Where is everybody?

[Joaz Banbeck]

It has been over sixty years since Fermi asked "Where is everybody?" Recent data from the Kepler telescope suggests that there are about 500 million planets within the habitable zones of their parent stars in our galaxy - far more than most atronomers expected. While this figure does not plug directly into the Drake equation, it does affect the eventual solution. And that number looks even more perplexing now.

So where is everybody?

[rubin427]

What tools do we have that could directly observe other civilizations?

My understanding is even recently when "earth like planets" have been found it's by waiting for the planet to orbit between us and it's star. When the start appears to get dimmer, we know that's really a planet in the way, blocking some percentage of light. If it happens periodically, we can calculate the orbit, guess at the mass, and so on. Finally, this implies that if a planet's plane of orbit is perpendicular to our line of observation, we can't see that planet at all!

If there is a large city on that planet - we have no tools to observe that.

I think all we can really say with certainty at this point is that we don't think any space men are blasting us with strong radio waves.

Also, seti began operations in 1985. That is so frighteningly brief.

[fwiffo]

We've only been broadcasting for about a century out of ~5 billion years of our star-system's existence (0.000002% of the total span), and only seriously listening for extraterrestrial signals for a couple decades. That's a pretty narrow window, and the odds that some other civilization's window lines up with ours may be pretty small.

[Chew Terr]

This makes me want to play alpha centauri.

[Loons]

I always think in addition to whatever other messages we're broadcasting into space, we should be sending out;

"On 19x19, if you play R17 we play D16."

[TMark]

This makes me want to play alpha centauri.

Mornington Crescent!

Best wishes.

[daniel_the_smith]

No alien civilizations have substantially colonized our solar system or systems nearby. Thus among the billion trillion stars in our past universe, none has reached the level of technology and growth that we may soon reach. This one data point implies that a Great Filter stands between ordinary dead matter and advanced exploding lasting life. And the big question is: How far along this filter are we?

Unfortunately one of the following is likely to be true:

1. Something makes it really hard for a species to evolve as far as we have, making civilizations like ours incredibly rare.
2. Something we haven't yet accomplished is quite likely to destroy our entire species.

The full argument is here. I find it fairly persuasive. http://www.webcitation.org/5n7VYJBUd

Edit: Wikipedia lists some counter-arguments: http://en.wikipedia.org/wiki/Great_Filter

Edit 2: You should also read about the Fermi Paradox: http://en.wikipedia.org/wiki/Fermi_Paradox

[Fedya]

Where is everybody?

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|I'M OVER THERE|                             +------->*
+------+-------+                             |
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[Joaz Banbeck]

We've only been broadcasting for about a century out of ~5 billion years of our star-system's existence (0.000002% of the total span), and only seriously listening for extraterrestrial signals for a couple decades. That's a pretty narrow window, and the odds that some other civilization's window lines up with ours may be pretty small.

Broadcasting is not then only means of comminicating. Indeed, since signal strength decreases in proportion to the square of the distance, radio is not really good for long interstellar differences. Self-replicating probes are better: http://en.wikipedia.org/wiki/Von_Neuman ... ann_probes

[gowan]

Examination of the geological record on the planet Earth suggests that species typically last around two million years before becoming extinct. Homo Sapiens is pushing that number right now. Not to say that humans are going to become extinct over night but we'll need a good argument for why humans will be around for much more than a few hundred thousand years There are so many things that could do away with us: pandemics, nuclear war, climate change, asteroids colliding with the Earth, etc. I guess we'd better play go while we still can

[jts]

The Drake equation has always seemed very unhelpful to me. Any equation with so many perfectly unknowable variables is useless. Even if I spot you an extremely large reservoir of Earth-like planets (which is far from certain at this point), we still don't have any real idea of the rate of abiogenesis (or the rate at which life is wiped off of previously hospitable planets), the rate at which species suitable for sentience evolve (or die off), the rate at which sentient species evolve out of suitable nonsentient species (or die off), the rate at which they become capable of interstellar contact, the rate at which try to engage in interstellar contact, the rate at which they succeed...

And not only can the Drake Equation not tell us anything about the values of any of these variable, the equation can't even assure us that these are the only variables of interest.

(By comparison, imagine an isolated Pacific Island which had forgotten its history of ocean-faring trying to deduce a similar equation to explain the absence of outsiders. What are their chances of even correctly identifying all the relevant variables? Or even one of Brazil's modern-day "uncontacted tribes"... would they remember to include a variable for "creation of a powerful political entity which forbids contact with us to protect our culture and our rights"?)

My instinct is that no civilization ever solves its domestic problems completely enough to invest heavily in interstellar communication/exploration that could only bring benefits after centuries, at best.

[hyperpape]

And not only can the Drake Equation not tell us anything about the values of any of these variable, the equation can't even assure us that these are the only variables of interest.

If you convert the Drake equation to a lower bound and treat it as an expected value it is almost true as a matter of pure logic & probability.

[jts]

And not only can the Drake Equation not tell us anything about the values of any of these variable, the equation can't even assure us that these are the only variables of interest.

If you convert the Drake equation to a lower bound and treat it as an expected value it is almost true as a matter of pure logic & probability.

Do you mean upper bound?

[Jordus]

This article relates to the attempt at communication mentioned earlier...

http://www.ibtimes.com/articles/109081/ ... i-meti.htm

[daniel_the_smith]

The Drake equation is more a way to organize our ignorance on the subject than anything else. Drake said this himself, apparently.