3 ms·
It would be cool, but there are no world-changing implications to a new diamagnet made of lead. It's just kinda neat if you find one.
by tux3 3y ago
It would be cool, but there are no world-changing implications to a new diamagnet made of lead. It's just kinda neat if you find one.
- fnordpiglet 3y agoI don’t know how that explains the resistances measurements though? Unless they’re complete fabrications don’t they imply superconductivity?
- tux3 3y agoI truthfully don't know. A few people suggested they might have measured an insulator, the threshold where resistance changes being the breakdown where current starts flowing. I'm skeptical either way, I think it's too early to say.
- fnordpiglet 3y agoI see. V=IR=0 means R can measure as 0, but they did measure small current. Presumably they know the voltage. That seems odd if they can’t measure the resistance accurately if their instrumentation is rated to measure that current.
- adrian_b 3y agoIt is not possible to determine that a resistance is exactly zero through direct measurement, because any kind of probes that can be used to contact the material will have a high contact resistance, which will vary from one probe contact to another. Even when the resistance is measured with a 4-point probe, the only conclusion that can be reached is that the resistance is smaller than the experimental error. However it should be possible to determine that the resistance is zero through various indirect effects, for instance by establishing a closed current in the material and verifying that it does not decrease in time. Even such experiments must be done carefully because some materials with unusual magnetic properties may behave apparently in a similar way to superconductors in some experiments, e.g. both a magnetized ferromagnetic material and a superconductor ring carrying a current will have a remanent magnetic field that is constant in time and in both cases the magnetic field will disappear when the temperature is raised above a threshold.
- fnordpiglet 3y agoThanks that’s interesting. If it’s so hard to determine if a substance is superconducting, does that mean many substances that are apparently but not quite superconducting have similar applicability? I.e., if you need superconductors for X application, can you not just put the substance in question in that application and observe if it works or not? Sorry for the dumb questions.
- highwaylights 3y agoMy understanding is that taking the paper at face value it seems like they’re saying the diamagnetism was an encouraging piece of supporting evidence beyond their other rationale for what they believe they’ve found. I’m not enough of a physicist (or one at all) to speak to that though so I guess I’ll just sit here wit ma popcorn for the next week with everyone else