# Lorentz-Fitzgerald Contraction or Time Dilation?

1. May 14, 2007

### Tlatoani

If I can explain a special relativistic effect with both Lorentz-Fitzgerald Contraction and Time Dilation, then which one is the correct answer?

Because, for example in the experiment with the muons coming from the atmosphere, the explanation was Time Dilation, but we can explain it with length contraction too, so which one is the correct answer?

2. May 14, 2007

### phyti

If your are talking about the extended lifetime of the muon, then it is the result of time dilation.

3. May 14, 2007

### Tlatoani

And can you tell me why is it time dilation instead of length contraction?

Both explain the same effect just fine. How do you know when it is length contraction or when it is time dilation?

4. May 14, 2007

### JesseM

In different frames there are different explanations--in the Earth's frame you must use time dilation to explain how a muon created by a cosmic ray hitting the upper atmosphere can make it all the way to the surface before decaying, while in the muon's frame you must use length contraction. There is no preferred frame, so neither explanation is "more correct" than the other.

5. Feb 16, 2009

### Ken More

Does the question "If I can explain a special relativistic effect with both Lorentz-Fitzgerald Contraction and Time Dilation, then which one is the correct answer?" suggests that one would be correct and the other would not be correct? Why can't both be correct? Then it woud not matter which explaination was used unless you know something that I do not know. See "Proof of Special Relativity Length Contraction Assumption" for an explaination that equates Lorentz-Fitzgerald Contraction with Time Dialation via the clock synchronization factor.

6. Feb 16, 2009

Staff Emeritus
This thread is two years old, but I agree: it's not an either-or thing.

7. Feb 16, 2009

### bernhard.rothenstein

If it is about the derivation of a formula which accounts for a special relativistic effect you find in the literature of the subject papers in which it is derived from formulas which account for another relativistic effect. So the addtion law of parallel velocities could be derived invoking length contraction and time dilation, the formula which accounts for the Doppler shift could be derived invoking the formula which accounts for time dilation, the formulas which account for the Lorentz transformtion could be derived from Lorentz contraction...
If you are interested in I could give you a list of such approaches.
I think that Asher Peres' paper "Relativistic telemetry' Am.J.Phys. is a good example for the problem we discuss.

8. Feb 17, 2009

### Naty1

I thought they were.

JesseM provided what I thought was the correct and clear explanation: