Recent content by snoopies622

So to go back to the thoughts that led me to my original post - just to be certain : a single, isolated wire with an alternating current does not vibrate, correct? There's no self induced mechanical force happening? (even assuming it's coiled so there's a clear non-zero inductance)

The frequencies i heard were the ones just above the 440 A and the one an octave below that, which are two and three octaves above the 60 Hrz.

Interesting: using my musical keyboard and my ears, it sounds like to me the most prominent frequencies from my toaster are the ones 2 and 3 octaves above the wall 60 hertz alternating current. (Of course, that may be where my ears are more sensitive.)

Thanks, everyone! I've been asking this site questions for almost twenty years now - it's been priceless.

Thanks, Baluncore!

Unfortunately i lost my tuning fork long ago, so I'm only making an assumption about the relationship between these two frequencies.

For instance, a current through a wire makes a magnetic field around it, and the changing magnetic field creates an electrical field, which then creates a magnetic field, and so on. Are these fields pulling on the wire? If so, how exactly? Isn't every piece of the wire dx electrically neutral...

hmm i thought the path of a static observer in Schwarzschild spacetime was a Killing vector, since the metric doesn't change as one simply advances in time. https://physics.stackexchange.com/questions/214434/killing-vectors-in-schwarzschild-metric?rq=1

Follow up: It looks like — just going by my geometric intuition here — that Killing fields must have zero divergence. Can one please give an example of a vector field with zero divergence that is not a Killing field?

Thanks Peter, i think i'm getting a feel for it now. Like the way a set of particles in a stone move when the stone is either translated or rotated.

It comes up at the top of this search, but strangely not finding the quote in the cited PF thread itself...

I found this quote on a different PF thread: For parallel transport, you move the vector in a direction that is always parallel to the curve. For Lie transport, you move the vector so that its direction is always perpendicular to the curve. Thoughts? It sounds like this restricts the...

I don't have an intuitive feel for Killing vectors. Wikipedia says, " . . . more simply, the flow generates a symmetry, in the sense that moving each point of an object the same distance in the direction of the Killing vector will not distort distances on the object." That just sounds like...

Thank you both. Fascinating subject.

Doing a few calculations, i'm struck by this asymmetry: From the perspective of the inertial observer (A), the accelerating spaceship (B) has a speed which asymptotically approaches the speed of light, while from B's reference frame, A's speed asymptotically approaches zero. I haven't yet...