I think it’s fairly obvious: life is an inevitable phenomenon, and highly intelligent life follows, but the universe is extremely vast and the conditions for life to exist are rare enough that the physical distances and are literally astronomical against the light speed limit. So there might be several life forms out there capable of seeking out and contacting other life forms, but that’a another level of steep probability- even if there were fifty thousand such life forms, and their search lasted hundreds of thousands of years at near light speeds, the vastness of the universe really just makes the chances of them coming across us and contacting us fairly slim. The speed of light is a pretty strict limit.

actually i dont think there is any "contradiction between the high probability of the existence of intelligent extraterrestrial life and the lack of evidence for such", space is just too big and our instruments not good enough.

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

how long have we had radios?

vs

radio signal travel time?

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https://en.wikipedia.org/wiki/Arecibo_message

The message was broadcast into space a single time via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo Telescope in Puerto Rico on 16 November 1974.[1][2] The message was aimed at the current location of M13, about 25,000 light years from Earth, because M13 was a large and relatively close collection of stars that was available in the sky at the time and place of the ceremony

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what if they just don't want to talk to us?

Either were alone or were not

Either option is terrifying

This always brings me back to the Dark Forest Theory . Wild for the imagination but I think the simpler one of space=humangous big is much more likely.

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That's not really the issue wrt The Fermi Paradox. It's not asking why seti searches haven't found any intelligent life out there. It's asking why isn't intelligence already evident everywhere.

The great filter is a possibility, but an interstellar civilization would have not only solved FTL, but FTL communication as well. Using current techniques and technology would be effectively like trying to use smoke signals in places of satellite communication.

My bet is we can't find them because we're too technologically primitive to even notice them, let alone communicate.

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Rare earth, Great Filter, light speed being max speed, space to vast to explore combined with no actual point in exploring space with probes.

A combination of those.

There's this and also time. Advanced civilisations could have risen and perished in billions of years. It only took us something like a billion years from simple multi-celled organisms to space flight. And it's really a tiny speck of time we've been sending out radio waves or anything that might be picked up by someone.

There could have been inhabitants a couple of solar systems over and we'd probably never know (at least not yet).

travelling at or near lightspeed isn't necessary as a component of the Fermi Paradox so not being able to travel at those speeds can't be a solution to it.

Why do you think FTL is solvable?

There is nothing indicating FTL is solvable, except fiction.

Harold White and Sonny Judy, plus Miguel Alcubierre would all like words about that.

You sound like the doubters on the beach at Kitty Hawk.

My pet theory is that if you zoomed out far enough, we're all (meaning us and any other distant life) sub-organisms that make up a much, much larger organism...and in turn, that larger organism is a sub-organism of another much, much, much, much larger organism.

So far as we know now. But what we know now is doubtlessly incomplete.

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You must be confusing science fiction with reality.
There is no FTL device, even theoretically conceived, that does not require magic.

We knew flight was possible, because birds fly.

FTL has never been shown to exist in nature, and our best scientific theories also prohibit them (unless you add magic).

"Heavier than air flight is impossible..."

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It is assumed that:

1. It is possible to travel for thousands of years in space, which might be impossible, even for machines.

2. It is assumed there is anyone even wants to do it, when there might be no point in doing it.

But I personally think the great filter and rare earth hypothesis are enough. Us being alone in the Milky Way is absolutely possible. Us being alone in the universe is possible, but irrelevant, we will never be able to do any meaningful interaction with any extra-galactic civilizations.

"said local village idiot" - while all intelligent people before even the pyramids of Egypt knew that "heaver than air flight is doable, because birds do it all the time".

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Ah... resorting to insults because you're too closed minded. Got it.

Do you think heavier than air flight is impossible?

In any case your logic is flawed:
X stating incorrectly Y is impossible, does not mean Z is possible, even if Z is though to be impossible.

FTL is just pure fantasy at the moment, sorry to say. Keep dreaming though.

Outright ignoring the very real scientific results of the White-Juday Laser Interferometer study. Nice. Yeah, you're real intelligent.

I suspect that while we will soon discover that simple, prokaryotic life is common if not abundant, the conditions needed for complex (let alone intelligent) life are quite rare. I have no doubt that there is intelligent life elsewhere in the universe, but I’m skeptical about there being any in our own galaxy, let alone close enough to swing by and visit.

EDIT: It’s also worth pointing out that our definitions of “intelligent” and “life” could be (and likely are) extremely narrow and incomplete. In fact I would say that if we did encounter intelligent life, there’s a good chance that at first we might not even recognize it as being alive, let alone intelligent.

