Undergrad How do forces change with speed?

[Hyperspaced]

TL;DR

What happens to magnetism and gravitation when materia hits near lightspeed?

Hey dear physics community :)

I ask myself what exactly happens to forces between materia when the materia hits near lightspeed.

I know, that for an objective bystander watching let's say elon in his rocket with 99,99999% the speed of light, that the time goes slower, the mass of the rocket goes up and the length of the rocket decreases.

What i ask myself now is what happens to all the forces like gravitation and magnetism. Gravitation and magnetism don't change for elon on the spaceship, so the other way around it means they have to decrease for the objective bystander aren't they?

Thanks a lot for your time and knowledge :)

 

[anorlunda]

Answer it yourself. Right now, you are going 99,99999% the speed of light relative to something else. In the reference frame of the other something, you are the one traveling fast.

How does it feel?

p.s. All linear speeds are relative. No speed is absolute.

 

[Ibix]

objective bystander

No such thing. But for any observer who sees the rocket move, some of the things you wrote are true.

the time goes slower

The rockets tick slower as measured by clocks that see it as moving, yes.

the mass of the rocket goes up

No - "mass" means the invariant mass which does not change. Relativistic mass does increase with speed, but is a long deprecated concept that causes more confusion than it's worth.

the length of the rocket decreases.

Again, as measured by anyone who sees the rocket moving, yes.

What i ask myself now is what happens to all the forces like gravitation and magnetism.

What do you mean? A key point of relativity is that all laws of physics are the same in all frames of reference, so all forces work the same way at all speeds. Electric and magnetic fields do transform - a field that is a pure electric or pure magnetic field will be seen by observers in other frames as electromagnetic fields.

Gravitational fields are more complicated. They are not forces, but are rather spacetime curvature. Again, the laws are the same at all speeds, but the fields transform. There are loose analogies with electromagnetic fields in the way the transformed fields behave, but really you need to do the maths for that - I'm not sure there's a non-technical description of it.

 

[jartsa]

I ask myself what exactly happens to forces between materia when the materia hits near lightspeed.

http://www.sciencebits.com/Transformation-Forces-Relativity