Inverse Lorentz Transforms

Could you please explain me that why can't we use inverse Lorentz transformation to prove length contraction in the case of two frames that are in relative motion with each other. I could derive the relation by using Lorentz transformation but not through inverse Lorentz transformation. Its exactly opposite in the case of time dilation. There we are supposed to use inverse Lorentz transformation and not Lorentz transformation. Why is it so?
- Gamini (age 18)
Jaipur, Rajasthan, India

I'm puzzled by the question. You can use a Lorentz transform to derive any of the coordinate changes between frames in Special Relativity, including both the effects you mentioned. The inverse of the transform with relative velocity v is just the transform with -v substituted for v. Perhaps if you explained the question further we could see what the issue is.

Mike W.

(published on 07/31/2012)