Infinite number of planets with life

[Hovik]

Actually, we know not only how big across the universe is, but also how much mass is in it.


This is also untrue. The habitable zone is estimated to be some 2.28 AU wide. Furthermore, the Earth's orbit is elliptical, so its distance from the sun varies between 152 million kilometers at its aphelion and 147 million kilometers at its perihelion. That's certainly not a difference of centimeters.

quote n1, I'm going to search about that when I can, but how do we know that? what comes after the universe? it has some kind of walls? what the name of the theory? or it is definitely like that? because I see all the theories, including the existence of a god as all possible ( I see the faith ones less rational....) just no one can prove it...

quote2 interesting and good to know but that's not the point, if the position of our orbit on the sun is not the the factor for life in earth, well a factor there is, magic, superpower or simply lucky are the lasts on my list...(but still in the list...) and the fact that the earth is here tell us that there is a probability....

thanks for the reply

I'm not wholly equipped to answer your questions as well as I'd like, but I can tell you that there is an "edge" to the universe in some sense. The universe is simply a space that expanded during the big bang. Outside of that space there isn't really anything, so far as we know. There could be other universes alongside ours, but we really don't know right now.

The position of our planet around the sun is indeed the factor that determines its habitability, but the range of distance from the sun in which the Earth could remain habitable is quite large (as I've previously said).

You seem to have a natural curiosity for this kind of thing, so I encourage you to perhaps read some books on elementary physics or, if you've an hour or so to kill, watch this lecture by a physicist named Lawrence Krauss. It might not give you specific answers to your questions, but you would definitely learn a lot about the modern state of our understanding of the universe, how it came to be, how big it is, and how scientists are able to figure all of this stuff out.

http://youtu.be/7ImvlS8PLIo