I Solve Fermi's Non-Paradox: Astronomers Weigh In

[bob012345]

First we should ask what he would have taken as intelligent life...

Fermi's original view was that if they existed at all the galaxy should be utterly filled with them. So the ability to colonize would be the sign of intelligence. But there are still a lot of assumptions built in that. Perhaps they are particular as to what worlds are suitable. Perhaps they don't need worlds at all. Perhaps they have a non-interference policy. Perhaps they examined Earth during the Jurassic period and decided it was too dangerous. But even if they were in our stellar neighborhood, we are only now getting the technology to see hints such as the chemical composition of exoplanet atmospheres. Perhaps they are here but only discreetly and occasionally visit from bases hidden from us observing, waiting but for what?

We know more about the universe since 1950 when Fermi pondered this question. We now know about theoretical possibilities such as the Alcubierre drives and wormholes. It's impossible for us now to use these but what about an technologically advanced society perhaps a million year further along?

https://www.seti.org/seti-institute/project/fermi-paradox

 

[sbrothy]

“Non-interference policy”

And perhaps they’re a bunch of peaceful dirty pacifiist hippies with 30 arms so they can play several guitars while they welcome their new overlords (us) and entertain us while we pillage and burn their planet looking for our McGuffin. :)

 

[DrStupid]

Perhaps they don't need worlds at all.

I would expact that from an interstellar space faring species. However, they do need resources.

Perhaps they have a non-interference policy.

It is very unlikely if not even impossible that there are global policies all over the galaxy. We don't even manage that on Earth even though we have realtime communication. A message from one end of the Milkyway to the other takes 100 thousand years. That's time enough for a lot of civilisations to come and go. That would result in a fragmentation of the galactic population into countless fractions which not only differ in their policies. They wouldn't even realize that that they originate from the same species.

Perhaps they examined Earth during the Jurassic period and decided it was too dangerous.

Maybe many visitors would decide not to land on Earth because it is too dangerous for the dinosaurs. But it is sufficient if only one of them decides to mine Earth for resources. The Chicxulub impact would have been a day at the beach in comparison.

Perhaps they are here but only discreetly and occasionally visit from bases hidden from us observing, waiting but for what?

It wouldn't be sufficient to hide and wait. They would need to protect us from others for many millions of years.

 

[bob012345]

If an advanced civilization did develop Alcubierre drives or learn to use wormholes, messaging would be quick as would travel allowing for a cohesive civilization over galactic distances. That might be the motivation to become a galactic civilization rather than remain a provincial backwater merely interstellar civilization.

 

[BWV]

The basic FP expansionist logic just requires sub-light travel. Self-replicating Von Neumann probes traveling at 0.1C could still have completely overrun the galaxy by now. Megastructures built by K1+ level civilizations would be another indicator that does not require space-opera stellar empires. Additionally, it is rational to assume any technological civilization would become concerned with its eventual extinction as its home star ages

 

[Fred Wright]

The question is, why haven't we seen extraterrestrial civilizations? Well, we have: photo of of floating city seen over Yueng, China

 

[bob012345]

The basic FP expansionist logic just requires sub-light travel. Self-replicating Von Neumann probes traveling at 0.1C could still have completely overrun the galaxy by now. Megastructures built by K1+ level civilizations would be another indicator that does not require space-opera stellar empires. Additionally, it is rational to assume any technological civilization would become concerned with its eventual extinction as its home star ages

The FP doesn't address the motivations at all. Maybe FTL travel is necessary to motivate such a civilization? Basically, we have absolutely no idea how an alien culture would think about themselves or the universe. They might even have religious motivations we couldn't begin to comprehend. Everything we think is biased by our human perspectives.

 

[russ_watters]

Fermi's original view was that if they existed at all the galaxy should be utterly filled with them. So the ability to colonize would be the sign of intelligence.

Is that last sentence from Fermi or from you? Because I don't see how it necessarily follows from what precedes.

That sort of assumption is a good example of why the Drake equation is so wildly imprecise. The assumption of colonization changes the result by many orders of magnitude.

 

[bob012345]

Is that last sentence from Fermi or from you? Because I don't see how it necessarily follows from what precedes.

Sorry it wasn't clear that was my inference. I think it would be a tangible sign of their intelligence to us if we notice the colonization or in other words, the answer to Fermi's question 'Where is everybody? would then be 'There they are!'.

But in 1950 when Fermi asked the question, what metric would he have had to answer it? At that time humans did not have proof of even one exoplanet and that was years before Morrison and Cocconi proposed SETI.

 

[sbrothy]

I’m amused, though perhaps not surprised, that this thread seems to have acquired a life beyond it’s “natural“ expiry date. It’s a “popular physics” topic after all.

 

[happyhacker]

So the argument goes to and fro. Admit it we just don't know. And we never will unless perhaps some race finds those 'wormholes'. Even then we will not know as why would they come in our direction (it's a backwater)? They will head for the Core as that's where all the fun is. SETI will likely fizzle out in a few years.

 

[Keith_McClary]

Once we can see them, it’s too late

 

[DrStupid]

Once we can see them, it’s too late

That would make Fermi's paradox even worse. Once started the expanding colonisation bubble would need at most 100,000 years to reach us. Why isn't it already here? Considering the age of the Milky Way the probability of this scenario is somewhere between 1:10,000 and 1:100,000.

 

[Klystron]

My reaction to Fermi's question varies depends on what I am studying. After finishing books and papers on the difficulties and prerequisites for evolution of (intelligent) life on Earth, I think "We are alone.".

After understanding the latest estimates of cosmic distances, I figure "How can we know?".

Upon studying current estimates of the number and extent of other galaxies, the latest exoplanet discoveries in our galaxy, and reading optimistic estimates of potential life bearing objects in same, I am all "Howdy, Neighbor!".

 

[Keith_McClary]

Once started the expanding colonisation bubble would need at most 100,000 years to reach us. Why isn't it already here? Considering the age of the Milky Way the probability of this scenario is somewhere between 1:10,000 and 1:100,000.

They are considering intergalactic travel.
https://arxiv.org/abs/2102.01522

 

[Paul Davis]

The Fermi Paradox presupposes that alien civilizations either would want contact with others or would not care if others knew they were present. Why would this be the case? I see many possible negatives from such interaction, and not much positive that could not be acquired by passive observation. This doesn't require a Great Filter, just a big "meh".