Aliens!

Just thought I'd throw out a poll, for the fun of it.

I say they exist. I think it's unlikely that we'll ever meet them, given the size of the universe compared to its maximum speed, but I find it hard to believe that we're special enough to be all alone.

I voted maybe.

Though I agree with Lourens

Agree. Statistically we just can't be the only sentient beings in the universe given the number of galaxies, stars, planets.

Likewise if there is no way to circumvent the speed of light "barrier", then it is very unlikely that we will ever encounter any other of the sentient species out there.

Well if worm holes exist - then there is life in space. Or would that be hole worms? Most worms are whole. But if you split them, does that make two worms?

Why?

Oh, I see, because there are gazillions and gazillions of planets that we don't know about, so many that there has got to be life on one of them. I guess to figure out the chance scientifically you'd have to figure out the statistical chance of life starting (evolution only starts after life starts - I think - am I correct?) and then make an estimate of the amount of habitable planets in the universe, and then figure it out from there. Do we even have enough information right now to make a guess?

Drake Equation.

http://en.wikipedia.org/wiki/Drake_Equation

Actually, I've heard that the odds of life being created on Earth are so low that aliens must have planted life here. See http://en.wikipedia.org/wiki/Transpermia.

Not necessarily planted - could just be a microbe arriving on a meteor for example.

But that said, although chances of life starting is low, it's not zero.

I looked at the Drake equation on Wikipedia, and it seems pretty arbitrary to me. For example,
ne = the average number of planets (satellites may perhaps sometimes be just as good candidates) that can potentially support life per star that has planets

There are extremophiles that can live in space. They can live on sunlight, or heat, and even if we can't find them on Earth, surely some potential form of life would be able to live in space. That means that any rock in space that isn't too close to the sun to incinerate life could support life.

fi = the fraction of the above that actually go on to develop intelligent life

Do we have any idea of how to test intelligence, let alone how it could start (the Turing test is a test of the perception of intelligence, by definition, not intelligence itself)?

Also, all the variables are unadjusted. What if one variable is more important than another?

Also, all definitions of life that we have are based on life on Earth. What if there is life in a form that we can't recognize (as opposed to Betazoids and Klingons, for example )

There's lots of stuff out there by some pretty eminent researchers, on the Drake equation and its descendants. Google should find them, and may give answers to some or all of your points.

It comes down to, I think, the fact that the Drake equation is the best we have at the moment.

I think this point (that many people bring up again and again) is not relevant.

WE (humans) define, what is life and what isn't. Not because we have the absolute authority about that question for the whole universe, but simply because we need some kind of definition for ourselves. So if we define what we consider life, the notion of a form of life that can't be recognized by us is somehow amusing to me.

I agree on the other points regarding the drake equation. Many of the variables are completely arbitrary guesses, therefore the Equation isn't really meaningful.

To me it is more like an example/a metaphor to help us think about life in the universe: even if we enter pretty conservative values we do not get zero as a result (although that is easily doable as well) and with optimistic values we get plenty of intelligent life in our galaxy alone.

As with most things in nature: the reality is probably somewhere between the extremes

I don’t believe in aliens. So far there is no scientific evidence found related to aliens or alien planets. We are the only technological species in our galaxy.

Science also says something about probability. And it seems to be increasing every year.