The esteemed Mr. Alan Gouth is telling us that the universe expanded at a very high rate, to a factor of 10^78 of its volume, in the time period of 10^-36 to 10^-32 after the Big Bang. He called this, inflation.
Does this explain why we can observe a galaxy at 13.2 bly away - call it galaxy G - when the universe is supposed to be 13.7 by old?
When light left galaxy G 13.2 by ago, the space that the Earth now occupies did not exist, right?
So, is the initial inflation and the later expansion of the universe much faster than the speed of light, so that masses that are created within the universe can be so far away from each other that it takes 13.2 bly for light to go from one mass to an other, like from galaxy G to the Earth?
Galaxies did not exist until long after the time of inflation. The fact that the size of the observable Universe is greater than the age of the Universe times c can be explained by any expansion at all, not necessarily the hyperfast expansion of inflation.
By way of analogy, picture an ant crawling on a string, at constant speed (let’s call it the Speed of Ant). If he sets out from Point A at one time, and arrives at Point B at some later time, then we can find the distance from Point A to Point B just by multiplying that time by the Speed of Ant. But now, suppose that the string is replaced by a rubber band that’s getting stretched, such that Point A and Point B are getting further apart: Now, the simple formula of distance = time*speed isn’t good any more, since in the time that the ant has been crawling, Point A has also been getting further away.
This is all oversimplified, of course. In the real world, it’s not even clear how to define distances on the cosmological scale: There are several different definitions of distance, relevant for different purposes, which all agree on small scales but disagree on large scales. That’s the gist of it, though.
So the expansion rate must be greater than c and we can assume that there is no reason for that rate to slow down or speed up during the life of the universe - excluding the period of inflation.
Using the rubber band analogy, the rubber molecules are stretching out and the rubber band becomes longer. When space expands it seems that it does not drag mass with it at the atomic level, meaning, it doesn’t stretch out atoms or subatomic particles. Does that mean that the 3 dimensions of space are an underlying structure independent of the mass or energy fields that exist in it?
The expansion of space cannot be compared to the speed of light: One might as well ask whether you’re taller than the speed of light. The expansion of space has units of frequency, not speed, and for any given rate of expansion (no matter how fast or slow), there will be some distance beyond which the effective speed is c.
It does, but at the atomic scale the movement is very tiny and it’s completely overwhelmed by the attractive force between the particles. Even at the scale of an individual galaxy the current rate of expansion is overcome by gravity. You have to look at the relative movement of galactic clusters for it to have a significant effect.
It’s difficult to talk about something like “a change in the speed of light”, since you’d have to specify a change relative to what, and then you have to ask what it is that’s really changing. Ultimately, the only things that you can definitively say change are dimensionless numbers. For instance, there’s a constant called the Fine Structure Constant, which is defined as k[sub]e[/sub]e[sup]2[/sup]/[del]h[/del]c , and which has a value of approximately 1/137. Note that I didn’t specify any units, there: It doesn’t have any. If there were some evidence (as some folks have claimed to have found, though even the folks who found it agree that the evidence is extremely weak) that the fine structure “constant” has changed over the lifespan of the Universe, that could be interpreted as meaning that c has changed, but it could also be interpreted as meaning that e (the charge of the electron) has changed. Ultimately, all you would be able to say for sure would be that the fine structure constant had changed.
