Speed of light and planck length

[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?

 

[tzimie]

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

The motivation to these proposals is mainly theoretical, based on the following observation: The Planck energy is expected to play a fundamental role in a theory of quantum gravity, setting the scale at which quantum gravity effects cannot be neglected and new phenomena might become important. If special relativity is to hold up exactly to this scale, different observers would observe quantum gravity effects at different scales, due to the Lorentz–FitzGerald contraction, in contradiction to the principle that all inertial observers should be able to describe phenomena by the same physical laws.

 

[ghwellsjr]

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?

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.