Gravitational force between 2 bodies at relativistic speeds

[Guest blaze]

Hi all,

 

Newton's law of gravitation states the force between 2 masses M1 and M2 is equal to F = G M1 M2/ d^2

 

My question is simple:

 

Case 1:

 

If both masses are both travelling at relativistic speeds (referred to observer), next to each other, on parallel paths, what would the force be.

 

Case 2:

 

If both masses are travelling at relativistic speeds (referred to observer), on the same path, one behind the other, what would the force be.

 

Thanks

Blaze.

[Radical Edward]

if they are travelling at relativistic speeds, but stationary with respect to one another (as in case 2, and mostl likely case 1) then there is no difference on the force between them as observed from their own inertial frame. However there will be a difference between the force you observe on them, and the force they observe, and yu can find this by replacing d with the lorentz contraction.

[Guest blaze]

Let me see if I got it right (assume both masses are equal):

 

From the moving mass reference frame, the force between the masses will not change.

 

From the stationary reference frame,

 

F= y^2 (GMM/d^2) ..... y=Lorentz factor

 

or alternatively we can say that in such a case:

 

F= G (yM)(yM)/d^2

 

So if the stationary observer wants to hold the masses at a fixed distance from each other, he would exert the same force as he normally needs with 2 masses having mass ym each.

 

Right?

[TrueHeart]

Case1=case2=no difference whatsoever in the gravitational force between observed speeding masses. Think about it: either they attract more or they don't -- and that's an absolute; and relativity isn't about absolutes!