From what I gather, it can get so hot, that it becomes cold(1 theory), expelled energy. It goes full cycle and falls off so fast, but then the only time its been that hot is in the beginning, when it took 300M yrs. to cool off enough to make the 1st atom. Before the big bang it had to be cooler, though in some hot solid plasma phase but all in one singular point. According to theory...
If light "red shifts" so far in its wave length we may not be able to see it anymore as it flattens or becomes a veryyyy long wave length. While I find wiki a decent source, I don't count on it for solid 100% fact, I rather goto the source as it were. As for tired, it probably more probable that dust and distance and all interference can cause measurements to be off, to include if looking at bent light, but yeah a few kicked(collision ejected) protons would over time be lost.. Bent light(gravitational lensing) can lead to light travelling from distances that you're really aren't looking at the straight-line source. Something like looking at light within "fiber optics" being bent to go around corners. But the big bang theory seems not to support tired light as it stands as red shift is more about galaxies traveling away from us.
Yeah it's still magic. As i stated before from our point in the universe to come to some theories and conclusion is amazing to me. I guess we can interpret the observational knowledge pretty decently.
=== Willy brain fart ===
Which up to now has allowed me to think of mechanisms on the universal scale in my thinking. It's been offered that the universe is all part of a lattice network. That can be very possible as i see the forces of the universe push and pull on huge universe scale. Basically, i see the forces whatever they maybe causing, "pressure ridges" in turn to seen as huge blocks or bubbles. Think of soap bubbles against each other of various sizes, etc., but linked as a lattice that can be seen. All the touching of bubbles as a ridge or boundary from all forces acting upon it. If the universal lattice is real, then its only takes the huge qualitative forces to build it. It's something akin of not seeing the forest because of the trees. If possible then the "connection" to dark energy is that any new bubble pushes on the next bubble causing it to move. Not like billiard balls bouncing, but like a new person in line pushing on person in front, a huge chain reaction. These pushing events are based on time and space events that never get displaced as nothing is lost, it has to makes room for it to exist. Expansion is thus done. Dark matter maybe the substance(best I can think of) of these pressure ridges, it is NOT matter in the true sense but an effect. Which may explain why galaxies don't fly apart, it's a bubble rubbing against another bubble. It all falls into place. ------Willy