I never got sleep for few days when I was studying 11th standard. I learned time is not same for every one. Time might be ticking slow for me because I am on massive Earth, traveling at incredible speeds through space, where’s an atom entering black hole could have much slow rate of tick, may be some where in void stationary space if there were people watching me on earth and the atom thats near black hole, they could be experiencing ticks much faster as their region is relatively mass less, and their clocks in their hand is stationary to them.

Today we kind of measure time depending on speed of light which we believe is of constant velocity, but velocity of light is based on time, so there is a circular dependency.

In this blog I would like to say how I think this universe keeps track of time. It could be right or wrong.

Time is memory of state transitions

Let’s say that there is universe, and nothing happens in it, then there is no flow of time. Now say all of a sudden universe switches from state S1 to S2

Then if the state S2 and the universe remembers it was in state S1, then we register it as time has passed.

Short Time

Let’s say that there is registry of only few states (or state-transitions) available in this universe, then we say the universe is very young.

If there another state transition takes place, and the memory of it persists,

then we say universe has got bit more older.

Could Time reverse?

Let’s say that the universe has gone from state S1 to S4 as shown below.

Now if there is possibility of universe going back from S4 to S3 by completely forgetting about S4, then we can say time has reversed.

Now if that happens, there is no way of knowing it as there is no memory of S4 in S3, and hence no evidence of time reversal has taken place. May be there is time reversal is happening all the time (nice pun!), and we have no way of knowing it.

Now if time does reverse and universe gots to state S3, then it may or may not take the same path again. The universe may go from S3 to S4, or from S3 to S5 or may be to some other state as shown:

Why Time travel may not be possible?

If universe reverses time we may never be aware of it because sate of the universe includes its memory. Let’s see a scenario as shown in the diagram below

Universe goes from state S1 to S4, then back to S1, in this case S1 knows that it came from S4, so this is the case of cyclic universe. May be as Sir Roger Penrose suggested universe could go to a state where its just another big bang.

Once S1 remembers state of S4, may be that might affect the next state, may be it might not transition to S2 because of randomness, or if the universe is only deterministic, it will only go to S2 and no other state and so on to finally going to S4 and returning back to S1.

In a very deterministic cyclic universe, all that had happened will happen again and all that is going to happen would have happened.

Is there Time?

Time is just the memory of states of universe, that’s it. It’s the remembrance of these states we call time.

Probabilities & Birth of new Universe

It would be interesting to investigate if universe is in state S1, the is the universe is really deterministic? Or it has the chance to take on multiple states as shown below.

If universe can slip into multiple states from current state, then is there is a probability associated with it? Can that probability be measured?

If the universe is in state S1, and it slips into state S4 a special state where there is no memory of S1, then it would look like the birth of a new universe which arose from nothing.

Get the diagrams

You can download the diagrams of this blog here.