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Physics, Astronomy & Cosmology / expansion of space
« on: 17/08/2006 17:50:11 »
The expansion of space (Big Bang scenario) is generally thought of as occuring everywhere. On the other hand, atoms keep their same size, the distance between the earth and the moon seems to be constant, the distance between the planets and the sun is constant, the size of our galaxy seems to be constant, and so on. So, there seems to be large pathches of space which seem to be immune to expansion. Maybe one could argue that "bound systems" do not expand, but why should this be so ? Also galaxies can form clusters and even superclusters which do not follow the expansion of space. So, in the end, our universe is only allowed to expand in some "limited regions" in between all these bound systems. What kind of magic prevents such large regions of space to expand ?