Successful room temperature ambient-pressure magnetic levitation of LK-99

Post by happytiger » Fri, Aug 04, 2023, 8:30 PM UTC

Al-Khwarizmi wrote: post #798

shortrounddev2 wrote: post #784

Earlier quoted context omitted.

There is intense pressure to publish as many papers as possible at Chinese universities. This has led to a big problem of faked or just bad research papers coming out of China, so people are generally skeptical of them

This is a quite biased view. As a non-Chinese scientist, I can attest that there is intense pressure to publish as many papers as possible pretty much everywhere , and this leads to a problem of bad research across the world. China may be among the worst offenders in this respect, but the particular thing the OP is asking about doesn't strike me as a Chinese-specific thing at all. I see non-Chinese scientists rushing…

Post by octacat » Fri, Aug 04, 2023, 8:56 PM UTC

dontwearitout wrote: post #60

cypherpunks01 wrote: post #21

Why are folks trying to prove that this material is a superconductor in roundabout ways, like levitation, dimagnetism, etc? What is the reason they don't just test to see if electrical current flows without resistance? Surely there is something I am missing here.

My understanding is that synthesis of the exactly right crystal structure is very hard (for every 10 lead atoms, 1 - the exact right one - needs to be substituted with copper), so the samples are small and inhomogeneous. As a result measuring resistivity won't be illuminating until large amounts of perfect material can be produced.

Post by hwillis » Fri, Aug 04, 2023, 9:25 PM UTC

XorNot wrote: post #408

hwillis wrote: post #383

Earlier quoted context omitted.

You can't get CT scans very often, because they hit you with large doses of ionizing radiation. Ultrasounds are low-resolution spotlights; you shine them at a particular spot to diagnose something specific. With this you could get an MRI at your annual checkup. You could diagnose all number of diseases like that, not to mention 95% of cancers. Each year your scan is automatically compared to the previous year, and an…

> We might eventually transition away from AC power entirely. This is actually a really good point I hadn't fully considered, but it's right: the primary reason we use high voltage anywhere is because it minimizes resistive losses (and the reason we use AC is because it's easy to transform between voltages). But most of the stuff in my home doesn't need high voltage - it's all running at 5V or 12V. Or it's a motor wh…

Post by dotancohen » Fri, Aug 04, 2023, 9:44 PM UTC

Sharlin wrote: post #876

pmontra wrote: post #870

Earlier quoted context omitted.

Noob question: if whatever is happening is strong enough to raise one of the ends of the sample, why doesn't raise both? After all gravitation is many order of magnitudes weaker than electromagnetism. Did they calibrate the setup to closely match the gravitational force on the sample? Why not push a little more and make it fly up the the cap of the container?

Magnetic force scales as 1/r^3, not 1/r^2 like gravity. That's why your standard issue fridge magnet measurably attracts stuff only from a very close distance, but when it does, it easily counters the gravitational attraction of the entire planet¹. This 1/r^3 relationship can be derived easily enough by integrating, but essentially it's because magnets are dipoles and the farther away you are, the smaller the apparen…

  > Magnetic force scales as 1/r^3, not 1/r^2 like gravity

Post by azeirah » Fri, Aug 04, 2023, 10:03 PM UTC

bglazer wrote: post #873

kevstev wrote: post #760

Earlier quoted context omitted.

Last year I read The Double Helix and The Code Breaker within a few months of each other, and what really stood out to me is that while we celebrate the first person who discovers something, in reality there were several teams all racing to the finish line, and were sometimes days or only even hours behind in presenting their findings. Yet only one team gets the accolades and their names in textbooks, the others are…

Another example that might be of interest is the use of neural networks in Monte Carlo Tree Search. In 2017 there were two papers published showing how effective the combination of NN’s and MCTS are for planning in board games. One is an algorithm called ExIT published by Anthony et al, it showed excellent performance on a somewhat obscure board game called Hex. The authors using a typical academic lab setup to achie…