galilette

@galilette@mander.xyz

• ⁨Comment⁩ on ⁨Physicists trap electrons in a 3D crystal for the first time⁩ ⁨⁨11⁩ ⁨months⁩ ago⁩:

  “Trapping electrons in a crystal” is such a nonsensical way of conveying the idea of a flat band. Most isolated crystals trap all the electrons they have inside of them, or else the world will be full of free roaming electrons!

• ⁨Comment⁩ on ⁨Sunday Funday Puzzle - Electromagnetism⁩ ⁨⁨1⁩ ⁨year⁩ ago⁩:

  current carrying wire of finite length

  Well I suppose a cheesy way of putting this is that there is no such thing as a “current carrying wire of finite length”, by itself.

  To expand, just because one can calculate the contribution to the magnetic field at some spatial point from such an object, doesn’t mean it is the sole source of the field in a theoretically consistent manner. If you complete the “loop” with two semi-infinite horizontal wires, and another vertical wire at infinity (assuming it has an emf there to power the circuit), then the field will change due to the two horizontal wires. This construction however breaks rotational symmetry around the original wire (so you’ll not be able to compute the loop integral simply as B times circumference), and in order to restore that, instead of just two horizontal wires, you’ll have to have infinite such pairs in all radial directions (like a squeezed coaxial cable). Anyway, I guess the point is after “completing the circuit”, the “paradox” will no longer be there.

• ⁨Comment⁩ on ⁨The world's largest chipmaker promised to create thousands of US jobs. There are growing tensions over whether US workers have the skills or work ethic to do them.⁩ ⁨⁨1⁩ ⁨year⁩ ago⁩:

  You guys do know the affordability of the chips you’re using to comment on this is a direct consequence of TSMC “efficiency”, right?

• ⁨Comment⁩ on ⁨[deleted]⁩ ⁨⁨1⁩ ⁨year⁩ ago⁩:

  Mind you, the DFT calculation from the Griffin paper is not a proof of LK 99 being a superconductor in any way. What it showed is the (potential) formation of flat bands near the Fermi surface. Band dispersion is associated with the kinetic energy of the electrons, so materials with flat band at the Fermi surface is more susceptible to interaction effect (and strong interaction causes all sorts of nonintuitive quantum effects). I’m not a DFT expert in any sense, but from what I’ve heard, it is quite easy to “tune” your model to produce narrow (the limit of which being flat) bands from substitutions (e.g. the Cu substitution in this case) and such, which don’t necessarily lead to superconductivity.

  So I’ll take the DFT papers (there are quite a few now) as saying, “hey you want some flat band? Here’s some. We’ve done our part. Now some other theorist, do your magic and conjure up some superconductivity”. It’s a cog in the full picture, if there is a full picture

• ⁨Comment⁩ on ⁨What Time Dilation ACTUALLY Is In Relativity (Hint: It has nothing to do with time)⁩ ⁨⁨1⁩ ⁨year⁩ ago⁩:

  Step 1: “Explains” relativity with Doppler effect Step 2: proceeds to complain others confusing relativity with Doppler effect