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See also Question 619 .

On one interpretation of what you say, I don't think your belief is correct. I would wager that most scientists believe rather that the laws of physics, as they are presently formulated, are not quite (or in some cases, not even close to being) correct. Our experience of trying to know what the laws of physics are and then finding ourselves surprised to learn that they aren't quite what we thought gives us some reason to believe that our best theories now don't quite get things right either. But perhaps your question is rather about the scope of the laws of physics. Perhaps you're wondering whether certain laws hold in this corner of the universe and other laws hold in other areas of the universe. That's an empirical question, of course, and we'd have to ask the physicists. But there is something about inquiry that would make it hard for us to accept this, I think. One goal that regulates inquiry is to find an account that unifies a vast range of phenomena. The more a scientific...

The following comment has been kindly sent in by Professor Kannan Jagannathan (Department of Physics, Amherst College): "The best evidence we have for the isotropy andhomogeneity of space leads cosmologists to hold that the universe hasno center and no periphery. If the universe is infinite now, it was soat the Big Bang, and the bang occurred everywhere (in such a case, thedensity of the universe would have been infinite at BB); if theuniverse is finite (and unbounded) now, it was probably point-like atBB, but it is not to be thought of as embedded in some larger space. That was all there was as far as space was concerned; it was'everywhere' then, and is everywhere now. In the standard model of cosmology, as well as inmost variants of it, the initial rate of increase of the scaleparameter (crudely, the radius of the universe, or the rate ofexpansion of space) would have been bigger, perhaps much bigger, thanthe speed of light. The combination of these two points would suggestthat if...

I think most scientists would reject an assumption in your question — that they believe the Universe needs to be one way or the other. Theories in science do not say how matters must be, they describe how they are .As to why scientists think the Universe does have a beginning, well,presumably it's because that hypothesis best fits the availableastronomical data. If you want the details, talk to yourlocal physicist.