1700 Extrasolar Planets and Counting

The thing is when most people hear the term "Earth like" the think of something that resembles the climate of California or something like that.

You want to get technical, a desert world routinely having temperatures of more than 100 degrees or an ice world locked in a permanent ice age that is similar to Antarctica are also "Earth like"

Yes, "Earth-like" is a very inclusive term. Is Venus "Earth-like?" Is Mars?

It looks like terrestrial planets close to Earth's size are pretty common, about 19% of the total discovered by Kepler so far. A good many of those will be outside the habitable zone of their star. And some of the ones that are in the habitable zone will be like Venus. I'd guess that only about 0.1-1.0% of all planets will turn out to be something we humans could reasonably colonize.

Of course, that's still a shitload of planets...

I wonder what the odds are of a system like the one in the Firefly 'verse actually existing...

Well, if the universe is infinite...

Based on the discussion in an earlier thread, probably pretty low.

@ed629 gives a pretty good explanation of why such a system is unlikely in this post: http://www.wordforge.net/index.php?posts/2575164/

Yes, but if the universe is infinite, then it is pretty much a certainty that it exists somewhere--probably even with the exact characters from the show. There's almost certainly a planet where the dominant form of life is inner spring mattresses.

Probability is not evidence.

As far as we know the universe isn't infinite though. Also something being infinite doesn't mean every variation has to happen. For example you can have an infinite string of numbers that doesn't contain a single 7.

Infinite universe or not, there's only a finite possible combinations that matter can take. IIRC, the laws of orbital mechanics make a system like that in Firefly unlikely.

Well, it's one less term in the Drake Equation to fret about....

Yep. But the term that's really going to be difficult to determine--without finding intelligent life--is what percentage of life-bearing planets produce intelligent life?

My best guess at this moment is that life is abundant in the universe, but that intelligent, technological life is exceedingly rare. Something like a 1-in-a-billion occurence in the small percentage of places it can exist, meaning we're probably it in this galaxy.

Of course, I'd love to be proven wrong!

I tend to agree. Intelligence isn't necessarily a good survival strategy in evolutionary terms. And the particular form it's taken with us is probably very different to what it would take elsewhere.

Every Red Dwarf Star Has a Planet—And There Are 200 Billion Such Stars in the Galaxy

http://www.popularmechanics.com/sci...al&utm_source=twitter.com&utm_campaign=buffer

Well, Carl Sagan says that we're a way the universe gets to know itself. Which just means I think I've made the universe really depressed.