Recent content by zen loki

Of course we can slow light down in a medium, but it is intriguing that it can be done in a vacuum. If the light is NOT in a medium, just how much can we slow it down?

In which case, what is the theoretical minimum vacuum group velocity of light? Can we just slow it down arbitrarily?

When we first learn of selection rules for atomic transitions, we learn that electrons have to change between states that differ in angular momentum by at most 1ħ, because photons have 1 unit of spin angular momentum. However, photons can have arbitrarily high integer quantities of orbital...

Bill, I can see that they are the same and I appreciate the clarity you have brought. And I can not think of any exceptions to what we have covered here. And while I understand the concept here, I am trying to push my understanding and see if there are any exceptions, or even if any exceptions...

Right, Tom, it is a consequence of SU(3,1) symmetry. I wonder if there is any possible conceivable macroscopic effect where a 360 degree turn yeilds a different result than a 720 degree turn. I say this, but I mean excepting things like Dirac scissors.

Thanks, Bill_K Since whenever we evaluate the wavefunction, we are always multiplying ψ by ψ* so any minus signs would be eliminated, of course. That is much more clear in my mind now. However, it is still curious that such an important symmetry for massive particles is absent in...

It is interesting that our elementary fermions have 1/2 spin, meaning it takes a full 720 degree rotation to bring them back to their original state and these fermions constitute ordinary matter, eg. quarks, and electrons. Classical nature, however, does not have a 720 degree symmetry, but...

First, it is entirely correct to think of unpolarized light as a sum of different polarizations, much like white light is the sum of all visible frequencies. No one polarization dominates, so we call it unpolarized. As for TM/TE/TEM this happens only in an electrically conducting cavity, thus...

It has long been predicted that gravitons will be spin 2. If that is true, then if we have a sufficient magnetic field, what is to stop us from recreating the Stern-Gerlach experiment and using a magnetic field to diffract them? Now, we have made very strong magnetic fields and to my...

Is there any evidence for quantum fermi-dirac distributions among neutrinos, besides the obvious fact about their spin? I was wondering how Pauli exclusion principle would work with a neutrino 'gas', and what kind of quantum numbers they could have. It has been expected that if we ever did...

I have a real stumper for you guys. We have an 7T (300 MHz) NMR in our lab that recently quenched – the superconductors went normal and we lost all our helium. That is can be pretty bad for a magnet, but we think ours got through it without significant harm. We have been getting it back up and...

Thanks, guys. The link with papers on mixing superconductors with different order parameters looks to be particularly useful.

I read that most type-2 superconductors have one quantum of flux (2*pi*h-bar/e) per flux filament (fluxon), but that a few have a different value (were fullerenes one of them?). I mentioned this to an professor I am doing some research for, and he challenged what I read. Now, I can't find what...