Since I’m making a fool of myself, might as well be thorough and go full moron, the only rep I’m blowing up is mine.
Another favorite thought experiment of mine is about the nature of time. It’s a very stimulating, fascinating concept, time. And I like to think, ignoring rules and pondering every little bit that comes to mind, no matter how wrong they can be. Also, I tackle things in reverse, asking questions like: what would have to be true for us to get this result? The current topic? Time – what would have to be true of time in order to have space expanding slower than we’re currently seeing? And since there’s no rules for thought experiments, I’d like to imagine time as the natural progression of space. If space is expanding, it is expanding into something and that something is time. If I think of time as an extra dimension of space, it’s better if we consider the 3D space a holographic image of a 2D sheet of rubber – I’m just saying this to make it easier to visualize the arrow of time, because it’s convenient and not because of the holographic principle that’s been making waves the last few years. So space without time is static, time can go faster or slower so space can expand faster or slower. What manages that speed of expansion? Like a kid, I’d say mass. The bigger the mass, the slower time flies around it, creating the sort of temporal drag on local space. No, I don’t mean mass influences time – because that would mean objects with big mass would dissapear from time – I just mean mass slows the expansion of localized space. It’s easier if we look at it as if it were a contained system. Local time slows down, local space expands slower – but outside the system space expands in time just like always.
So if time is the dimension in which space expands, it’s easy to make an uneducated guess on what would happen if we measured the galactic color change outside a big clump of localized mass – inside a rather empty part of the universe – it would seem to an outside observer that space is expanding slower – because the drag exerted by mass locally inside a galaxy makes the … aww hell.. Let’s go back to the 2d sheet model. If we have a large piece of rubber with several really heavy stones on it (galaxies, stars, and so on), we could assume it’s the space model without the dimension of time. If we stretch it, those parts of the rubber that have no stones on them would expand faster than those parts covered by the heavy stones. Those stones represent a force slowing the expansion of the rubber. So the point goes, by this analogy, time flows the same but the expansion of space is slower around concentrated pockets of mass. Locally, if we think of time as a dimension, it would appear that time is slower around the mass. Unfortunately, to expand the fabric of space in the time dimension would mean there was a force in that time dimension that generated the expansion – and also that mass, by creating gravity, can only have a localized effect on time. So, in other words, if we’re to measure the speed of galaxies outside a gravitational well we might find their speed is different from what we measured inside the gravitational well.