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I'm not a physics student but have always been interested. That said my knowledge is very slim. I've always wondered why traveling faster than light would lead to time travel, I've poured over websites and other forums but they tend to descend into physics that is beyond me. Here is an outline of my current understanding,
Travelling faster than light would cause events to occur in a non-causal manner to some observers. This can lead to paradoxes.
What I don't understand is why observing something happening out of sequence is a problem and secondly how that can lead to time travel/paradoxes?
I'm best at understanding these things as real world examples so here's one I've thought up;
Alice, Bob, Claire and Dan are all located exactly 1 light minute away from each other in a straight line. I'm chatting to Bob telling him that I've invented an instantaneous teleporter. He dares me to try it so I activate it and instantly teleport to Claire. I understand that this would happen:
*Alice would see me hanging out with Bob, then she would see me disappear. Precisely 1 minute later she would see me appear by Claire.
*Bob would see me disappear, looking at Claire he would see me appear in 1 minute the same as Alice .
*Claire would see me with Bob before all of a sudden I appear in front of her. We can both watch for another minute at me and Bob before I disappear.
*Dan would see me with Bob when a second me would appear by Claire. Dan could see me and Claire looking at Bob until after a minute the me by Bob disappears.
The two things I struggle to understand is why this is a bad thing and how exactly it can be used to effect the past. In my mind if I teleport to Claire and teleport back to Bob before I see myself leave I won't bump into my past, ill arrive just after I left.
Any help would be most appreciated!
Travelling faster than light would cause events to occur in a non-causal manner to some observers. This can lead to paradoxes.
What I don't understand is why observing something happening out of sequence is a problem and secondly how that can lead to time travel/paradoxes?
I'm best at understanding these things as real world examples so here's one I've thought up;
Alice, Bob, Claire and Dan are all located exactly 1 light minute away from each other in a straight line. I'm chatting to Bob telling him that I've invented an instantaneous teleporter. He dares me to try it so I activate it and instantly teleport to Claire. I understand that this would happen:
*Alice would see me hanging out with Bob, then she would see me disappear. Precisely 1 minute later she would see me appear by Claire.
*Bob would see me disappear, looking at Claire he would see me appear in 1 minute the same as Alice .
*Claire would see me with Bob before all of a sudden I appear in front of her. We can both watch for another minute at me and Bob before I disappear.
*Dan would see me with Bob when a second me would appear by Claire. Dan could see me and Claire looking at Bob until after a minute the me by Bob disappears.
The two things I struggle to understand is why this is a bad thing and how exactly it can be used to effect the past. In my mind if I teleport to Claire and teleport back to Bob before I see myself leave I won't bump into my past, ill arrive just after I left.
Any help would be most appreciated!