One theory is that the universe came from nothing. i.e. perhaps bubble-universes collided, as in a bubble bath, and gave birth to the universe. Or perhaps the big bang was created by a bubble-universe which split into two universes. The universe does seem to be compatible with nothing.
A universe that came from nothing in the big bang will disappear into nothing at the big crunch. Its glorious few zillion years of existence not even a memory.
First of all, the Big Bang wasn't very big. Second of all, there was no bang. Third, Big Bang Theory doesn't tell you what banged, when it banged, how it banged. It just said it did bang. So the Big Bang theory in some sense is a total misnomer.
In the popular imagination, the Big Bang is a great explosion; at one time there was nothing, then matter erupted into previously empty space. However, the Big Bang is the beginning of spacetime itself, not an event in time.
Modern thinking is that time did not start with the big bang, and that there was a multiverse even before the big bang. In the inflation theory, and in string theory, there were universes before our big bang, and that big bangs are happening all the time. Universes are formed when bubbles collide or fission into smaller bubles.
We need a theory that goes before the Big Bang, and that's String Theory. String Theory says that perhaps two universes collided to create our universe, or maybe our universe is butted from another universe leaving an umbilical cord. Well, that umbilical cord is called a wormhole.
There is a world of created beings - living things, animals, entelechies, and souls - in the least part of matter.... Thus there is nothing waste, nothing sterile, nothing dead in the universe; no chaos, no confusions, save in appearance.
Earlier theories ... were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past. [Coining the "big bang" expression.]
There is no explanation in the Big Bang theory for the seemingly fortuitous fact that the density of matter has just the right value for the evolution of a benign, life supporting universe.
I was there when Abbe Georges Lemaître first proposed this [Big Bang] theory. ... There is no rational reason to doubt that the universe has existed indefinitely, for an infinite time. .... It is only myth that attempts to say how the universe came to be, either four thousand or twenty billion years ago.
In the popular mind, if Hoyle is remembered it is as the prime mover of the discredited Steady State theory of the universe. "Everybody knows" that the rival Big Bang theory won the battle of the cosmologies, but few (not even astronomers) appreciate that the mathematical formalism of the now-favoured version of Big Bang, called inflation, is identical to Hoyle's version of the Steady State model.
Despite its name, the big bang theory is not really a theory of a bang at all. It is really only a theory of the aftermath of a bang.
Big bang cosmology is probably as widely believed as has been any theory of the universe in the history of Western civilization. It rests, however, on many untested, and in some cases untestable, assumptions. Indeed, big bang cosmology has become a bandwagon of thought that reflects faith as much as objective truth.
But what about the End of the Universe? We'll miss the big moment." I've seen it. It's rubbish," said Zaphod,"nothing but a gnab gib." A what?" Opposite of a big bang. Come on, let's get zappy.
The predominant theory of the origin of the universe is the Big Bang.
One can imagine that God created the universe at literally any time in the past. On the other hand, if the universe is expanding, there may be physical reasons why there had to be a beginning. One could imagine that God created the universe at the instant of the big bang, or even afterwards in just such a way as to make it look as though there had been a big bang, but it would be meaningless to suppose that it was created before the big bang. An expanding universe does not preclude a creator, but it does place limits on when he might have carried out his job!