At Big Bang

Is it the case that many facts discovered about the working of the universes are not understood by scientists. eg. Clocks moving relative to each other keep different times. Fact - but do scientists understand how this can be? Just prior to BB, the universe was at infinite density - what is "infinite density"? BB came out of absolutely nothing - no time, no space, no matter and no energy - do scientists understand how this could be? And it happened for no reason.
- robert hutchins
Spain

We don't understand much about the start of the Big Bang. It is widely believed that our current description of spacetime (General Relativity) is not a sufficiently general theory to cover this event. The picture you have of there being something like time with a compressed state existing until it starts to Bang is almost certainly wrong. There may be some broader 4-D (or higher dimensional) manifold of which our 4-D universe is just a segment, and for which the extension of our concept of time outside that segment wouldn't make sense.

It might sound like all that's left is pointless speculation, but in fact different ideas about extensions of our spacetime have subtle experimental implications, which are now being tested.

Mike W.

(published on 05/16/2013)