# Time dilation

1. Nov 9, 2006

### Tonyt88

Relativity

Two balls move with speed v along a line toward two people standing along the same line. The proper distance b/w the people is L, and the proper distance b/w the ball is γL [Note: γ is gamma]. Due to length contraction, the people measure the distance b/w the ball to be L, so the balls pass the people simultaneously (as measured by the people). Assume tha the people's watches both read T at this time. If the people catch the balls, then the resulting proper distance b/w the balls becomes L, which is shorter than the inital proper length of γL [Note: γ is gamma].

By working in the frame in which the balls are initially at rest, explain how the distance b/w the balls decreases from γL to L.

Last edited: Nov 9, 2006
2. Nov 9, 2006

### OlderDan

Hint: Spatially separated events that are simultaneous in one reference frame may not be simultatneous in a reference frame in motion relative to the first frame.