What are the energy implications of time travel into the future?

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The discussion centers on the theoretical energy implications of a train traveling at near-light speed to achieve time dilation, where one week on the train equates to 100 years on Earth. Key points include the challenge of powering the train, as energy requirements differ based on the frame of reference, leading to confusion about energy conservation and usage. Length contraction is highlighted as a critical factor, allowing the train to complete its journey in a week while appearing to traverse a much longer distance from an Earth perspective. The conversation emphasizes that energy is frame-variant, meaning its value can change depending on the observer's perspective, but the total energy remains conserved. Ultimately, the complexities of relativity and energy dynamics in different frames are underscored as essential to understanding this hypothetical scenario.
  • #31
What happens if inside the train we build another track that goes in circles, and we repeat this process over and over, would that mean that theoretically we can we can travel all the age of the unvierse in less than a second or a infinitesimal amount of time?
 
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  • #32
Rene Manzano said:
What happens if inside the train we build another track that goes in circles, and we repeat this process over and over, would that mean that theoretically we can we can travel all the age of the unvierse in less than a second or a infinitesimal amount of time?
That would be adding an implausibility on top of an implausibility.

The way to avoid all this implausibility is to just get in a spaceship and leave poor Earth in peace. Your ship has a engine that can run indefinitely. In theory, you could continue to accelerate until the universe flashes by at a billion years a second or faster. There's really no upper limit.
 
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  • #33
DaveC426913 said:
That would be adding an implausibility on top of an implausibility.

The way to avoid all this implausibility is to just get in a spaceship and leave poor Earth in peace. Your ship has a engine that can run indefinitely. In theory, you could continue to accelerate until the universe flashes by at a billion years a second or faster. There's really no upper limit.
Why wouldn't it work though?
 
  • #34
In principle, it would work. But it is implausible that we can build a train to go around the Earth at 99.99+% of the speed of light. Building a nested sequence of such trains is more implausible still. Why make a thought experiment complicated when one can simply imagine the original train going faster and achieving an identical effect?
 
  • #35
jbriggs444 said:
In principle, it would work. But it is implausible that we can build a train to go around the Earth at 99.99+% of the speed of light. Building a nested sequence of such trains is more implausible still. Why make a thought experiment complicated when one can simply imagine the original train going faster and achieving an identical effect?
It would actually complicate the part of my question about powering the train from outside. Won't it? What if i considered a different planet with a huge radius(compared to earth) so will it be possible then?
 
  • #36
Suraj M said:
What if i considered a different planet with a huge radius(compared to earth) so will it be possible then?
OK, so a planet one or two orders of magnitude larger than Earth.
So, instead of a billion g's, you've reduced it to 10 million g's.

Your occupants, rather than being a puddle of jam 1 micrometer thick, are a puddle of jam 100 micrometers thick. :wink:
 
  • #37
Now don't shift this thread to the fiction forum! :olduhh:
 
  • #38
Suraj M said:
Now don't shift this thread to the fiction forum! :olduhh:
It's been in danger of that since sentence 3 of post 1. :biggrin:
 

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