Posted by: Jack | May 7, 2007

Impossibly Big Bang

I’m just finishing up Neil DeGrasse Tyson’s book entitled Death by Black Hole and Other Cosmic Quandaries and have greatly enjoyed it thus far. I mentioned in a previous post that within this book I found a description of the beginning of universe which seemed to violate the fundamental physical limit that is the speed of light. In the final chapters, black holes are becoming a more common subject matter and it was during these most recent readings that I was reminded of a paradox that I found years ago when learning about the big bang theory.

Again I have no education in astrophysics so I’m fairly certain that I’m the one who has made the mistake, but I can’t find the error in my logic. As I understand them, black holes are concentrations of matter which are massive enough such that the gravity field created is so strong that the escape velocity exceeds the speed of light. Since nothing, including light, exceeds the speed of light, nothing can escape the black hole. This all seems reasonable enough.

Now lets start at the instant of the big bang. All the mass of the entire universe existed in a singularity. If their is enough mass in the universe today to have numerous black holes cruising around, then it would seem that all the mass of the entire universe existing in a single point would certainly be dense enough and massive enough to be a black hole in itself. So if the escape velocity of this initial black hole far exceeds the speed of light and in fact, exceeds the escape velocity of any gravitational field which has ever existed, how could anything have ever escaped? It goes without saying that the big bang would have been an unimaginably energetic explosion but if the speed of light truly is a physical limit, no explosion could ever accelerate anything past the speed of light.

I’m assuming that there is a connection between this apparent paradox and the one I mentioned previously since both situations seem to claim that things can travel faster than the speed of light. But basing my reasoning on the claim that nothing can travel faster than the speed of light I fail to see a valid explanation for either.

I may just have to write a letter to Neil.


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