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Q & A: was there a big bang?

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Most recent answer: 07/24/2012
Q:
Why is the big bang looked at as coming from a singularity and not a super massive star, because if the universe started from a super massive supernova that started expansion and created a universal core black hole it would explain why expansion speeds up the further it moves from the gravitational pull of the central black hole. I just think that makes more sense than an undetectable "dark energy".
- Bradley McCoy (age 30)
Pasadena, MD, USA
A:
General Relativity has been subjected to many experimental tests and passed all of them. We have every reason to think that it is correct down to some very small time-distance scale, at which point neither theory nor experiment currently give us much guidance. There's a theorem in GR that the universe must include a naked singularity. Thus we must have something that looks very much like a singularity down to extremely small time-distance scales. The option you want doesn't satisfy the theorem.

At a more mundane level, the picture you give wouldn't reproduce even the simplest qualitative features of the world we see. Yes, if you look at things lined up radially with the "center" and us, the differences in gravity would produce local tidal effects that from our perspective would look like accelerating expansion. However, looking at things tangentially, not radially, separated from us would actual give the opposite effect, completely unlike what we see. There are other problems as well.

The current big bang theory explains not just a few observations but a range of detailed features of the microwave background, the redshifts of galaxies as a function of distance, the form of clumping of the visible matter, etc. Competing theories need to strive for similar completeness.

We start to be able to keep track of things at a period likely to either be the end of rapid cosmic inflation or the aftermath of a higher-dimensional collision. The Planck satellite is currently taking data that should help sort out those possibilities.

Mike W.

(published on 07/24/2012)

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