Frequently Asked Questions

The following are questions submitted to us. Helen Quinn, content provider for this web site, offers answers to the questions.

1. Why is so much energy produced when an atom is split or fused?
2. More about time dilation
3. How does a cyclotron work?
4. Have quarks been observed and isolated in the laboratory?
5. Is mass always conserved?
6. How can the exchange of a photon attract a proton and an electron, yet repel two electrons?
7. More about the speed of light.
8. I was looking for a SU3 chart of the quark model.
9. Why is the visual spectrum continuous if it is produced by electrons going from one quantum state to another within the atom?
10. Time, microphysical processes, and probability.

FAQ7: More about the speed of light.

Question:

I am still puzzled as to why every object's velocity is relative to the observer's frame of reference except light, which will always have a constant speed regardless of the frame of reference.

Response:

The speed of light is the same for all observers.

Its an idea that's given many people sleepless nights -- its one of those things that you cannot "understand" in the usual way.

Let me try to make this point clear. Einstein's insight was that if and only if he made this postulate (note postulate means, to start with he assumed it for the sake of argument) then he could develop a theory that gave consistent answers for all processes involving light and fast moving particles. That theory is special relativity. It has now been tested in so many ways that we must accept that the observations are telling us that Einstein's postulate is correct.

Actually Einstein had some clues before he made this postulate, it is hidden in the mathematics of Maxwell's equations, where the quantity c appears as a constant independent of frame of reference. He didn't just make a wild guess that somehow turned out right, rather he took seriously the predictions of an already well-developed theory of electromagnetism as they applied to electromagnetic radiation, namely light waves, radio waves etc. (See the article about physicists and equations in today's NY time Science Times for comments about taking the equations seriously --this is another example.)

So we don't understand it from our everyday experience, but we know it is true based on experiments since Einstein pointed it out to us.