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[Stanley Huang]

If time can flow backward, can we change the past?

I heard professors talking about this question, and because this question may not be easy.

If we can change the past, can we stop Hitler?

And it may be strange that if a person can change the past, then are we going to say what happened before happened, if we changed history?

So that professor I saw in TV said: "If we can change the past, what happened already happened just like what Hitler had done already happened. Because it will be strange that if we change the past, what already happened disappeared. But what will happen is that if we can change the past, we will be knocked into a parallel universe."

To me, what he is saying is this: What Hitler did happen already and we cannot change that. However, if we can change the past, then, there are more than one universe, where one universe is the history of what happened in the past while another universe is the universe that shows the past that we changed.

If it is like this, then, it may not be strange, that even if we can change the past, what Hitler did happen but at the same time, there is also another universe that will record the past we changed?

Ok? Do you have any word to add?

[Eckhart Aurelius Hughes]

Time would need to do more than flow backwards. One would need to time-travel. 'Rewinding' in a deterministic universe is not enough to alter history because when you 'press play' again everything will happen the same exact way again. Indeed, in a deterministic universe time is an illusion or at least a matter of perception for non-omniscient beings (and one only needs to be omniscient in regards to one frame, one moment of time, in a deterministic universe to be omniscient about all). Time travel that does not allow for determinism involves making time rewind for some and not for others, which leaves the universe in a state it was never in before from which things will play out differently. This leads not really to time flowing backwards but rather to closed time-like loops, which entail all sorts of contradictions and paradoxes and which at least in most instances seem to violate known laws of physics. Hence Stephen Hawking's chronology protection conjecture.

[Stanley Huang]

Scott said: "Time would need to do more than flow backwards. One would need to time-travel. 'Rewinding' in a deterministic universe is not enough to alter history because when you 'press play' again everything will happen the same exact way again."

That is only the original universe, the universe that records the past and the universe where time flows forward, from the past to the present and then to the future.

But I will use pumps to make it more simple as illustration. You see many pumps. One pump is one universe. Now, if in a factory that there are many pumps. So the water flowing in one pump shows that original universe where time flows forward from the past to the present and then towards the future.

But as water flows in that pump of the normal universe of time progressing, the water then flows into another different pump and this pump will lead the water to travel back to the original position of where it begins. Once the water travels back to where it begins, the water then enters into another new pump, where the water moves in a totally new direction that it has never been before.

Using this illustration, which is more simple for you, then, that if time flows backward, still, you can change the past while not violating the past the happened, and at the same time, having more than one universe to records different time flows and different things happening in different direction.

Is the above illustration ok?

[Simply Wee]

We can only act in time, outside time, everything changes with or without us. If we could somehow go back, all that was there would no longer be. Time is like a river, reality drifts with time. Moments, brought together, with time. I guess.

[Stanley Huang]

We can also change time. Because your thinking is like Newton, where you think time determines how a thing flows. But Einstein questioned Newton, by saying that there is exception. And an object can change time if it speeds up. So objects can change the speed of time and even the direction of time.

So time is no longer an independent entity determining things, rather, object itself can determine the direction of time flow.

But whatever happened happened. So if Hitler existed, he existed, we cannot change that.

But if we can change the past, what will happen is that we create a new history from now.

What this is is that from now, we flow back to the past and then change the history and then, we create a new direction of time, which a totally new universe is created different to this universe.

So I am saying, if this universe is like a pipe, we can flow through a pipe or tunnel to another pipe which is the past, and from the past, we change what is happened and then, we enter into a new pipe or tunnel, into a totally new universe.

For this to happen, the present moment must be able to meet the past, where two different points of time meet at one stage, and then, flowing into a totally new direction of time, that is not forward and not backward.

Where time can flow to the east, west, north, south or in any other direction, if time is able to have a shape, flowing in a curved shape.

But there must be a universal time to record the individual time that is able to flow backward or in any other direction.

So my writing about time is this: The universal time must go forward, while the individual time can flow backward or to any other direction such as east, west, north or south.

There are many individual times, such as the time in Tokyo, or the time in London, or the time in New York, or the time in Mars, but there is only one universal time, and this universal time must go forward and this time records all of the individual times, where some times flow backward, while other times flow to the east, or in any other direction.