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Physics/The principle of relativity


The Earth orbits the Sun. But the Sun also orbits the Earth. A ship moves relative to the shore, but the shore also moves relative to the ship. The smoke rises from a candle in a cabin just the same whether the cabin is on the shore or on the ship. In a universe that contains only two objects, you should not be able to tell me that one of them is definitely moving. It should not matter that they are two different sizes. It should not matter if one of them is the size of a planet or the size of a bicycle. So why does it seem to matter if the other one is a photon? Einstein tells me that it is definitely the photon that is moving and he even tries to tell me how fast. So which is correct: the principle of relativity or the constant speed of light?

No, they would orbit around their center of mass.  And the photon still has definite energy and still satisfies the wave equation which determines its speed relative to a massive object.  They're not inconsistent, if you know enough physics, not inconsistent at all.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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