in physics, an explosion involves matter moving outwards through space relative to a center point (or area) of origin. The big bang isn't that because the expansion is not caused by matter moving outwards through space but rather the space itself expanding. And nothing is continuously moving outwards relative to a center point of origin because there is no center to the universe. So all that makes the concept of the big bang a completely different concept from that of an explosion. The two are unrelated. But you still often here TV presenters and even some scientists, who should really know better, erroneously referring to it as "an explosion", which is really annoying.
Originally posted by whodey Shouldn't it be the Big "non-Bang" then?
Correct. The name "big bang" was made by those that wanted to ridicule the theory by the moronic straw man misrepresentation of it being just one big absurd "big bang". But it is not a "bang" at all and thus the "big bang" is a misnomer. Unfortunately, as so often happens, it is the misnomer name that stuck.
Also of note is the fact that it is not known whether or not the universe is finite. If the universe is infinite (spatially) then the concept of the universe going from a single point to a massive size isn't correct either. If it is infinite then it was always infinite. Mind-bending.
If the universe is finite, it is also incorrect to think of it as a sphere in some larger setting. It isn't. There is no 'outside', nor is it spherical.
All we really know is that the universe was once very dense. We don't know much about what came before as it is what is called a singularity where the ordinary laws of physics do not apply.
As with quantum mechanics we often try to draw analogies or visualize things and then forget that we are using analogies and start to try to impose the analogy on reality which is not an exact match. People often get confused about whether or not a photon (or other fundamental particle) is an object (miniature marble) or a wave. The reality is that it is neither. A photon can be particle-like or wave-like depending on the circumstances, but it is never really 'a particle' or 'a wave'. It is surprisingly hard to accept this and to keep it in mind at all times and our brains keep trying to drag it back to one or the other.