As I said, keep dreaming and hoping.

People doing simple experiments claiming X, Y, Z of impossible things happens fairly often, and they all fail to be reproducible or conclusive.

Nobel Price for anyone out there showing anything even close to FTL being a thing.

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I think the Drake equation needs a tweak on the last term 'L', the mean length of time a civilization can communicate. It really needs to be something like the ratio of L over the time period a civilization can arise. If the numerator is 1e5 years and the denominator is 1e9 years. The Drake equation then starts to represent the number of possible civilizations existing in the same time period (a reduction of 10,000X in the example given).

I like your theory. And if true, I find it entirely likely that the larger organism wouldn't have any idea that its sub-organisms were conscious - or perhaps that they even exist at all. The sub-organism environments might just be too damn small - like sub-particle small.

Then again I'm just riffing and have no idea what the hell I'm talking about.

The conclusion that there should be plentiful intelligent life is based upon probability of large numbers. Even if there were a trillion planets with intelligent life in our observable universe, that’s still less than one planet per galaxy. And there are about 100M stars in a galaxy (1T in Andromeda!), and dozens or more planets around most stars. So I don’t see the paradox. Advanced life is obviously incredibly sparse, and if there is one in the Andromeda galaxy, that’s still 2.5M light years away. Homo sapiens weren’t even around when the light we see from it today left that galaxy.

Unlike heavier-than-air flight, this isn't in the category of a technical problem yet to be solved. It's more along the lines of not being able to reach temperatures below absolute zero.

By all understanding, FTL travel between two points in space appears to be impossible even when attempting to bypass direct FTL travel through that space via wormholes or Alcubierre drives. Alcubierre himself has doubts regarding his drive, indicating it has the potential to violate causality, a point supported by Prof. Allen Everett. Such violation is anathema to most cosmologists and physicists.

In other words, the speed of light is set not by light itself, but by causality. It is deeply fundamental to the nature of the universe. Even were FTL travel possible, it'd only be through phenomena such as multiple forking universal timelines, that is, one way trips out of "our" universe.

Meanwhile, beyond this somewhat dated paper (PDF) refuting White and Juday's claims, I couldn't find any refereed papers or sources for their interferometer. Have you one to provide?

I think your point is very much a possibility, BUT why do you think intelligent life is rare? Even on Earth humans were not the only intelligent humanoid species. Neanderthal was believed to have been as intelligent as humans. So if intelligence has happened at least twice just on this planet, I don't think it's a stretch to believe it's happened elsewhere.

I think it's a mix of everything, life is likely very common, intelligent life like humans is likely very rare.

Mass extinction events happen every so many tens of millions of years so we have a limited time to advance our technology to the point where we are immune to it happening to us.

I am surprised humans haven't destroyed ourselves yet considering nuclear weapons, bioweapons and other WMD's exist.

Our technology is good but is it good enough to detect life on another planet?

The universe is unimaginably big and the distances between civilizations may be too great. I feel like our technology is only good enough to detect alien civilizations if the alien civilizations sends us a direct message with powerful equipment aimed right at us.

We haven't really been looking that long, maybe messages have already gone by. Maybe we aren't interesting enough to send messages to, maybe it's not wise to call out to darkness.

I think there are plenty of great reasons why we haven't directed alien life yet, but I am 100% confident it's out there. There are trillions of galaxies and each galaxy has hundreds of billions to trillions of stars, I just doubt we are that lucky to be the only planet with life.

Two species that were so closely related that interbreeding was possible, and archaeological evidence suggests that Neanderthals copied the tools and practices of Homo sapiens rather than creating their own, so I don’t think that quite counts, but I digress. If a species of dinosaur or therapsid had built cities and spaceships (which would be cool, but there’s no evidence for that) then that would be a different story.

Don’t forget the radius… It is roughly 50 or 60 ly as early radio transmissions were to weak to get far enough without being weaker than background noise… Therefore we can only assume there is no intelligent life in a radius of 25 to 30 ly as they could have answered by now. That is just a super small area of space… We can only listen to them at this point…

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What if there is lots of intelligent life What if we humans are the most advanced Somebody has the be.

Maybe the equation is wrong, and doesn't take other variables into account. Maybe the numbers plugged into it are wrong.

Forget the paradox. Why would extraterrestrial life even want to contact us. If they are advanced enough to contact us, maybe they have a “prime directive” that prohibits interference. Since we would be so behind their technology. Or maybe they want nothing to do with us. We treat each other with such disrespect. We allow poverty and give no medicine to billions around the world. So even with the Fermi Paradox, would you want to contact this planet?

