Yeah, that explains my confusion. There was some Sci Fi story (I think part of the Ender's Game series) where they would travel at close to the speed of light in order to slow down, so somebody stayed young even though hundreds of years passed on Earth. Knowing that it's an equal and opposite perception and that time isn't actually affected helps make things make a lot more sense.
One way to think of this is, several hours later, they're a hundred light years away, but only a few seconds have passed on Earth. Earth starts chasing them at a similarly obscene velocity a few of Earth's hours later. Earth will catch up to them in several hours from Earth's frame - but will take centuries from the perspective of the people in the ship for Earth to reach them.
Naturally, at that point they'll have traveled a ridiculous distance from Earth's original frame of reference.
So why doesn't the world age slower (ie those on it younger than you) to the Astronaut that returned as it was "moving at 0.9999" the speed of light for a period of X compared to the star-ship traveler ?
The one who undergoes the actual acceleration is the one that experiences the time dilation, generally. The Astronaut accelerated to .9999c, decelerated to 0, than accelerated back.
Is it due to "relative speed to the center of the universe", ie the one"reference point" that is universal?
There is no such point. There can be no such point, as parts of the Universe are receding from us faster than light. You can make the math work by declaring the IGM to be a 'special frame', but that space is still expanding, and for our purposes, it isn't necessary to consider. That 'special frame' is no longer a single point, it's an abstraction of the Universe in its entirety.
Now if everything is rotating, and you go in the opposite direction to everything else, compared to the center of the universe your at te same speed. But you may be traveling at 0.5 c or something (compared to everything else around you) then what ?
Again, there is no such thing as the Universe having a 'center', except for one that is omnipresent.
It has to do with the "arrow of time", each quantum thing has its own "arrow of time" the less entangled you are with other things the more ind-pendant that arrow is (ie quantum things happen instantly going forward and backwards in time) that's when they are are only entangled with each other and nothing ELSE. What your entangled with you SHARE an arrow of time with.
The 'arrow of time' merely defines our perception of time, in that entropy represents an irreversible process and thus we can conceive of a 'past' and a 'future'. It is not, in and of itself, time.
I think you've been reading stuff that has confused more than enlightened you. : /
This MAY be true for different parts of the universe, or very differnt perspectives (Real in their own regard)
they may not agree on ANYTHING.
All frames of reference, after working the proper math, will agree on what is happening to all other frames of reference, at least within the observable Universe to some suitably obscene precision. While e.g. a quasar moving away from us at .99 of c seems to be moving forward in time rather slowly, we know that a sapient observer living 'now' in said quasar will see the Milky Way much the same way (if our rather uneventful galaxy can be noticed so easily from such a distance, anyway - just pretend they have a better funded space program with bigger telescopes >_>).
While we do permit the idea that e.g. the 'Universal constants' may be able to 'change', e.g. the fine structure constant might have changed on the order of something like one part per billion or less over aeons - it's of somewhat limited relevance to this discussion. For one, we can observe that and take it into account, if it exists, but for two, even on the observable large-scale structure of the Universe, these variations, if they exist, are extremely tiny.