Recent content by twoslit

This may seem like a silly question, but does Bell's theorem and the experimental design giving rise to the EPR phenomenon apply only to photons? Or could one, in principle, demonstrate this with entanglement of things with a rest mass, so moving at less than the speed of light? (I realize of...

Recoil has a direction, so it is a vector quantity. Momentum is a vector. Energy is not a vector. To equate recoil with energy cannot be correct.

When you pushed it, you gave it a finite amount of kinetic energy. It still has that energy later (assuming nothing else happens to it), and it will have it as long as it keeps moving. This energy lasts as long as the body is moving, but it does not increase. It is the same amount of energy as...

You got the paradox right, although you should use language more carefully. "Part of" has no meaning in set theory. What you should say is, A will be an element of N just when A is not an element of itself. What does this tell us about sets? That is an enormous question, with about a century...

Several points need to be made here. First, logical notions like validity, tautology, contradiction etc. are all defined purely in terms of truth, not usefulness or non-circularity or redundancy. So while it might be somewhat useless to derive one tautology from another, this is not logically...

The point that may be giving you trouble is that the integral is taken along the path, while the variation expressed by the delta is varying the path itself. Think of a path from A to B wiggling slightly: the wiggle is the delta.

BTW, to get a good intuitive feel for what a real hovercraft behaves like, watch or other movies of the hovercraft car ferry service across the English Channel. As you will see, it steers using directed airfoils at the corners, having no wheels or direct contact with the surface, and you can...

You might try having your craft have emergency booster JATO units which give it a brief (and spectacular) boost upwards from where it can glide back to the landing. That gets rid of the need for any special physics, of course.

The phrasing "just a theory" sounds worryingly reminiscent of creationist attacks on evolution. If your DoE friends feel that Newtonian gravitation is somehow superior to, or more certain than, relativity, they are mistaken.