Special Relativity Thought Experiments

[surreptitious57]

If special relativity is literally true one would be able to traverse the entire universe within a lifetime by travelling at less than the

speed of light and return to find this galaxy long dead. If one could travel at the speed of light then the universe would not even

exist. And if one could travel faster than the speed of light one would have returned to this galaxy before having actually set off

[ajb]

Time dilation effects are measured, so in that particular sense, special relativity is 'literally true'. If one could break the laws of physics then it is impossible to say what would exist or not. Also we know any object that travels with a speed faster than light then it is possible to find an inertial reference frame for which that object is moving backwards in time.

 

What you have said seems to be okay, if a bit pop-sci in nature. So what is it you actually want to discuss?

[Sensei]

Acceleration from v=0 to v=0.999c would be taking a long time by itself.

 

For exercise calculate how long approximately it would take with a=g=9.81 m/s^2

and how long it would take with 5g, 10g for example.

 

Acceleration with constant a=10g would be pretty unpleasant for astronauts.

Not to mention they would not be able to move and do anything.

 

Significantly exceeding these values would kill living organism on board.

The most of people lose consciousness between 5g-10g.

 

Special Relativity is widely used while calculating decay of unstable particles, unstable isotopes, and high energy physics to calculate particles created during their collisions, and matter, antimatter creation and annihilation.

Edited February 10, 2016 by Sensei

[Strange]

If special relativity is literally true one would be able to traverse the entire universe within a lifetime by travelling at less than the

speed of light and return to find this galaxy long dead.

 

This is true. (Although, "the entire universe" probably renders it impossible. The observable universe, perhaps.)

 

If one could travel at the speed of light then the universe would not even

exist. And if one could travel faster than the speed of light one would have returned to this galaxy before having actually set off

 

This is impossible. But photons travel at the speed of light and the universe still seems to exist, so I'm not sure your conclusion is justified.

[Daecon]

Surely if one could travel at the speed of light, then the Universe would appear frozen at the instant you reached that speed.

 

As for travelling faster than light, did Concord manage to travel backwards in, uh... sound?

[ajb]

Surely if one could travel at the speed of light, then the Universe would appear frozen at the instant you reached that speed.

We do not really have any idea what the Universe would look like. The problem is that at the speed of light there are no inertial frames of reference for which that object is at rest. We do not have a 'point of view' as we mean it in special relativity for objects traveling at the speed of light, for example photons.