why we use lorentz transformation istead of galelian transformation

Question

anonymous · Answer

The galilean transformation assumes that time is an absolute, it does not transforms time from one system to the order. In fact, this is not correct when the relative velocity involved is close to the speed of light. In this case, Lorentz gives the correct transformation. So actually the right transformation to use will depend on your problem.

anonymous · Answer

thnx

anonymous · Answer

As Marianne has stated above, the Galilean transformation is used if one assumes that space and time are absolute.  Einstein showed that because the speed of light was constant in each inertial frame (meaning regardless of of an observers velocity, the observer will always measure the velocity of light to be the same).  This means that time and space become relative concepts, and so the Lorentz transformation is the correct transformation to use.

However, if the velocity of objects is much less than that of the speed of light, then the Lorentz transformation is approximated by the Galilean transformation.  If one always uses the Lorentz transformation, then you will always get the correct answer.  Galilean transformation will only give the approximately correct answer at small velocities relative to that of light, and will increasingly get worse as the relative velocity increases.  

As an example, consider two objects heading towards each other at 0.6c (measured from an rest frame external to both objects) where c is teh speed of light. If one were to apply a Galilean transformation, we would end up with one object measuring the speed of approach of the other as 1.2c from its rest frame (which is wrong as objects cannot exceed the speed of light).  However, applying a Lorentz transform, the object would measure the speed of approach of the other (again from the objects rest frame) as being 0.88c, which is less than the speed of light.  Therefore, at relativistic speeds, the Galilean transformation can not only give wrong answers, but answers that are not permitted by the principle of relativity.