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Old 20-08-2009, 07:21 PM
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sjastro
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Quote:
Originally Posted by Morepower View Post
This has probably already been answered, but, if the beams are travelling toward each other at almost the speed of light at what relative speed do they collide at ? Nearly double the speed of light ? Or is there some "speed of light" rule preventing such collision velocities ?
If the 2 beams approach each other at say 0.99c, Galilean relativity or addition velocity doesn't apply as the approach velocity is 0.99c+0.99c=1.98c which obviously exceeds the speed of light.

Using special relativity the approach velocity is (0.99c+0.99c)/(1+(0.99c*0.99c)/c^2)= 0.9999c.

The reason this occurs is that in the LHC frame of reference, the time it takes for 2 opposing particle beams to collide with each other will take longer when compared to the particles frame of reference. This is time dilation which preserves the constancy of the speed of light in all frames of references and prevents observers measuring speeds greater than the speed of light.

Regards

Steven

Last edited by sjastro; 20-08-2009 at 07:38 PM.
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