quote:
So that limits the search to only civilizations that have discovered radio and the broadcast has had enough time to travel to be detected on earth.

It's more subtle and restrictive than that.

Let's say that a star is 10,000 light years away and it had a thriving civilization around it making all kinds of noise when it was suddenly wiped out 10,500 years ago. We'd never know they existed because the last radio signal would have reached us about the time Da Vinci was running around.

They have to exist at a point in spacetime that allows evidence of their existence to reach us at a point in OUR history where we have the technology to detect it and the intelligence to recognize it as something different from all the other radio (or whatever medium they're using) noise in the universe.

This post was edited on 9/8/20 at 7:39 pm

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Posted by Darth_Vader

A galaxy far, far away

Member since Dec 2011

64523 posts

Posted on 9/8/20 at 7:44 pm to BobLeeDagger

quote:
What’s more frightening, the possibility of advanced alien life existing, or the possibility that we are the only life form in the entire universe?

Easy, the possibility of their being advanced alien life existing. I say that because if there are advanced alien civilizations out there there’s a very real chance At least some are (1) far further advanced than us and (2) hostile and thus a possible threat to our existence.

On the other hand, if we are the only civilization in the universe, then oh well. We go on existing and advancing on our own as we’ve been doing for thousands of years.

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Posted by Zephyrius

Wharton, La.

Member since Dec 2004

7935 posts

Posted on 9/8/20 at 8:23 pm to Oilfieldbiology

quote:
I know 10,000,000 is a massive number, but there are literally billions of stars in the Milky Way alone.

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Posted by Kentucker

Cincinnati, KY

Member since Apr 2013

19351 posts

Posted on 9/8/20 at 10:44 pm to Korkstand

quote:
(given the estimated 100 billion+ galaxies

After Hubble’s deep field views, the estimate for the number of galaxies in the observable Universe went up to two trillion. The size of the observable Universe is approximately 93 billion light years in diameter.

The size of the entire Universe, using Alan Guth’s Inflation Theory is 10^23 times the size of the observable Universe. It is to the observable Universe as the observable Universe is to an atom. Really big.

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