14 billion years old., Our star is ~4.5 billion years old, with about the same to go. Out star has been around for over 1/3 of of the universe and is middle-aged.

[LawBeefaroni]

Could it be that dark matter or some other substance yet unknown blocks or filters out all but the strongest noise? High energy type stuff...... So in effect we are all in a shroud that makes it hard to hear except in exceptionally strong cases or close proximity (or extreme luck)?

Except we can see galaxies over 10 billion light years away. We can see cosmic microwave background radiation from right around the time of the big bang. I don't think the problem is a selective noise filter but rather a general one. That being distance. Distance, which is also time in this case.


Personally I think the same vastness of space that makes life inevitable, by mathematical calculation, also makes it very very far apart. Which makes life very very hard to detect, by the laws of physics.

[The Meal]

You have to assume that NONE of them have wanted to colonize the galaxy (it's easy even at sublight speeds) and that NONE of them have left any trace. No device sending out radio waves, no device that shows as artificial.

I think calling galactic expansion "easy" is a non-standard point of view. I understand that motivation would seem to be high (we're all orbiting something which won't last forever), but space is VAST. What was the analogy in the article I linked? If Neptune's orbit was the size of a quarter, then the nearest star is a football field away? (And the nearest known habitable star is, what, 5× that?) In the face of that obstacle, El Guapo's objections, and time scales measured in billions of (earth) years, maybe motivation isn't actually all that high?

In terms of why-haven't-we-seen-them vs. why-haven't-we-heard-from-them, I find the communication conundrum to be more difficult to dismiss (though not by a large amount — it's not hard to conceive of alternative methods of energy/communication deployment for an advanced race which do not flood the EM spectrum, and for a lesser-intelligent race, a non-focused flooding the EM spectrum isn't really all that efficient when looking across a galaxy).