Recent content by user299792458

Isn't a spherically symmetric transverse wave inconsistent with the "hairy ball" theorem that has been mentioned here?

I've never heard of that theorem (just looked it up in Wikipedia), but that's basically what I was thinking, that you can't have a truly spherically symmetric EM wave. It seems that even the magnitude of the electric field vectors can't be completely spherically symmetric? So I guess it varies...

What does the electric field of a "spherical wave" look like? You often hear about spherical light waves. For example, something like a light bulb is said to emit waves which are more or less spherical. Let's assume this light bulb is perfectrly round and emits in all directions (as opposed to...

It is often stated that ANY accelerating charge radiates, so this includes uniformly accelerating charges. But the radiation reaction force is proportional to the THIRD derivative of x, so it vanishes when acceleration is constant. What's the deal here? Here's a graph which supposedly shows...

:biggrin: I'm just saying, I'm not very impressed with this cheap trick. There are many impressive tricks various animals can do, but I don't think this is one of them.

Twiggy the Water Skiing Squirrel - OH REALLY? Ok, you've probably seen this, the squirrel which, supposedly, water skis. But to me, it looks like the damn thing is simply riding in a boat (made to look like a pair of water skis) which is being pulled by another boat. I find it annoying that...

Um, and how many parking lots have STAIRS? Parking spots for the "disabled" are merely closer to the entrance than the other ones, but it's not like if you park somewhere else you have to go down an extra flight of stairs. And I think if you add spikes to that thing it would be better for...

I don't disagree with you about the possibility that prosthetics do provide an advantage for maintaining speed (although certainly not for accelerating, to accelerate quickly with prosthetics, they would need a built in power source). However, you do have to consider that all other double...

I'm sure (or hope, anyway) people know that the ankle is operated by the calf muscle. Here are some links, you can find more by googling "Oscar Pistorius": http://sport.independent.co.uk/olympics/article2377707.ece http://www.wired.com/wired/archive/15.03/blade.html...

Biological legs vs Cheetah prosthetic legs - which is better for running? EDIT: I misspelled "which" in the subject line, how embarrassing. You may have heard of Oscar Pistorius, a double below-knee amputee from South Africa who recently won the silver medal in the 400m at the South African...

I don't get it, why make a fool of yourself? What does electrical engineering have to do with relativity anyway?!

jeez, the camera work is annoying...

Well, at point x the positive charge on the right creates a field kq/(x-a)^2, this field is directed in the right direction. The negative charge creates a field of magnitude kq/(x+a)^2, and this field is pointed to the left. To get the net field, subtract the field created by negative charge...

I just don't think what he's doing is very smart. I won't be surprised if he ends up much worse off than the girl in my previous post. I've already seen some clip of a guy putting his arm in a croc's mouth, it didn't go too well for him...