I touched on the subject of time yesterday and lets continue that today as well. Time has always been thought of as a river. It flows. And the mental of time as a river is appropriate example to use for our cause. Everyone has seen rivers , either in real life or from TV , so it shouldn’t be a mystery.

So can a river flow up or down? Yes. But how does it flow usually? Usually , it flows one way only , down stream. Likewise , the physics of our universe doesn’t prevent time from only moving forward , it can also flow backward but it is never observed in real life. Why is that so? We can look at it as the river example above to understand that although time can travel both forward and backward , it will only travel one way , forward.

So does it mean time travel is impossible? Again , no. It is possible from every theories that we have discovered but why are we not seeing any time travelers from future? Think of events such as your parents meeting for the first time , can we go back in time to see them at that instance? No.

Imagine a river , with a large rock in the middle. A school of fishes swam past by. Can these fishes be brought back to the place just before the rock? Yes. But can the exact scenario be repeated? No. There will be different interactions , or maybe one of the fishes were caught by a predator. You cannot repeat the same scenario even though the same school of fish , the same river , the same rock and so on. You can repeat the experiment hundreds of times but each time , the outcome will be different.

So , does that answer the questions such as where are the time travelers from future and why are not messing with us? They are there but their past is unlike our future as at each moment , the interactions between molecules are random means that the outcomes are also random.

We can predict which way the fishes will swim but we cannot be certain that which fish will be the first or the last. Yes , you can go back in time and prevent your parents from ever meeting but that simply means there will be no You in this future , not the future that you came from. Likewise , you cannot , say go back in time to kill Hitler to prevent World War 2 because World War 2 has not happened yet in future of your current time.

Hope it clears why time travel is both possible and yet nobody from the future has ever come back to mess with us.

The end.