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

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Discussion Overview

The discussion revolves around the energy implications of hypothetical time travel into the future using a high-speed train that circumnavigates the Earth. Participants explore the theoretical aspects of time dilation, energy requirements, and frame-dependent energy calculations, engaging with concepts from physics and relativity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes a concept where a train traveling at high speeds could allow passengers to experience time differently than those on Earth, raising questions about the energy required for such a journey.
  • Another participant argues that the kinetic energy involved in such a system would be immense, potentially making the Earth unstable, and questions the feasibility of powering the train.
  • Some participants note that energy is frame-dependent, suggesting that energy calculations differ based on the observer's frame of reference.
  • A participant introduces the idea of length contraction, explaining that the distance traveled by the train could be significantly shorter due to relativistic effects, which might affect energy requirements.
  • Several participants discuss the implications of kinetic energy calculations in different frames, using examples to illustrate how energy values can vary based on the observer's perspective.
  • There is a contention regarding whether the change in kinetic energy is absolute or relative, with differing opinions expressed on this point.

Areas of Agreement / Disagreement

Participants express multiple competing views on the energy implications of time travel and the nature of energy in different frames. The discussion remains unresolved, with no consensus on the feasibility or implications of the proposed time travel scenario.

Contextual Notes

Participants highlight limitations in understanding energy calculations, particularly regarding frame dependence and the assumptions underlying relativistic physics. Some mathematical steps and definitions remain unclear or unresolved.

  • #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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