## Main Question or Discussion Point

So we have covered relativity a couple weeks ago and I've been thinking about the twin paradox. It is when one twin travels on a high speed ship to some distant planet and back. But since all frames of reference are equivalent, each twin measures the other to be younger. My book explained that the paradox was solved because of the acceleration and turning around of the one ship and the fact that its speed is not entirely constant.

So my question is, since we are dealing with hypothetical near the speed of light velocity. What if we had a huge trampoline or something such that the ship could just bounce directly off and maintain its velocity without experiencing deceleration. Wouldn't this leave us with the original paradox?

I hope that makes sense...I am just not very satisfied with the resolution offered to me.

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Dale
Mentor
What if we had a huge trampoline or something such that the ship could just bounce directly off and maintain its velocity without experiencing deceleration.
Huh? A trampoline doesn't eliminate acceleration.

I'm just saying a hypothetical mechanism that can eliminate the acceleration and just shoot the ship back at the same velocity without the whole stopping, turning, etc. If there must be some transfer in energy, it would be insignificant and extremely brief.

I know there is no such mechanism, but we are working with hypothetics

DaveC426913
Gold Member
1] The net result of the thought experiment is that velocity A is turned into velocity B (probably -A but not necessary).

2] The definition of acceleration is a change in velocity.

Considering nothing else, you can see that it is futile to try to imagine how you could - even in principle - have 1] without 2].

DaveC426913
Gold Member
I'm just saying a hypothetical mechanism that can eliminate the acceleration and just shoot the ship back at the same velocity without the whole stopping, turning, etc. If there must be some transfer in energy, it would be insignificant and extremely brief.
Doing it quickly does not use less energy. It actually makes the rate of transfer arbitrarily large. Reduce the time of transfer from 1000 senconds to 1 second and you increase the rate of transfer by a thousand fold. (Since "rate" is simply total amount transferred divided by time)

Dale
Mentor
I know there is no such mechanism, but we are working with hypothetics
It has nothing to do with mechanisms, as DaveC mentions, it is just definitions. If the twin turns around then he accelerated by definition.

Got it! Thanks. That makes sense, I don't know what I was thinking. Relativity is just such an absurd concept!