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

[cannongray]

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

Title says all.

[Prometheus]

I don't understand why it's considered a paradox. If you take something like the Drake equation, there are lots of parameters we have little idea about, such as fraction of planets suitable for life on which life actually appears or fraction of intelligent life that develops detectable technology. It's quite possible that these parameters are such that a technological civilisation on average only appears, say, 0.7 times in the entire life a galaxy.

[Bufofrog]

There is really no way to economically and safely travel to other stars.  I wonder how many planets would have a mix of gases that would allow humans to breath, I would wager that it is very few.  So the aliens aren't here because you can't get here from there.

[dimreepr]

Quote

“Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.” - Douglas Adams,

The galactic hitch-hiker...

[exchemist]

7 hours ago, cannongray said:

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

Title says all.

In space travel, the numbers are awful. (Douglas Adams)

These other civilisations may well have decided, quite coolly and rationally, that spending centuries flying through empty space is a pointless exercise.  

 

Oh, ninja-ed by @dimreepr, I see. 

 

Edited April 29, 2021 by exchemist

[ALine]

Maybe the universe is still very young and it takes a while for complex intelligent life to form in analogous "pockets" of it.

[swansont]

I agree space is big and not a continuum of habitable or useful bodies is one part.

And I agree the age of the universe is another. I think we discussed aspects of this before - without a couple of generations of stars you don’t get heavy elements, so even if life arose early on, it couldn’t exploit its environment in a way that would lead to industrialization and space.

And then you have to have intelligent life arise at the right time. If there had been early intelligent life but no abundant, accessible coal or oil around, odds are against them getting into space.

[beecee]

In my opinion, it can be summed up with simply "'Time and distance" They are the two barriers making any inter-planetary/galactic encounters difficult.

[joigus]

I tend to agree with @Prometheus. I find it difficult to see the paradox because there are so many unknowns. Let me give you an example: In recent years it's been discovered that there are microorganisms living underground and in the marine bottoms with life cycles completely disparate from those imposed by the Sun. This suggests that we are barely starting to understand the limits of life in our own planet.

I would add the ethological argument. Namely: Why would another civilisation want to be seen by us? Predation, parasitism, territoriality, and other similar patterns in which one organism takes advantage of another are very common in Nature. Not always or necessarily to the advantage of one, the other, or both.

Then there is the issue itself of how Fermi conceived of the question. It was a very informal argument arising from a conversation, that he later tried to make into a scientific argument, but I don't think he ever made it very rigorous or attempted to do so.

Then came Drake and his equation. That's a more serious attempt at setting up the question. But still, so many unknowns...

And going back to the original argument from Fermi, it sounds suspiciously similar to an argument from silence: We don't see any evidence of this, thereby it never happened. The way in which this kind of argument can mislead you has been extensively analysed in classical studies, archaeology, and all sciences that have to do with studying the past.

[swansont]

Just read an interesting tidbit: the fraction of our rockets devoted to payload in getting to orbit is fairly small, and if you can’t get there, going beyond is a nonstarter. If you live on a planet that has a sufficiently higher g (denser than earth, or somewhat larger radius) then chemical rockets have no chance of getting you to orbit.

[Moontanman]

The fermi paradox can be explained many ways but few of them are really a solution. IMHO time that a civilization is detectable is short, our own planet is slowly becoming very quiet due to our communications becoming digital and less energy is wasted on newer networks. Distance is another problem, it is said that Arecibo could detect another telescope like it's self all the way across the universe or some vast distance but that is misleading. Due to em inference, interstellar dust, and other problems it's doubtful Earth's radio leakage could be detected at the nearest star, military radars might be an exception but the wow signal, one short but powerful series of pulses imitate what receiving a military radar might look like but that is just speculation. The truth is unless someone is sending a powerful beam pretty much directly at us it wouldn't be seen by us nor would we be seen by them.   

Edited June 24, 2021 by Moontanman