Extraterrestrial life

[J. J.]

Probably at least one of the other 10^20 stars in the universe has intelligent life.

You left out a whole bunch of zeros.

[J. J.]

I would suspect that there is "life" elsewhere in our solar system, if only in single cell form.

I would suspect that there is intelligent life out there in out our galaxy.  Whether it can communicate is another matter.

As for the Fermi paradox, what evidence would there be that a survey fleet spend a decade on the planet 200,000,000 years ago?  Why do we assume that these aliens would want to colonize the planet?  We are at the edge of the galaxy, and we not have strategic position.

[J. J.]

Drake fails to take into account the mind-boggling complexity of even the simplest possible lifeforms.  In order for a cell to form from lifeless matter, a process would have to take place akin to a tornado striking the junkyard outside of a Boeing factory and accidentally assembling a functional 747.

Not true at all.  We have good evidence that single celled lifeforms once existed on Mars, and we may soon discover that they, or even slightly more complex forms, still live on the moons of Saturn.

If Earth has taught us anything it is that life is highly adaptable and can form to fit many environments and functions.  Now, I do believe that we had some help in that, but I also have a hard time believing that God created all that crap that we call the Universe and never bothered to fill it with anything else.

I agree with Super, but let's factor God out for a moment.  It looks as if at one point something was alive on Mars.  We think that on one of Jupiter's moons, there might be water and possibly something alive, on a cellular level. 

Now, there are several reasons why we wouldn't see them.

1.  We are fairly close to the edge of the galaxy.   Even if we were closer to the center, half the galaxy is on the other side; most of civilizations might be over there.  We may not be on a trade route.  Further, perhaps the only reason they would seek us out is for raw material,  Any species capable of transversing space may have easier was of getting raw materials.

2.  We're looking for the alien equivilents of I Love Lucy, broadcasts.  This period might only last for about a century and a half of a technological culture.  Even today, we are increasingly using technologies that aren't broadcast, like satellite television.  In 50 years, there may be no more "accidental"  broadcasts coming from Earth.

Assume that a culture about 100 light years from here reached this point 200 years ago.  We might have gotten broadcast 100 years ago, but we were not looking.

3.  Third, is distance.  Assume that a planent is advaning at the same rate as the earth  We won't be getting their I Love Lucy] for another 50 years

[J. J.]

not in this galaxy.

Scientists estimate that it would take between 5 and 50 million years for a race to colonize the entire galaxy.  And we've yet to be colonized, and our sun is a relatively new star.  Therefore it's highly improbable that a very advanced civilization has arisen in our galaxy, unless they're long gone.

I've got to disagree with the idea that an alien race would be interested in colonization.  Building out of system colonies is expensive (in terms of resources) and probably difficult to govern (or control). 

Assume that Galatic Emperor Sloob IV has an empire with 100,000,000,000 Gorfs; also assume that Gorfs are cabon based lifeforms that need air food and water.  If they are capable of interstellar flight, they are capable of doing many things.  They can build stations, settle other planets in their system, "terraforming" them.

They fill their own system up and decide to colonize.  They have a choice:  Planets in a 20 light year radius or earth 100 light years away.

There are probably a lot of planets within a 50 light year radius.  It will be expensive to colonize, because of terraforming, but its still work it.  Maybe there are one or two that are pretty much like Gorfia and don't need much work.

Sloob the Tyrant looks at the situation.  It's going to cost more to send people to Earth, 150 light years away, and ship supplies to it.  It's going to be harder to defend it, if the H'Dok'ofs start trouble (again), that it will be that nice one 5 light years away.  Further, if they revolt, it's going to be easier to supress the planet five light years away than 150 light years away.  He (or She or It) looks at the situation and decides, "Ah, we'll keep it close to Homeworld."

They may be able to keep 20 Billion in their own system, including other planets, space stations, moons, and move the rest into the ten or twelve systems closer to Gorfica.

There probably isn't anyone else within a 35 light year radius.

[J. J.]

I'm trying to be conservative, and assuming that gravity will be a factor.  The moon, for example, will be hard to terraform because there is very little to hold the atmosphere.  Mars, and some of Jupiter's moons are different matters.  Even the moon could be much closer to Heinlein's vision of underground cities.

My particular point is that any civilization that has the ability to cross the distances of space has the technology to really terraform their own system.  Colonialism isn't probably going to be the goal of an alien species.

[J. J.]

The Drake equation, with even somewhat conservative estimates, would yield a relatively large number of planets with intelligent life, and an even larger number of planets on which life arose. Drake himself estimates 10,000 intelligent civilizations.

Consider this very long list of criteria that have to be within very tight tolerences in order for intelligent, complex life to exist.  There are now 154 of them:

http://www.reasons.org/resources/apologetics/design_evidences/200406_fine_tuning_for_life_on_earth.shtml

That list is not what is needed for compex life to exist, but for complex life to exist in precisely earthlike conditions.  If we do find solid evidence of life elsewhere in the solar system, even simple life, we can safely assume that the universe is not so precise that only Earth and Earth clones can support life.

Note that in my example, I've assumed carbon based life similar to humans.  We might be talking about a species that breaths nitrogen, for example, or something based on silicon (with carbon based computers).

[J. J.]

We might be talking about a species that breaths nitrogen, for example

Nitrogen gas (N2) would have zero value for respiration.  The Nitrogen triple bond takes enormous amounts of energy to break.

You are assuming respiration in a carbon based life sense, as seen on earth; the migh have evolved another method.