- #1
MrBlank
- 17
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Alice and Bob are initially in the same inertial frame. There are 2 point test masses m1 and m2. Initially m1 is at the origin and m2 is on the positive x-axis. At time zero, m1 is instantaneously accelerated to velocity Vx in the positive x-direction. After some time, m1 collides with m2.
An instant before time zero, Bob is instantaneously accelerated to velocity Vy in the negative y-direction, from Alice’s point of view. From Bob’s point of view, m1 and m2 will have velocity Vy in the positive y-direction before m1 is accelerated. After m1 is accelerated in the positive x-direction, it will have a velocity less than Vy in the positive y-direction. See
https://www.physicsforums.com/threads/acceleration-in-special-relativity-in-2-dimensions.977658/
It will appear to Bob that m1 and m2 do not collide. However, in reality they do collide. Bob will see that m1 and m2 are affected by this collision, even though he observed no collision.
It’s possible to adjust the initial position of m2 so that Alice observes that m1 and m2 do not collide, but Bob observes that they do collide. However, in reality they do not collide. Bob will observe m1 and m2 pass through each other with no effect on either mass.
As far as I can tell, in order to know if a mass is involved in any collisions, you must be in the rest frame of the mass.
Is this correct?
An instant before time zero, Bob is instantaneously accelerated to velocity Vy in the negative y-direction, from Alice’s point of view. From Bob’s point of view, m1 and m2 will have velocity Vy in the positive y-direction before m1 is accelerated. After m1 is accelerated in the positive x-direction, it will have a velocity less than Vy in the positive y-direction. See
https://www.physicsforums.com/threads/acceleration-in-special-relativity-in-2-dimensions.977658/
It will appear to Bob that m1 and m2 do not collide. However, in reality they do collide. Bob will see that m1 and m2 are affected by this collision, even though he observed no collision.
It’s possible to adjust the initial position of m2 so that Alice observes that m1 and m2 do not collide, but Bob observes that they do collide. However, in reality they do not collide. Bob will observe m1 and m2 pass through each other with no effect on either mass.
As far as I can tell, in order to know if a mass is involved in any collisions, you must be in the rest frame of the mass.
Is this correct?