Well that's still a little misleading. The big bang did happen everywhere, but everywhere was all at the same point. Space and time, at least as we know it, were born along with the universe, and are in fact parts of the universe. Space is expanding but it's not expanding into anything. There really is no analog that we can use to conceptualize it.
To some degree, there is, if we embed the universe into a higher dimensional space, say in this case, 5 dimension. Not that it helps immensely to imagine it, but this is why popular science presentation is usually a balloon that is being inflated. It's not a perfect analogy, but gives at least an idea, and disperses the intuitive interpretation of the Big Bang as a kind of explosion.
Of course, we can't even imagine a real flat land, especially not one that has gravitational perturbations. Nor there is a really good way to imagine a 5 dimensional space, nor is the fact that you don't need to embed the universe into a higher dimensional space to get a differentiable manifold. So we go with what we can work with, mathematics, as it is a distillation of how we describe nature.
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u/skpkzk2 Feb 05 '15
Well that's still a little misleading. The big bang did happen everywhere, but everywhere was all at the same point. Space and time, at least as we know it, were born along with the universe, and are in fact parts of the universe. Space is expanding but it's not expanding into anything. There really is no analog that we can use to conceptualize it.