This thread is pretty cute. I'll just interrupt the shenanigans for a moment to respond to something...
On that note, I think my deeply rooted insecurities with the BBT have come mostly from an incomplete understanding of it, especially with the idea that it posits a definite start but no end. It seems to be a case of something Wigner discussed, the "Unreasonable Effectiveness of Mathematics in the Sciences".
For example, here's a holistic argument for its flaws. In the big bang theory, space itself must have stopped expanding all over the sphere in a completely uniform manner.
But what happens if quantum uncertainty stops a pocket of space from expanding as fast? It is pinched off into a bubble on all sides. Inside, space keeps expanding. A universe is born.
The big bang theory, in principle, predicts that an infinite amount of universes are formed. And inside them, everything that can happen happens. The big bang theory predicts everything, and therefore nothing.
I'm bracing myself for a physicist to correct me. (I would love for that to happen, by the way)
I'm no physicist, but I've got enough of a working grasp on the theory to be able to answer some of this.
The BBT does lack a definite end point, but that doesn't really mean much because it actually doesn't give a definite start either; it doesn't actually explain where the universe started, it just says "first there was everything in one infinitesimal point, then it expanded." Just as it does not pretend to be able to explain where everything came from, it also doesn't pretend to know for certain where everything will end up. However, there have been a lot of attempts at end times explanations that use its information without officially becoming part of the theory. The most popular one is the heat death of the universe, which says that the universe will keep on expanding and entropy will keep on increasing to the point that the energy in the universe is spread so thin that nothing much happens. And then it'll keep on expanding and spread the energy even thinner. Not much of an end in the way of "everything explodes or disappears," but it would be a definite end as far as living things and thermodynamic processes of all kinds are concerned.
The universe didn't expand in a uniform matter, or it's not currently doing so at least. I don't think the Big Bang Theory ever proposed a sphere either, but I could be wrong.
Back in 2008 some researchers found that things seem to be expanding in a non-uniform manner, and from what I can find it seems like this has been confirmed and accepted at large. Scientists also don't think it's spherical in shape. There are all sorts of theories, but the most popular one is that it's sort of flat (relatively thin from "top" to "bottom" but expanding infinitely out to the "sides" like some kind of cosmic pancake). A couple other shapes that fit the current observations are a dodecahedron or
some sort of horn thing. I won't even pretend to understand the complex math that explains why those shapes are the most plausible ones.
As for other universes, eh, there are plenty of hypotheses out there that suggest as much. Big names in science ranging from Stephen Hawking to Neil deGrasse Tyson support various versions of such ideas. The only problem is that such things are, as far as we can tell, not falsifiable and therefore not really scientific notions. The Big Bang Theory does not actually predict anything of the sort, by the way; it simply seeks to explain what went down and is still going down in
our universe. No part of it says "there absolutely are other universes" because it's strictly concerned with this one. Multiverse hypotheses do nothing to discredit the Big Bang Theory because they're tangential side things, not part of the main attraction. It has proven predictive power, the big case being the prediction of cosmic microwave background radiation a few decades before it was discovered. It doesn't predict everything, but what it does predict has been pretty spot on, which is why it's currently the best model of how the universe got from point A to now and what is likely to happen in the future on the large scale. It could always get dethroned, but I don't think multiverse shenanigans will be the cause.
Okay, now back to the regularly scheduled nonsense, I suppose.
