I suddenly realized that this is actually a coherent question and googled it. 125 billion. This bothers me! Not that the number is too small or too large but that it is a finite number. I guess I've known since I was a kid that if you keep going far enough in a straight line through space you end up at the place where you started, but somehow this hadn't really sinked in and I still thought 'universe' ought to mean 'everything' and thus 'infinite'. 125??
Edit: on second thought, this means that there are as many neurons in your brain as there are galaxies in the universe. Take that atheism!
Random rant brought on by cosmologist Sir Martin Reeves speaking at TED (18min):
3 comments:
you know that the 'infinite' number they present is just to make people stop questioning, to tell the truth they have no idea how many galaxys there is but they can not tell you that beacuse then there are to many people asking questions and then they belive they will die when the endless sky falls down on us!
So there is no 'infinite' number - there is just a relaxation number
That's just the number of galaxies in our "past light-cone", i.e. the part of space-time history we can see. The actual number is anywhere between 125 billion and infinity. And we certainly don't know that space is closed in that way. Spatial infinitude is a definite possibility, and the large-scale spatial curvature which a closed universe would exhibit, if it exists, is so small as to have gone completely undetected.
my physics is (are?) very rusty. what's your academic field mitchell?
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