This is a classic question which so many ask, but never find an answer. I’m not saying I’ve found an answer, not at all – after all, this is just my theory.
It is widely accepted that the universe came into existence via the Big Bang, and has been expanding since. We have empirical evidence that this is most likely the case: redshift in distant galaxies and quasars, cosmic microwave background radiation, the abundance of primordial elements etc. So, typical to human nature, we arrive at the question: what is it expanding into? If the universe is absolutely everything that exists, how can it be expanding into anything at all? Here’s my idea:
The universe is expanding into itself. Hear me out:
Imagining the universe as an object is not applicable; it is not a ‘thing’ (since space, time and energy/matter only exist within the universe). But for this analogy, visualise it as a zero-dimensional sphere; that is, a sphere with no actual dimensions or ‘size’ (it can’t, because, as far as we aware, it is everything). The ‘space’ (i.e. the universe we observe) (not the objects inside it, however) inside the sphere is constantly subject to changing size, but this ‘sphere’ is not. Imagine the universe as the Tardis from Doctor Who – it never changes ‘size’, but the space within it can and, in this example, does.
So what we get is a universe that is contracting from a ‘possibility space’, in a manner that cannot be fully understood by the human mind. I’m going to use this brilliant picture I crafted in MS Paint to help me explain this idea:
The sphere on the far right depicts the universe in, say, a few billion years. The red arrows indicate the contraction from the black line (the possibility space). The black line is not a border, or ‘the edge of the universe’ – it’s in place to aid in this analogy. As you can see, in the middle of the right sphere is the universe as it is today, but smaller. It hasn’t actually got smaller, however; it’s just making more space. If the universe is infinite (which I believe it is) then of course it will never get smaller – more room just keeps being made around it. I drew another picture to depict the universe in an additional few billion years:
As you can see, more space has been made due to this cosmic contraction. This pattern will continue to happen until the (possible) end of the universe. This contraction appears to us as expansion due to our perspective; as we are contracted, more space becomes available. Because we don’t change in size, however, it appears that space is moving away from us. Imagine this scenario as mental aid:
You are walking down the street: now of course, you are moving down the road; you pass the streetlights, mail boxes, bins etc. You move through the universe. But what if you were actually stationary, and the streetlights, mail boxes, bins – the universe – moved around you? It would still appear, and make sense, that you were moving through the universe.
Thanks for reading! Please comment if you have any questions, counters or anything of a similar manner. If you are wondering about how the universe started – why there is this sphere in the first place – please read my post on my secondary blog: Bound, But Infinite. You can find it here: http://boundbutinfinite.wordpress.com/2013/05/12/original-idea-sims-the-universe-has-neither-beginning-nor-end-a-zero-and-ten-dimensional-infinitely-cycling-existence