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Q & A: postulates of special relativity

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Most recent answer: 02/23/2011
Q:
state and explain the 2 postulates of special relativity
- jose (age 18)
mexia, tx, limestone
A:
That sounds a bit more like a command or homework problem than a question, but here goes:

1. The laws of physics look exactly the same to you as they do to someone moving at a fixed velocity with respect you.

2. The laws of physics include Maxwell's equations for electromagnetism.

Why is that strange? Maxwell's equations imply that electromagnetic waves in empty space travel at the speed of light (an example of an electromagnetic wave) in all directions. You would think intuitively that if you ran after a wave fast enough, it would not be traveling so fast relative to you. But then Maxwell's equations would seem false from your point of view. So either Einstein or your intuition is wrong. Measurement shows that Einstein was right.


The reason Einstein can be right is that lengths and times also change as you switch between different points of view. We don't have good intuition for that, because those effects are very small when the velocity differences are much less than the speed of light. So we intuitively treat them as zero.

Mike W.



(published on 02/23/2011)

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