Why the Galileo transformations are not correct for inertial systems

1. Sep 23, 2008

Physicsissuef

Why the Galileo transformations are not correct for inertial systems which are traveling close to the speed of light? What made Lorentz to correct this?

2. Sep 23, 2008

bernhard.rothenstein

Re: transformations

because they are not able to account for relativistic effects like time dilation and length contraction. Lorentz extended them imposing the condition that they should account for them.

3. Sep 23, 2008

JustinLevy

Re: transformations

No, and that is not how Einstein derived them either. Those can be derived from relativity, but they weren't conditions that were imposed to arrive at lorentz transformations. (I do not believe there even was any experimental evidence of time dilation for Lorentz or Einstein to use at the time.)

The correction came from looking at electromagnetism. Luckily this was already written in its correct form before special relativity was "discovered". Unlike all the other empirical laws of the time, electromagnetism did not look the same in another frame if you applied a Galilean transformation. This confused many people.

Lorentz created a coordinate transformation specifically to make the equations of electromagnetism "look" the same as in the original inertial frame. I say "look" because he believed this was just a nice mathematical trick and had no real physical significance.

Later Einstein postulated that ALL physical laws should look the same in inertial frames ... it turns out this was correct, for with better measurements it turned out Newton's laws needed to be adjusted to have the same Lorentz symmetry as electromagnetism ... and even the unknown forces at the time (weak and strong nuclear force) turned out to have this symmetry as well.

4. Sep 23, 2008

bernhard.rothenstein

Re: transformations

5. Sep 24, 2008

Physicsissuef

Re: transformations

Thanks for the posts. First, I was confused, since the length should not depend from the speed. So I also think like Bernhard Rothenstein that there are some length contractions and time dilation.

6. Sep 24, 2008

Mentz114

Re: transformations

I agree with Justin Levy. Einstein realised that Gallilean transformations did not work with electromagnetisn as described by Maxwell's equations. Most people were surprised by the subsequent predictions of length contraction and time dilation.

7. Sep 25, 2008

Physicsissuef

Re: transformations

I think Michelson realized that Galilean transformations did not work with electromagnetism, using the Michelson interferometer.

8. Sep 25, 2008

bernhard.rothenstein

Re: transformations

I think that the problem is not about what Einstein did. Stating his postulates and starting to teach special relativity it is not compulsory to mention Maxwell's equations. There are many ways to do that. The problem is if teaching special relativity it is compulsory to respect history, without diminishing Einstein's contribution! I think that doing so we gain more audience. Of course I respect the oppinions of others.