Recent content by dyb

Thanks!

To understand the theorem, I'd need to understand what a differentiable symmetry is, what Lagrangian is, and so forth. If I knew all that, I wouldn't be asking. Can it be pinpointed down to something more simple? Can you give a simplified answer?

Let's assume I simulate a number of particles using a computer program. I teach the particles to move according to F=ma. The F acting on each particle will be the sum of all forces to other particles according to F=m1*m2/distance^2. I give the particles a set of initial positions and...

Thanks everyone I now have a better understanding of relativity on the event horizon!

I understand that depending on the coordinate the interpretation might be different, although in a sense they give the same ultimate conclusion. What happens if the black hole evaporated shortly after the object fell into the black hole (from the falling object's time)? Is that an event that...

Is it really just an optical illusion? Because if the person falling into the black hole decided to return to the distant observer before reaching the event horizon, and they would compare clocks, it would turn out that his clock actually did run slower.

I see, thanks! So is that right: If the object falling into the black hole encoded some information on a light beam and sent it to the outside observer, that light beam would get red-shifted while traveling outward. Whatever information were modulated onto that beam, it would reach the...

When I look at a minkowski diagram for a black hole I can see that time goes to infinity for the outside observer while the infalling object approaches the black hole. That means that for an outside observer, it takes an infinite amount of time until the infalling object reaches the event...

Perhaps an analogy you will understand: Consider the number 10/9. It is 1.1111111... with an infinite number of 1's after the decimal point. Now you may argue that 1/9 is the 10th of 10/9, so the decimal digits get shifted by one to the right and therefore there must be one additional 1 after...

If the universe were infinite and existed for an infinite amount of time and the universe weren't expanding, and the universe had the same kind of distribution of galaxies everywhere, then night would be bright as day because no matter what direction you look there would be light coming from...

Thanks for all the replies. Yes, I meant local hidden variable. The story is derived more or less from the proof of Bell's theorem.

Everyday analogy why hidden variables can’t explain entanglement I tried to come up with an everyday “obvious” analogy that explains why a hidden variable theory cannot explain quantum entanglement. Here’s the story: There are two guests and one moderator on a stage. The moderator...

Excellent answer! Thanks a lot. One of the most intuitive examples on the net. I'm actually getting a feeling for it now and have examples I can relate to.

Does that mean that contravariant vs. covariant is not inverse behavior but something like inverse + transposed in linear algebra? Because if rotation doesn't matter it can't be inverse.

I have a question about covariant and contravariant vectors. I tried making concrete examples and in one example I succeed, in another I fail. It is said that displacement vectors transform contravariantly, and gradients of a scalar transform covariantly. I can get the whole story working in...