# Speed of light and planck length

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1. Oct 22, 2014

### brianhurren

I was thinking about the special theory of relativity and how as one approaches the speed of light, ones length contracts. what I would like to know is: If I had an object and I accelerated it towards the speed of light and it contracts in the direction of travel, what happens when it reaches planck length?

2. Oct 22, 2014

### tzimie

Check: http://en.wikipedia.org/wiki/Doubly_special_relativity

3. Oct 22, 2014

### ghwellsjr

Nothing, at least not according to Special Relativity. You're confusing Length Contraction, which is a coordinate effect defined by SR, with what happens to an object when you accelerate it, for which SR has nothing to say.

You can take any object and define it as stationary according to an Inertial Reference Frame (IRF). Then you can transform the dimensions of the object according to another IRF moving at any speed such that it is now shorter than the Planck length. This is purely a mathematical exercise, does not require any acceleration, and does not affect the object at all.

If you actually took an object and accelerated it to the same speed, it would depend on how you accelerated it as to what actually happened to the object. This would require extensive knowledge and specification on your part about the nature of the material in the object, how you propose to accelerate it, how you propose to remove the acceleration, and things like that.

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