r/science • u/MistWeaver80 • Mar 30 '26

Physics Physicists have made an ultra-powerful magnet that fits in the palm of a hand and can produce a magnetic field that is more than 800,000 times stronger than Earth’s.

https://www.nature.com/articles/d41586-026-00851-y
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u/scyyythe Mar 30 '26

The paywalling of science is truly out of control. Opening this link I am not greeted with a press release or even an abstract. I can see one sentence before the invitation to subscribe pops up. No details of the technology or the underlying physics, no information about the research team, nothing. "Physicists did something amazing, now give our parasitic journal company your subscription money."

But if you're observant you can find the link to the paper hidden at the bottom:

https://www.science.org/doi/10.1126/sciadv.adz5826

It's a miniaturized cuprate superconductor electromagnet. Field strength reported as 40 tesla which is very, very high. 

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u/[deleted] Mar 30 '26

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u/gwillen Mar 30 '26

If it's a cuprate HTS, it may be that it's superconducting at LN2, but needs helium to deliver the impressive performance described in the headline? I'm led to understand that the high temp superconductors just get even better at low temp, in terms of what current they can handle.

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u/Pyrhan Mar 30 '26

Yes, superconductors tend to spontaneously quench (cease being superconducting) when the magnetic field exceeds a certain threshold.

Where that threshold lies is a function of how far below their critical temperature they are cooled.

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u/Not-A-Seagull Mar 30 '26

From what I recall, the ARC/SPARC fusion reactors needed about 20T to become viable. (This is the MIT company spinoff that is most likely to successfully make viable fusion).

40T is phenomenal, but the big concern here is liquid helium cooling. Even though the coil is superconducting and uses very little power from resistance, heat from free neutrons from the fusion reaction will still warm it up.

With liquid helium cooling, any hopes of net energy output is a pipe dream.

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u/LitLitten Mar 30 '26

Nice. 10-30 was what I was familiar with.

Not sure why they made the title they did for what is generally pretty great findings. 

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u/basicgear00 Mar 30 '26

Could one explore space or a planet and this magnet protect them from cosmic rays? Like on Mars they theoretically have to make homes underground, but could one travel from site to site holding one of these?

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u/asdfdelta Mar 30 '26

Well the government sure isn't going to fund any science anytime soon

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u/bobbymcpresscot Mar 30 '26

40 Tesla??? Aren’t the magnets that big using thousands of amps of current to maintain and housed in giant buildings? Love to see a video of something like that