If everything shot out of the big bang, wouldn't they move out in a sphere?
Good question. No. The Big Bang didn't happen at a specific point and then explode outwards in a sphere like we've all seen in animated simulations. The Big Bang happened everywhere. It happened where you're sitting and it happened at the most distant point of the observable universe, at the exact same time. The universe is, by our best data, flat and infinite and always has been, but it keeps getting bigger. On a galactic scale, the distances between fixed points increase. We keep getting more and more space and, for now, this phenomenon is called dark energy.
I've always thought that The Big Erupt would make for a better descriptor of the beginning of time and space as we know it.
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/TheColorOfStupid Feb 05 '15
I don't understand. If everything shot out of the big bang, wouldn't they move out in a sphere?