# Point masses reaching c

1. May 6, 2007

### mr200backstrok

i was sitting here wondering about something, and i'm not sure, so ill ask.

suppose you take 2 point masses, say 1 kg each, 1 meter apart, and release them. Would they ever reach the speed of light? As they got very close, the $$F _{g}$$ would near infinity ( $$\lim _{distance \rightarrow 0} F_{g} = \infty$$ ), which means that it would accelerate at an infinite rate past the speed of light. but, relativity doesnt allow that, and would start reducing the acceleration as the velocity approached c. so, is $$\lim _{distance \rightarrow 0} v = c$$ (if v is velocity and c is the speed of light)?

Last edited: May 6, 2007
2. May 6, 2007

### Office_Shredder

Staff Emeritus
as particles increase in speed, they also increase in mass (and the mass can go to infinity). So the energy would, in fact, be infinite, but not the velocity

3. May 6, 2007

### mathman

Another issue that has to be considered is that as the two particles get close to each other, the point assumption breaks down. Also quantum effects would begin to play a role.

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