A Snapshot of Foundational Attitudes Toward Quantum Mechanics

I dont get all that caught up in the issues of foundational questions of quantum mechanics; I think, for example, that the interpretations are bridges to understanding, so while I’m happy to cite the Copenhagen interpretation, I’ll also mention many-worlds if that helps — I don’t feel locked into one or the other. (There are some, though, that don’t “feel” right to me and/or seem to have been discredited in some way, and I don’t call upon them. I’m also not nearly as familiar with them). I don’t think you’re going to solve many of these foundational problems unless they aren’t truly foundational, in which case you then have to wrestle with the issues one level down.

Regardless, I think this “snapshot” is interesting, in part because others do spend more time on these issues. Also for the author and respondent comments on many of the questions.

via zapperz

One thing that would have been useful, I think, is a calculation in support of this, even if it’s just an order-of-magnitude one, to tell us if this is reasonable. The size of the spot (maybe a cm?) gives you a bound on the uncertainty of the transverse momentum. It’s green light (probably 532 nm) and the screen is of order a meter behind the slit. That tells us what the transverse component of the momentum should be — the momentum of the photon multiplied by the sine of the angle (or just the angle, in the small-angle approximation, which is around 0.01 radians)

So the uncertainty of the momentum is around 0.01 of the momentum, given by \(h/lambda\), so Planck’s constant drops out when we pop this into the uncertainty relation. Rearranging the equation tells us that $latexDelta{x} > frac{lambda}{4pitheta}$ or that we shouldn’t see this effect until the slits are separated by less than about 10x the wavelength of the light — which is around what we expect just from experience in diffracting light, that it only becomes an important consideration as you approach the wavelength of the light.

How Do You Make Negative Temperatures, Anyway?

There’s a also an explanation of negative temperatures in spin states

Well, sort of.

Optical wormholes: punching virtual tunnels in space via metamaterials!

A thought experiment for the relativity skeptics

An interesting thought experiment that shows how general relativity must hold, though I doubt it will work on the crackpot demographic, as it’s proof-by-contradiction, and ends up with a perpetual motion machine as the contradiction. If you think those are real, the proof doesn’t work. And also that nobody expects the Spanish Inquisition nothing works on the crackpot demographic.