I have been doing some reading about the start of the universe and some sources would state that the universe started as a singularity. But how does this not clash with the uncertainty principle?


closed as unclear what you're asking by Kyle Kanos, WillO, Yashas, honeste_vivere, Jon Custer Jul 5 '17 at 18:50

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    $\begingroup$ How do you think it does violate it? $\endgroup$ – Kyle Kanos Jul 5 '17 at 10:11
  • $\begingroup$ well if all matter is contained in a small space would't both delta x and delta p be equal to zero? $\endgroup$ – Lucas Meelhuijsen Jul 5 '17 at 10:20
  • $\begingroup$ I quote A.Einstein from The Meaning of Relativity : "The present theory of relativity is based on a division of physical reality into a metric field (gravitation) on the one hand, and into an electromagnetic field and matter on the other hand. In reality space will probably be of a uniform character and the present theory be valid only as a limiting case. For large densities of field and of matter, the field equations and even the field variables which enter into them will have no real significance. " ... $\endgroup$ – Mihai B. Jul 5 '17 at 14:03
  • $\begingroup$ "One may not therefore assume the validity of the equations for very high density of field and of matter, and one may not conclude that the ‘beginning of the expansion’ must mean a singularity in the mathematical sense. All we have to realize is that the equations may not be continued over such regions. This consideration does, however, not alter the fact that the ‘beginning of the world’ really constitutes a beginning, from the point of view of the development of the now existing stars and systems of stars, at which those stars and systems of stars did not yet exist as individual entities." $\endgroup$ – Mihai B. Jul 5 '17 at 14:03
  • $\begingroup$ So this source claims that the beginning wasn't a singularity, recently I found similair things, that it isn't neccasarilly one point just very small, that does seem odd though, like, why that size? $\endgroup$ – Lucas Meelhuijsen Jul 13 '17 at 12:51

Uncertainty principle is a quantum phenomenon, which is not present in general theory of relativity. The singularity of big bang is appearing when you try to describe the evolution of the universe in general theory of relativity. So the relativistic singularity does not violate any quantum laws, simply because no quantum laws are considered.

If you want to consider quantum effects at the big bang, you need to unite general relativity with quantum field theory. This is difficult and not yet completely resolved. It is assumed that such united theory would remove the singularity, because the sigularity is most likely just a failure of general relativity to describe physics at quantum level.

For more information read here.


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