# How is traveling backward in time possible?

1. Apr 13, 2012

### Bararontok

How is it possible to go back in time when all the matter in the universe cannot be reverted to its original states once the matter has experienced changes in its states? Once all matter has experienced changes in state, the previous states of all matter are already considered non-existent, so how is it possible to go back to a state of the universe that no longer exists?

2. Apr 13, 2012

### Staff: Mentor

As far as we know it is not possible.

3. Apr 13, 2012

### phinds

The conceit of most "going back in time" concepts is that time is a continuum that still exists and that one can JUMP backwards into somehow, as opposed to a backwards regression of events. This totally defies all known physics and is utter rubbish.

4. Apr 14, 2012

### bobc2

Hi phinds, I assume it's the "block time" concept we were discussing in another thread that you are here identifying as rubish. That other thread is the one that reviews Paul Davies's book "About Time" that has quite a bit to say about block time (he sometimes calls it timescape). One of his statements says that most physicists (including Einstein) embrace the block time concept.

Of course, in this model, material physical objects are 4-dimensional, embedded in a 4-dimensional universe. And material bodies therefore do not move at all--being frozen into place as 4-dimensional objects strung out along their world lines (extending into the 4th dimension). So, it's left up to consciousness to do the moving. One picture has consciousness moving along the world line at the speed of light--which accounts for the same speed of light for all observers.

5. Apr 19, 2012

### pulsartoaster

In a nutshell, your mass possess a correlation with your momentum, to the point you become ridiculously massive once you approach the speed of light. As you most likely know, an object's mass is directly porportional to the effect of time on it. Thus, the following rules are valid according to the laws of physics and general relativity:

1. Time stops utterly at light speed.
2. Time begins to move in the opposite direction once you exceed the speed of light.

6. Apr 19, 2012

### phinds

Yes, but that's a mathematical fiction that as far as is known has no basis in reality.