So I thought up an idea for a universe, that would have an infinite universe, at exactly the critical density (on average), but with some slight fluctuations resulting in inhomogeneity. Also, equal parts matter and antimatter at the start, with high density.

 

So my idea is that the parts of this universe with equal parts matter and antimatter will annihilate and tend to cause expansion, whereas the parts where there is some slight separation of matter and antimatter won't expand so much. The part in between would expand since it would have both matter and antimatter, resulting in total isolation of the matter from its antimatter. The end result would be an infinite number of matter-dominated and antimatter-dominated pieces of universe (very rare though), which themselves would be finite and have slightly more than the critical density, separated by vast expanses of universe slightly below the critical density.

 

My question is, does this contradict anything we know about the universe? I know it rejects the Cosmological Principle, but as far as I know that is just an assumption.

Can you explain the mechanism for how matter and antimatter will annihilate and tend to cause expansion?

Well, I'd expect that areas where there is matter/antimatter annihilation would be of slightly lower density (if there are any nearby areas with less), because the photons would travel faster than the particles and so more leave than arrive, leaving less mass-energy. Basically, it would be hotter than areas with the matter and antimatter separated.

I tried once to create a universe, and failed pathetically.

IMHO you have to begin with more fundamental elements than matter and antimatter.

 

I tried like this:

_Nothing.

Is nothing possible?

Blah blah blah.

Well, I'd expect that areas where there is matter/antimatter annihilation would be of slightly lower density (if there are any nearby areas with less), because the photons would travel faster than the particles and so more leave than arrive, leaving less mass-energy. Basically, it would be hotter than areas with the matter and antimatter separated.

Before the recombination the Universe is thought of as a hot dense plasma which was effectively opaque to radiation, if the photons are not able to travel further than the closest particles then any difference in propagation speed should be tiny. Hotter areas would decompress into cooler areas with lower pressure but compared to the huge expansion rate of space on large scales in this early time period I don't think the difference would change much.

 

IMHO, I think that if there exists a larger pattern in the Universe than what we currently are able to observe and base our understanding of, then there might very well be huge areas with matter separated from huge areas of antimatter, but the voids filled with radiation and empty of matter would not be much greater than the areas filled with matter or antimatter by this mechanism.

Edited December 8, 201015 yr by Spyman