Hundreds of billions of planets, and this is just our one small galaxy.
Just given the sheer scale of the universe, I think we almost have to be foolish to think that we're the only life forms that exist in the whole thing.
It’s also foolish (no pun intended) to think that the Universe was meant to have life. We tend to believe that life is what gives meaning to all that vastness but Cosmos doesn’t need a reason for its existence, it’s just there.
Furthermore it’s not about just life but intelligent life. Life in form of microbes could be all around the Universe. But intelligent life could be extremely rare or it could be just too early and we could be the first of many species to come. It’s not egoistic to think so, it doesn’t make us feel unique and special, more likely it makes us feel depressed thinking that we are the only ones or the first of many to come.
If you take the Drake equation for example and tweak a couple of pessimistic numbers you realize it doesn’t take long before you come to the conclusion that life is extremely rare. A very good implementation you can find here:
http://www.bbc.com/future/story/20120821-how-many-alien-worl...
I would also like to point to the Fermi paradox. Given the aforementioned Drake equation many scientists have made estimations about the number of civilization in our galaxy. Estimations vary from a few dozen to the thousands. But if there were even one advanced civilization in the galaxy they should already have made contact somehow. That is the basis of the Fermi paradox, you can find more at Wikipedia:
http://en.wikipedia.org/wiki/Fermi_paradox
It is also foolish to take Drake equation seriously or assume that we know what intelligent life is. Drake equation should be used for demonstration purposes only. As a side not, it is good to keep in mind that all we did for ETI search was looking out for a human-like radio signal with a narrow bandwidth, which is probably not the best way to transmit information through the Universe.
If you read the link I gave for the Fermi paradox you'll see that this is one of the dozen explanations on why we haven't been contacted yet by an alien civilization. So, yes, we might be trying to contact the wrong way.
Actually though it's not exactly wrong, we managed to capture once a significant signal that could be of alien origin. It's called the wow signal and you can find more here:
http://en.wikipedia.org/wiki/Wow_signal
The basis of the Fermi paradox though isn't about what we did/do to contact alien civilizations but the fact that even if one advanced existed in our galaxy they should have already found us even if we weren't looking for them. Which brings us back to the conclusion that there might not be advanced civilizations around and life could very well be in the beginning.
As for the Drake equation it's not a law of physics. It is just a way to estimate the number of habitable planets in the galaxy and from there to make an assumption of the number of alien civilizations able to make interstellar contact.
Ugh. It is not unreasonable to take the Drake equation seriously. You just have to correctly understand what purpose it was supposed to serve.
The equation is not about calculating the probability of intelligent life. It was about identifying what information needs to be gathered do that you can calculated the probability of intelligent life arising.
In other words, the equation was created to help guide research, not to answer the question itself directly. As a guide to research, I think the equation remains highly relevant.
This is an interesting philosophical point. If the Universe is capable of supporting life, if indeed life is fairly common in the Universe then couldn't one say that life is fundamentally implied in the laws of physics and so forth?
Yup. It absolutely boggles my mind every time I look up at the stars. Especially when I'm out in the country with no light pollution, and you can clearly make out the light streak signifying the plane of the Milky way through the sky.
> Just given the sheer scale of the universe, I think we almost have to be foolish to think that we're the only life forms that exist in the whole thing.
This is why I like the Drake equation [0]. Even if it is not perfect, it is inherently understandable by the lay person when we are discussing such matters.
Just given the sheer scale of the universe, I think we almost have to be foolish to think that we're the only life forms that exist in the whole thing.