Breaking down the sci-fi genre

[bill_mchale]

Originally Posted by Steven Lyle Jordan

The only thing I take issue with there is the .01 you've suggested as the number of civilizations born every year. I'd guess at that number being a lot closer to .000000001 or so... see what that does to the calculation? It gets mighty lonely out here.

I have no problems with that number either. The .01 was simply a number pulled out of the hat. but lets use your number. If the average civilization broadcasts for 1000 years, then the odds of such civilization existing at any given time is roughly 1 in a million. The odds of two such civilizations existing at the same time is roughly 1 in 1000000000000. Which means such a pairing of civilizations will likely never exist in this era in our galaxy.

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Bill

[Ekaros]

fc is more interesting part for me, and it does scale. Depending on distance from our planet to theirs. And another good question is it zero for inter galactic distances?

[fjtorres]

Originally Posted by bill_mchale

Which means such a pairing of civilizations will likely never exist in this era in our galaxy.

--
Bill

Uh-huh.
Makes the whole exercise pretty meaningless, no?

One thing modern exoplanet research is teaching us is that the development of life-capable planets is looking to be a relatively "recent" development in the universe's evolution. Instead of us being newcomers on the universal stage, we might just be the precursors of things to come.

That should lead to some interesting new stories.

[kennyc]

Originally Posted by fjtorres

Uh-huh.
Makes the whole exercise pretty meaningless, no?

One thing modern exoplanet research is teaching us is that the development of life-capable planets is looking to be a relatively "recent" development in the universe's evolution. Instead of us being newcomers on the universal stage, we might just be the precursors of things to come.

That should lead to some interesting new stories.

Hmmmmm........

[fjtorres]

Originally Posted by kennyc

Hmmmmm........

Yup.
When the Eddorians come calling its going to be up to us to keep them at bay.

[kennyc]

Pretty damn scare to think of the human species as being the elders of the universe.

[Steven Lyle Jordan]

Originally Posted by kennyc

Pretty damn scare to think of the human species as being the elders of the universe.

The wisest man is born a mewling child.

[kennyc]

Originally Posted by Steven Lyle Jordan

The wisest man is born a mewling child.

[fjtorres]

Originally Posted by kennyc

Pretty damn scare to think of the human species as being the elders of the universe.

James Blish (Cities in Flight) and Poul Anderson (Tau Zero) both played with the concept but not in depth.

[wodin]

Having one eye that works reasonably well, and the other not so much; it doesn't work too well for me.

OOPS! Wrong thread!

[bill_mchale]

Originally Posted by fjtorres

Uh-huh.
Makes the whole exercise pretty meaningless, no?

Well keep in mind the number I gave was based on Steven's estimate of the rate at which new civilizations are born.

One thing modern exoplanet research is teaching us is that the development of life-capable planets is looking to be a relatively "recent" development in the universe's evolution. Instead of us being newcomers on the universal stage, we might just be the precursors of things to come.

That should lead to some interesting new stories.

Well lets keep in mind that a lot of exoplanet research is still mostly speculation. Yes, we are discovering planets at a terrific rate, but our methods are still biased towards detecting big planets in tight orbits around their stars. As for life? Well, that is just a major crap shoot still... at least until we reach the point where we can take spectra of planetary atmosphere.

--
Bill

[fjtorres]

Originally Posted by bill_mchale

Yes, we are discovering planets at a terrific rate, but our methods are still biased towards detecting big planets in tight orbits around their stars.Bill

The Kepler transit method used by NASA can detect smaller and further-out planets; it just takes longer because they need to to track the star for multiples of the planet's orbit. Give'em time to acquire the data.

Beyond that, and bearing on life-probabilities, is what we're finding out about planet formation processes and the (limited) amount of time that the planet-formation clouds can survive. And about the composition of those clouds. The latter suggests that earthlike planet formation requires a lot of heavy elements in the cloud which requires supernova ejecta from second or third generation stars. Which in turn suggests there may not be many earthlike worlds that are older than Earth.

More data is needed to refine the models but so far it doesn't look like the older stars are good places to look for earth-like worlds.
(Very low odds for a Darkover or a Krypton, for example.)

[Andrew H.]

Originally Posted by fjtorres

Beyond that, and bearing on life-probabilities, is what we're finding out about planet formation processes and the (limited) amount of time that the planet-formation clouds can survive. And about the composition of those clouds. The latter suggests that earthlike planet formation requires a lot of heavy elements in the cloud which requires supernova ejecta from second or third generation stars. Which in turn suggests there may not be many earthlike worlds that are older than Earth.

This is my understanding as well. Although it may not matter much - behaviorally modern humans didn't arise until about 50,000 years ago; the oldest cities about 12,000 years ago; writing arose about 5,000 years ago; and e-ink readers only about 6 years ago. :-)

So on a comparable earth-like planet, it would be trivial to encounter a species with a civilization 100,000 years older than ours. Assuming equivalent development, that would mean that they would have to have gotten started only .0025% earlier than we did.

Which might make our listening for radio waves the equivalent of a primitive tribe trying to detect other intelligent life by listening for their drums.

[bill_mchale]

Well, lets keep in mind that older is a relative term when we are talking about stars. Our Sun is roughly 5 billion years old, the Universe is about 14 billion. But the stars that cause Supernovas actually have much shorter life spans (at least the ones that are not caused by white dwarfs in binary star systems). Thus I suspect there well could be stars that are 7-8 billion years old that have everything that is needed to form life.

Also lets keep in mind, that life might develop towards intelligence more quickly than it did on Earth. We have had life on Earth for at least a 3.4 billion years, and complex life has existed for the last 600 million or so. I think there is probably enough time that it would be quite remarkable if we were among the very first civilizations in the galaxy... unless of course we are unique.

--
Bill

[bill_mchale]

Originally Posted by Andrew H.

Which might make our listening for radio waves the equivalent of a primitive tribe trying to detect other intelligent life by listening for their drums.

They might not hear our drums, but they might hear our airplanes, automobiles, and trains.

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Bill