Recent content by Jeremy87

Well I kind of figured out that the photon's energy does in fact depend on the gravitational field. What about kinetic energy? If you store energy by making a sphere spin at high speed, what will happen to this spin if you move it into a different gravitational potential?

What? Moving mass against gravity. The recombination of the matter&antimatter that you created down in the gravity well. Or any other energy<->matter conversion example you like.

Meh, made the thread when I was tired, hoping for an answer in the morning =). Now the thread title is kind of misleading, and the example wasn't a very good one... I was of course talking about gravitational potential energy. Say you create matter and anti-matter using E=mc^2 at sea level...

Where does the potential energy go if you carry uranium to a nuclear power plant on the top of a mountain and part of its mass becomes energy?

Make a sudden movement at the end of a long rope, and you will see a wave propagate even though no part of the rope follows the wave. The rope won't oscillate because it loses its energy hitting the ground, but water will keep moving until friction stops it. So the waves aren't water moving...

Well, I am a physics student, just not of this particular field. I like to understand how things work. Even if their effects are purely academic and likely non-measurable (like the drag and orbits scenarios), saying they don't exist would just confuse me more. I hate it when people ignore things...

Thanks for all the answers. Just to make a few things clear: - In smaller things, like a solid rock or even small enough galaxy clusters, the atoms (or galaxies) are actually moving *toward* each other relative the space "beneath them", if their distances stay constant? - The expansion is kind...

The thing I find most difficult to understand is how an infinitely large space can expand further. I mean, I can say it does, and I can probably do whatever math it requires, but it just doesn't click in my head. It's a lot easier to imagine a fixed (infinite) space, with a finite amount of...

So basically, mathematically it's correct that space is indeed expanding? Would it still be "OK" to think everything in it is shrinking instead as long as I'm aware that it's really not the case and I'm not a professional cosmologist? Because I find this easier to get an intuitive grasp of, and...

I'm trying to get some kind of intuitive understanding of the Big Bang and the expansion of space. Would it be equivalent to think that instead of space expanding, everything in it is getting smaller, including matter, the speed of light etc? In the beginning matter would be too large to exist...

I took a few pictures too before I saw it was already done. Anyway, the more the better I guess =). Found it works really well by looking between two credit cards or similar. For my picture I had a piece of paper pressed between the cards to force a very thin opening. It looked *much* better in...

I think this stretching is a result of the aperture getting smaller from only one direction. The blur from defocusing comes from light from the source going through different parts of the aperture and landing on different parts of the retina. Eliminate one side of these light beams and you...

I've noticed this too (I need glasses), but never had any real use for it. However, I think that's just limiting the amount of light coming in from larger angles from the object, which makes lense focus errors smaller. The easiest way for me to notice this diffraction pattern is to be in a dark...

Well arc lamps send current through the initially ionized path. A lightning step doesn't really connect to anywhere so there's no continuous current, but maybe just ionizing the air does momentarily light it up slightly. I've seen some slow-motion videos, and the incomplete branches do a bright...

I've been reading about how lightning occurs, but I have some questions that are never answered. 1. What exactly is the stepped leader? What in it gives off light before the connection is made and current starts flowing? Are there already some electrons flowing into this newly connected point...