All About Light
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|On the previous page, I discussed the Doppler effect, which stated, that the emitted and received frequencies of EM waves are not the same if the source and the observer move relative to each of other.
On this page, I will begin discussion of topics related to Lorentz contraction. First, I will show a consequence of Einstein's relativity what might interest lawyers.
Here is the deal: The law says that movie theaters spread around the US cannot show the premier of the new Star Wars movie until May 17. Every movie theater knows that it will be a great hit. To make the most money out of it, they would like to show Star Wars as early as possible. However, they are constrained by the May 17 date. They all decided to show the premier at the earliest possible time, at 0:00 ( midnight) on May 17. They synchronized their watches so that no one would get in trouble with the law.
However, there is a picky lawyer, who used to be a physicist, he took a class in special relativity, and learned a very important consequence of relativity, which is:
Two simultaneous events in one frame of reference are no longer simultaneous for observers in a moving frame of reference.
That is, if our lawyer sits on an airplane traveling at a very high speed, from west to east (suppose he is above Illinois when his watch shows midnight), he will observe that the Illinois theater is showing the movie at the right time, 0:00.
But according to his watch, every theater east of him is showing the movie after midnight. He thinks the managers are not very smart: they could have started the film earlier.
On the other hand, every theater west of him, started showing the movie BEFORE midnight!!! Those theaters he will sue. And he will make o lot of money if the U.S. law system fails to incorporate relativistic effects.
Conclusion: Watches synchronized in one frame of reference, are not synchronized in other, moving frames of reference. This has a very big impact on how the lengths of objects appear for different observers. Please find the discussion of the Lorentz contraction on the next page.
|last modified 1/5/2001 email Fermilab|