/sci/ - Science & Math

Wouldnt inflation, if correct, prove that FTL is possible?

>>11650874

Let's take this grain-of-sand-sized universe at 10^-32 seconds. A photon emitted on one side of that grain wouldn't have time to get to the other side, not even in 400,000 years. See, although light is fast, those opposite edges of the universe were traveling apart even faster. Another way to say this is that those edges of the universe have always been beyond each other's particle horizons. So those edges shouldn't be in each other's observable universes, not then, not now. This serious issue is called the Horizon Problem And it's a big deal that we need to sort out.

The only way around this problem is somehow have the universe, once upon a time, be small enough so it could easily get all nicely mixed together, and then pow!, blow it up in size much faster than general relativity would normally allow. The theory that describes this is called Inflation. The idea is the universe started subatomic, small enough that it was able to even out its temperature and then enter the state of insane, exponentially accelerating expansion in which it increased in size by a factor of at least 10 to the power of 26. So 100 trillion trillion to something like our grain of sand size at which point it slowed down to its regular expansion rate. But its edges are thrown way out of causal connection. Yet, they look the same because they were once causally connected.

This whole idea fixes our horizon problem. In fact, inflation solves a number of vexing problems with the Big Bang Theory so well, in fact that most cosmologists accept that something like this must have happened even though we don't have any direct evidence for it. There are a number of explanations for how inflation might have happened. And some of them actually call into question our understanding of that very first instant of the Big Bang.