It has to be great filter. Given billions of years head start even if one civilization made it then galaxy would be filled with colonies in every soloar system...all intelligence must go way of dodo, just like were going. Technology evolves so much that our ape brains cant control it...or its simply we pollute the planet to the point were we devolve and are unable to leave.

I have thought about this too. It’s a fun one.

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I'm getting tired of all the attention given to the Fermi paradox.

Firstly, it's not a paradox and secondly, it's based on a lot of assumptions that are not supported by evidence.

It's even questionable that it's even Fermi's.

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There are lots of possible answers. It could be that intelligent life is pretty rare, so that even if there was a species out there building dyson spheres or doing other crazy things in a far distant star system we wouldn't be able to detect them. Or maybe there is a sociological explanation, like civilizations tend to be unstable and collapse in on themselves before they can become type 1.5 civilizations. Or maybe most intelligent species are trapped in their solar systems or their home planet, that interstellar colonization will never be economically feasible.

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Then we have a big torch to carry.

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I think this is more like 'impatience paradox'. With our current technology we have extremely little chance of detecting any intelligent life.considering the formidable obstacles created by one single barrier - the distance measured in light years. Once we have ,at least, a few hundred thousands of years of observations AND NOT just 50, we will be able to talk about the Fermi paradox.

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What if civilizations millions of years ahead of us who already mastered time and space travel just aren't interested in us enough to show us how ?

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I think the biggest variable people downplay is the extreme youth of the universe. The universe has not been able to harbor baryonic, carbon-based life for all that long since it requires at least the second generation of stars to develop. Somebody has to be first and it very well could be us.

This study explains my favourite solution yet.

The paper I hyperlinked explores the possibility that low mass k-type stars are similar to our own g-type except are more stable and can outlive g-types 3-6 fold. It also explores k-type distribution density in the galaxy and concludes they are more highly concentrated and much closer together in the centre of the galaxy. Given these facts they propose that there is a migration pressure for space faring galaxies to move in towards the centre of the galaxy, and if there is a “Galactic Club” of aliens chilling out somewhere doing awesome shit, then they would have most likely just colonised the centre galaxy k-types and left all the other solar systems alone. Hence we are sitting on an outer solar system g-type that is not worth the time or energy to colonise, hence we appear alone.

No paradox becasue of 3 things:

1. Unfathomably huge universe
2. TIme scales - billions of years
3. Realtively slow max speed of travel / information propagation

For example, consider "someone someplace else" detecting earth. How long have we done anything that would be detectable as a sign of intelligent life? Lets be really genererous and say 500 years. Well the universe is about 13 Billion years old, so we would only have been detectable in a teeny tiny fraction of the age of the universe. And the chances of being detected are further dwarfed by the extremely low chances of some detector looking in our direction is that same teeny tiny window of time. And where would these detectors have to be? If we've been detectable for 500 years then the detectors would have to within a 500 light year bubble around earth. A teeny tiny fraction of our own galaxy. Forget other galaxies (our closest neighbor galaxy is about 25000 light year away which means they could not detect us for another 24,500 years). And then there is that part of the universe we will never see at all because it is moving away from us faster than light speed (god knows how big that is). My point is that the chances of any contact (or even detection) are virtually zero. The universe is probably full of life. All of it alone and isolated. Forever.

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This is the truth: we are actually the first civilization that looks for ET life. There will be others but they're not 'here' yet.

We won't find them, they will find us.

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

That advanced civilizations aren't complete morons...because that is the whole premise the Fermi paradox is based on: "Advanced civilizations can do all kinds of stuff but are mentally (and technologically) more incompetent than humans are now"

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But does that mean there are as many universes one layer up from each layer of organisms as there are organisms in any of those universes

According to my completely uninformed, pet theory that I pulled out of my nether regions - yes.

If there really are civilisations that have survived on the billion year time-scales of our universe, the fact that they're not clearly visible everywhere we look is a distinct choice they've made. Space is big but time is much bigger.

What is "life"? What is "intelligent"? These words have a very fuzzy and arbitrary meaning

True but the time our little brains have been able to potentially detect something is a tiny sliver of the history of the university right?

Honestly though do you ever wonder why there are SO FUCKING MANY pointless stars and planets? Seems weird if this was all “intelligently” designed.

Intelligent/advanced life is entirely different than intelligent design. We have proof of the former in ourselves, and it’s a testable theory even if we haven’t found any signs yet in the vastness of space. The latter — intelligent design — is faith and not a field of scientific study.