Where is everybody? (Fermi paradox)

[Olgar Shiverstone]

Our galaxy is mostly empty space on a human scale, and we're barely explored our own solar system. We just poked a tiny finger outside our star's gravity well. Even signals from intelligent life close by in a galactic sense might not have reached us yet. (Or, what Morrus said.)

Why do we assume that other intelligent life will look, think, or communicate like us? Maybe they use point-to-point laser communication, or use broad spectrum IR that is so red-shifted by the time it reaches us it has faded into the background radiation. Maybe they communicate by wiggling gravitrons, emitting Higgs bosons, or with massive bursts of radio waves from dying stars.

We're pretty arrogant as a species to extrapolate a massive paradox from a data set of one.

 

[Kramodlog]

And yet here we most emphatically still are, and thinking about colonization of Mars.

Yeah, that is just a scam. The tech ain't there yet to keep them alive, well fed and protected from solar winds and other radiations. Heck, what rocket will they use? A delta rocket? That thing as a pay loa of 500 kilos. et two people in there and I'm pretty sure they do not have enough food to get to Mars.

Plus there are no reason to send people there, aside from "just because we can" (which we cannot). No resources to extract that could to justify the expenses to send people there and keep resuplying them. Humans like to migrate and colonize, sure, but we always followed some resources (hence Antarctica being uninhabited).

 

[Jester David]

Radio signals are not particularly strong, being unable to easily reach across the planet. I can barely get a strong signal from the city out where I live in the 'Burbs. A lot of radio noise would become hard to distinguish from background radiation.
Realistically, the lifespan of radio is short. We've had commercial radio for less than 100 years and it's already being phased out for satellite and cable transmissions. In ten to thirty years Earth will all but be a transmission dead sphere.
We were only really listening to the skies for half a century, and could easily have missed the window of signals.

That's assuming other races develop radio at all. Radio might not work as well for a race lacking strong ears, or without auditory communication, or without an atmosphere that reflects radio waves limiting their use. Or they might stick with wired communication.

It's also possible extraterrestrial life might not be interested in communicating, being more introspective. Or life might be common but advanced alien life might be rare.

I believe alien life is likely common. The universe us likely lousy with life. Intelligent life is likely much rarer.
Intelligence requires environmental stability that isn't continually wiping out life. A big gas giant like Jupiter sucking up asteroids also helps. But there needs to be enough changes that various races are forced to re-adapt and alternate races are allowed to take over. Dinosaurs ruled for millions of years without developing intelligence.
Technology also requires some other factors. If you can't forge metals you're at a disadvantage, and worlds lacking appropriate metals would be all but stuck at the Stone Age.
North American civilizations started at the sane keel of advancement as the old world countries but fell behind for a few reasons. A lack of riding animals (horses) was likely one, as that hindered larger land empires. And, in North America, there were few cities and permanent settlements. Multiple city-states are vital for preventing knowledge from being lost when obey civilization falls. When Rome fell much of its knowledge was preserved by the Arabic empire. The multiple continents really help defend human civilization from being ended by natural disasters.
So much of human technology comes from warfare. A less tribal species might not have advanced nearly as fast.

 

[Umbran]

Where pretty young as a species. Homo sapiens sapiens is about 100,000 years old...

I believe the fossil record places anatomically modern humans about 195,000 years ago, and genetic divergence from the last ancestor of all modern populations is estimated at 200,000 years.

 

[Kramodlog]

I believe the fossil record places anatomically modern humans about 195,000 years ago, and genetic divergence from the last ancestor of all modern populations is estimated at 200,000 years.

I think that is homo sapiens idaltus.

 

[Umbran]

Why do we assume that other intelligent life will look, think, or communicate like us?

Interstellar modes of communication are governed more by physics than by the form of life. There are only so many ways to get a signal between the stars.

Maybe they use point-to-point laser communication, or use broad spectrum IR that is so red-shifted by the time it reaches us it has faded into the background radiation.

That latter one of those is simple - the cosmological red-shift doesn't happen within gravitationally bound systems. The galaxy is not expanding so that it would red-shift.

Point-to-point laser communication could be done, I suppose. It would require you know where the target is - so it is only good for talking to your own people.

Maybe they communicate by wiggling gravitrons, emitting Higgs bosons, or with massive bursts of radio waves from dying stars.

The Higgs bosons would be a lousy vehicle for interstellar communication - they have a a half life of almost nothing. Neutrinos, fine. Not Higgs.

And, well, if the only way you have to communicate between the stars is for a star to blow up... there's a problem. You'd ave to travel to that dying star to send your message, and you could only send it when the star is dying. So, why didn't you just travel to the place you wanted to talk to, when you actually wanted to talk?

And, by the way, our radiotelescopes would catch the latter, and SETI spends a lot of effort to find non-randomness in radio signals from space. This is a way we could likely detect.

 

[Bullgrit]

So, the galaxy and universe may, indeed, be full to the brim with intelligent civilizations, but universal physics means that we will never actually find or contact or meet them?

Bullgrit

 

[Kaodi]

If Seth Shostak of SETI is to be believed we may be between five an fifteen years from discovering another civilization in our galaxy depending on whether there are thousands or tens of thousands out there.

 

[WayneLigon]

Right now just getting off this world is nearly impossible. We can't even colonize our own satellite.

Sure we can. It's actually fairly easy to colonize the Moon, and we could have done it with 1960's tech, but we don't want to spend the money to do it.

For Fermi: I think it's silly to think we're alone in the universe, but the paradox is troubling.

Maybe the problem is psychological. It might be that we have an unusual outlook. We think of 'curiosity' as one of the defining traits of intelligence, but maybe it's not. Maybe few other species ever have the desire to go into space or explore the unknown, or constantly expand their tech capabilities - maybe the 'norm' of the universe for intelligent life is to create enough tech to satisfy the basic needs of food, shelter and safety - then stop. Most civilizations might dead-end in the early Bronze Age. Maybe most worlds with intelligent life are very 'kind' to them; planets with little or no seasons, with plenty of food and water, with little in the way of hostile bacteria or parasites - maybe most civilizations never see the need to tailor their environment to themselves. Without a super-complex infrastructure, nothing much happens when it gets knocked over by a plague or climate change or other sort of disaster.

Maybe 'radio' is indicative of a general, conceptual-level technological dead end we haven't recognized yet, much like the 100-year detour chemistry took with Phlogiston. People don't answer because it's pretty pointless for them to do so: we can't detect what they are saying, and we wouldn't have anything worth trading even if we did.

More ominous might be the 'war-verse' theories, where rogue civilizations created something like a Berserker fleet that homes in on people with radio transmissions and obliterates them, so everyone stays very, very quiet.

 

[tomBitonti]

Side question: What are the parameters for interstellar communication?

Haven't found simple answers. This probably has some, but I'm not able to tease them out of the text:

http://arxiv.org/pdf/1305.4684.pdf

The table 2.1 on page 41 looks interesting, and has values of 664KW to 753MW for a 1000 ly transmission using an Arecibo type antenna. I'm still puzzling over the chart to know what those values really mean.

Thx!

TomB