The universe is expanding we are told. Not just that, but the expansion is increasing, meaning its getting bigger at a faster rate now than it was getting bigger before. There’s no set chart of the history of the relative expansion and, of course, even if there was, the time scale would also have to be relative, and it would probably still be wrong, even if the current expansion rate were correct, which it isn’t.
First, the universe isn’t expanding. The shape is just changing. 3D space is getting bigger. MD space is getting smaller. That is, if you think of MD as warped or curved (again, fun to think of what it curves into) then the shape of the universe is getting more 3D and less warped. Because all the energy (and mass which is just another way of saying and being energy) is getting more spread out in 3D space and it is a hall mark of energy and matter that the closer together they are, the more they warp MD space and the further apart they are, the less they warp MD space. So the universe is contracting as well as expanding depending on how you think of it.
We’re 3D creatures. Well, we’re also a bit 4D, but we’re not aware of, nor are our senses designed to detect, nor our brains well imagine 4Dness.
There’s also the problem with the Hubble Constant, discussed elsewhere in this series. In fact, one of the ways we could measure the past amount of curvature (at least average curvature between us and the things that produced the light we see from very far away, is to reproduce Hubble’s work, but instead of using a 3D laboratory legend, we apply a 4D legend.
Here is where, customarily, we should insert a relatively 2D analogy. Imagine the light from a distant star throws a photon toward where we would wind up being now. It’s moving. We’re moving, both in relation to each other and to some universal center point. The longer the light takes to get to us, the bumpier, on average, and therefore longer it’s path would be. Like a wide receiver on a flag route looking back at a ball thrown by a moving Tom Brady who’s running up a hill, and we’re running down a hill. Or some such. Make up your own. The point is, some of the apparent curvature (which we read as wavelength shift) is accounted for by the movement. Some of it is accounted for by the change in z coordinate (really omega, remember?).
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