How does time travel work based on Relativity?

[The Peon]

Please be gentle...

 

I am having difficulty in understanding how time travel works in regards to relativity. I read an explanation for relativity which explained that space time can be viewed as a grid, in which objects can be placed, and they would "bend" the grid to create a "slant" in the grid, causing the effects of gravity. Now using this same model for space/time, I fail to see how any one object in space, going at any speeds, could change time itself, since although the one object may be moving at a high rate of speed, or even warping the grid in a certain way, how this could effect the other objects on the grid? If I somehow could force myself back in "time," how could all matter in the universe travel with me to recreate the moment in time I was travelling to? Is not time constant? Am I missing something here (obviously)? I hope I am being clear on my confusion.. if thats possible. I have no true understanding of these matters and it would be fascinating to learn how time travel is possible... in "caveman" terms possibly using the "grid" analogy.

[mezarashi]

Actually I think you're a bit confused on the part that relativity doesn't suggest that time travel is possible. This means going to the future or into the past. The consequence of assuming that the speed of light is constant (a postulate for special relativity) is that time is relative (variant). The way you phrased it: "I fail to see how any one object in space, going at any speeds, could change time itself" is a bit misleading, because there is no universal time with relativity, as with there is no universal frame of reference.

 

The analogy with the grid is usually used to explain general relativity from a qualitative point of view. The time dilation effect (slowing down of time) suggested by special relativity is better shown using the light clock analogy. Special relativity says that two observers moving relative to each other will observe time slowing down in the others' frame of reference.

[The Peon]

Actually I think you're a bit confused on the part that relativity doesn't suggest that time travel is possible. This means going to the future or into the past. The consequence of assuming that the speed of light is constant (a postulate for special relativity) is that time is relative (variant). The way you phrased it: "I fail to see how any one object in space' date=' going at any speeds, could change time itself" is a bit misleading, because there is no universal time with relativity, as with there is no universal frame of reference.

 

The analogy with the grid is usually used to explain general relativity from a qualitative point of view. The time dilation effect (slowing down of time) suggested by special relativity is better shown using the light clock analogy. Special relativity says that two observers moving relative to each other will observe time slowing down in the others' frame of reference.[/quote']

 

Ahh I see, sorta.. But wouldnt what you described merely be an observational time travel, much like looking at distant galaxies? I still dont understand how sending something back in "time" would alter the entire fabric of the universe to mold to that one objects perspective and how it could effect the "future" in any way.

[danny8522003]

Are you talking along the lines of the grandfather paradox?

[The Peon]

Are you talking along the lines of the grandfather paradox?

 

I mean simply since time itself is just a measurement of energy in motion, to travel in "time" would require changing every particle in the entire universe. If I went back in "time" the existence that I was in would no longer be there since most matter cannot exist in two places at the same "time." I dont know if I am being clear, or perhaps I am not grasping this concept in the correct way.