Let’s assume that the space-time fabric is situated within our entire closed universe and matter is scattered throughout like small insects trapped on a giant spider web. And let’s also assume that the space-time fabric along with the matter is in constant motion, either accelerating because of gravity since they are the same thing (Einstein’s principle of equivalence), or decelerating because of entropy, or shrinking because of dark energy, which quite possibly may be found in the quantum world.
So, finally let’s assume that dark energy is scattered about everywhere in the universe, fighting to overcome the original expansion from the Big Bang and matter and dark matter’s gravitational attraction in an effort to pull everything in back on itself to finally collapse into a Big Crunch. And mathematics tells us that dark energy has about three times as much force as dark matter and all visible matter, so shrinking may well be the strongest force in the universe.
From our perspective, the matter probably would appear to be expanding at increasing speeds. Yet, if the fabric were alternating back and forth between expanding and contracting, we might not be able to recognize the difference between expansion and contraction from our perspective. It might look exactly the same to us on the planet earth.
The matter in the universe would warp the space-time fabric and perhaps, vice-versa, but we would not detect these variations from our perspective. So, what can we surmise from our perspective?
Let’s again assume that the Big Bang was the start of expansion of the space-time fabric when all matter was very close together and should have slowed down time. As the space-time fabric expanded, it would have also expanded the distance between mass in the universe, thus causing time to speed up. Let’s assume that we would not detect this time difference, just as we would not detect it in a spaceship traveling toward Mars.
So depending on our position and speed, time can appear to move faster or slower to us relative to others in a different part of space-time. The phenomenon is called “gravitational time dilation.” In a nutshell, it just means time moves slower as gravity increases.
A time reversal may simply be caused when the expansion away from masses becomes a contraction back to an increase in gravity from the narrowing of the distance between the matter in the universe. Time would initially move faster as everything expanded, but would move slower as everything contracted.
Again, we could not detect this time reversal or the increase or decrease in time. However, we could see the effect of time going backwards by examining ancient galaxies, whose light passed by us billions of years ago. When we can actually see those galaxies which existed billions of years ago, it is only because we are in a time reversal headed back toward the Big Bang, which will be more aptly named the “Big Crunch” for our future. Otherwise, we could not see the sight of these old galaxies, which would have zipped by at the speed of light never to be seen again. Just count your lucky stars that you cannot see the Big Bang… yet.