This has been bugging me ever since I read ‘A Brief History of Time’. If the universe was very, very small at some point (the Cosmic Egg) would not it have been wholely within its Swartzchild radius - i.e. would it have been a Black Hole? If so, has it since expanded outside its Swartzchild radius (which should be impossible), or are we and all around us still living inside a universe-sized black hole?
Universe-sized black hole is possible, I believe, since no information can travel out of the universe. IANAP.
A black hole has a quantum singularity.
The pre-Big-Bang universe was also a quantum singularity.
However, a black hole’s Swartschild Radius is a function of space, time, and the speed of light, three quantities which did not exist before the Big Bang.
I’ve often wondered about this as well. Enola Straight, it’s not about before the big bang. 10^-20 seconds after the big bang (or some other ridiculously small number) the entire universe would’ve been within the Swartzchild radius of all that mass-energy. So how was it possible for it to keep expanding?
-b
The simple answer is that it is not wise to enquire too deeply into some things. More complicated answers might be that gravity fuctioned differently (if at all) at that time, or that the “inflation field”, whatever that was, changed the size of the Schwartschild radius. Furthermore, it is conceivable that the Universe is, in fact, a black hole: Neglecting [symbol]L[/symbol], the condition for this turns out to be the same as the condition for a closed (Big Crunch) universe.
Enola Straight has the right idea.
The universe is all there is. It is not “inside” anything else, never was, never will be. (In terms of our laws of physics.) You can’t draw a circle/sphere around it.
Going back to the overused and probably not appropriate balloon analogy. Try drawing a line on a balloon that completely encloses the balloon. While the balloon can be enclosed in a larger sphere, that is completely outside our physical realm and not part of the laws of gravity.
(And then one can also argue, since the balloon analogy is a Bad Idea, that the universe was [maybe] born infinite and never enclosable in anything finite in any set of dimensions.)
And then …
For a subset of the universe back when: Energy does leak out of black holes. If you’ve read Hawkings you know about this. The “hotter” the black hole, the greater the leakage. Needless to say, the early universe was hot.
Also, gravity didn’t exist initially. The basic particles with their associated forces took “some time” to form.
And then there are some really weird things to think about. The Schwartschild radius is for objects going “merely” the speed of light. Very far off galaxies from us are actually receding at a speed greater than the speed of light. (We can’t see them of course, never will.) Ask your physics prof. about this (and kiss that letter of recommendation goodbye).