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Comment by eig | Hacker News Reader

This video (https://sciencecast.org/casts/suc384jly50n) showing the Meissner effect should be the easiest to replicate: just send a sample to another lab and put it over a large magnet.

As far as I know, the only explanations for this occurring is room temp superconductivity, or a strong diamagnetism (which would also be very cool to see)!

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That video reminds me of the way pyrolytic graphite floats on strong magnets.

https://scitoys.com/scitoys/scitoys/magnets/pyrolytic_graphi...

https://youtu.be/Wk3seHNmNs8

Yep, that’s strong diamagnetism.

The common point being that it levitates, at room temperature (so no cryogenic fumes on the video), but that's exactly what you'd expect from a room-temperature SC… The big difference between your graphite video and the one from yesterday is that the later doesn't move, whereas the former never rests.

The problem with the video we see is that the sample never actually levitates - one side is touching the magnet. So a regular diamagnetic material, with enough weight on one side, would display the same effect.

In this video shortly after this moment you see something very similar looking with pyrolytic carbon: https://youtu.be/VC3r9-OaWes?t=133

It's true that pyrolytic graphite does this, but it's also worth noting that pyrolytic graphite is one of a very few materials that has such a strong conventional diamagnetism: the list includes pyrolytic graphite and metallic bismuth and ends there. I have actually searched the literature for such materials on a few occasions simply because they seem like they would make a fun decoration, and PG (and "highly oriented" PG) is pretty much the only one (bismuth is too dense).

Definitely. Discovering another material besides pyrolytic graphite that exhibits strong enough diamagnetism to levitate wouldn't get your name in the history books like room-temperature superconductivity would, but it would already be a major career-making discovery, with at least enough commercial value to launch a niche company. It would be very strange to tarnish your reputation with fraudulent, easily-refuted claims of superconductivity if you've already achieved such a breakthrough.

As far as I am aware you need multiple magnets to make this happen, just one will cause it to "fall" off. In the video it's just one magnet, and it doesn't try to "slide" away when it's moved past the edge of the magnet. That's a strong indicator of quantum locking.

I am not an expert in this field though.

https://www.imagesco.com/magnetism/graphite-levitation-kit.h...

https://scitoys.com/scitoys/scitoys/magnets/pyrolytic_graphi...

They don't show the actual field of the big metallic cylinder, so you can't rule out a situation as shown at the start of this video: https://youtu.be/D-tW8_SRW3g where two identically looking objects are revealed to have very different magnetic fields.

Whether it makes sense to say the multipole magnet is "multiple magnets" is a philosophical debate in itself.

I don’t know enough about this but shouldn’t the entire superconductor be floating above the magnet? Why is one part still attached (or maybe attracted) to the magnet?

Contamination/impurities or something else in it that's not superconducting?

A strange exposition video then, I would try to remove the part that wasn’t superconducting (the part touching the magnet) before I released this. A completely floating piece of this superconductor would remove literally all doubt.

You say to do WHAT to the best piece of sample they synthesized?

Scope of the claim. This is world changing. Shoot the first video, then get the dremel/pliers and cut that large bit off. It would be worth it, because if this works at all, then it's vital to prove it. We'd be having a very different discussion if that small piece was umabiguously floating and remaining locked in place.

> it's vital to prove it [asap]

Is it? What do they care if it takes other labs a week to reproduce?

But you don’t understand, people are being skeptics on the internet.

For one thing, because if you're throwing out a world-changing claim, you yourself would like to be sure it is what you think it is.

It's an obvious test to do, so it's quite surprising they didn't do it. Maybe they did and didn't film it, I don't know - but for the trouble of a couple of minutes of time, it's weird not to have it - especially if your method is reproducible.

Based on what I'm hearing, it sounds like they weren't able to produce a macroscopic ingot of the stuff, so it seems likely to me that the superconducting part is up at the end there. However, without further explanation, I'm disinclined to take that video (fantastic as it seems) to be conclusive evidence of anything.

The original preprint mentions bulk samples, but I’m not sure what size they were. I would guess at least a few millimeters scale, but really bulk just mostly means “not a thin film”

As an undergrad I helped with research on quasars, where reasonable precision was solar mass orders of magnitude and tens of parsecs, and the periodic table was Hydrogen, Helium, and "metals". Then I switched to condensed matter physics for grad school, where "bulk" meant "a scale visible to the naked eye under very good conditions".

The dichotomy makes me laugh.

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