In 1929, the astronomer Hubble noted that all the stars and galaxies were speeding away from us so our universe is expanding, and is doing so everywhere at once, not just at its edges. But if it is expanding out, why is light from just after the big bang still all around us today, as the cosmic microwave background? If space is expanding, what is it expanding into? And if space is something not nothing, what creates new space? Current physics can’t answer these questions. but space as a hypersphere surface expanding (2.2.5) can.
A hypersphere surface has three dimensions like our space, but no edges like a balloon surface, so it expands everywhere at once. But unlike a balloon, it is inside a larger bulk, so it is really a bubble. Space as a balloon surface expanding puts us on its outside, but what then is it expanding into? Space as the surface of a bubble within a larger bulk answers this question, but puts us on the inside of the surface (Figure 2.11).
It follows that space, to us the ultimate container, is itself contained. A bubble in a liquid expands everywhere at once but unlike a balloon, its surface increases based on what is around it, not itself. A bubble expanding has no center or edge, so waves vibrating upon it wrap around to end up everywhere. Likewise, light from long ago, cooled by expansion, is still all around us, as cosmic microwave radiation. This model answers questions like:
- What is space expanding into? It is expanding into the quantum reality around it.
- Does our universe end? No, a bubble surface has no end.
- Where is space expanding? Everywhere, just as a bubble surface does.
- What creates new space? Quantum reality creates new space.
- Are we expanding too? No, objects on a sphere don’t expand as the bubble does.
The next chapter on light takes space to be the surface that light vibrates on, even when space is empty.