What is the beggining of space time?

[phy_freak]

was it that singularity? what makes us so sure? what does GR predict? please be as detailed as you can and take your time if you have good information even if there are any equations. thanks in advance !

 

[Naty1]

was it that singularity?

yes.


what makes us so sure?

it's generally accepted...but no one is sure...maybe, for example, time is eternal...
big bang is a favorite, little bang also a possibility...Strictly speaking, the big bang model has very little to say about the big bang itself. It describes what happened afterward.


what does GR predict?

GR and QM breakdown at such singularities as big bang and black holes...useful but not a final conclusive answer. But GR posits that space and time are NOT fixed, they change and for some reason gravity is a consequence of mass, energy and pressure...says nothing about which came first.

Ultimately nobody knows what space and time are nor how they are related. Nor how they relate to matter and energy...all have "mysterious" unexplained origins...

You can read a lot of posts about spacetime on the forms here by searching Ted Jacobsen, Verlinde, Renate Loll, emergent spacetime, for a start...






please be as detailed as you can and take your time if you have good information even if there are any equations. thanks in advance !

 

[bcrowell]

In terms of classical relativity, the reason we can be sure of this is the Hawking singularity theorem: http://en.wikipedia.org/wiki/Penrose–Hawking_singularity_theorems

To check that the theorem applies to our universe, you need some observations. Here's the original paper on that: http://articles.adsabs.harvard.edu/full/1968ApJ...152...25H I believe the analysis in this paper had some holes in it, which were plugged later. More about that here: http://nobelprize.org/nobel_prizes/physics/laureates/2006/smoot-lecture.html I think this is also relevant: G. F. Smoot, M. V. Gorenstein, and R. A. Muller, "Detection of Anisotropy in the Cosmic Blackbody Radiation," Phys. Rev. Lett. 39, 898–901