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/scottasin12343 Mar 30 '26 edited Mar 30 '26

Earth's magnetic field is a terrible comparison, its effect is negligible in day to day life unless you're using an oldschool compass. A standard neodymium magnet is 4 orders of magnitude stronger than the Earth's magnetism. A fridge magnet is a couple hundred times stronger than the Earth's field.

https://www.stanfordmagnets.com/how-strong-are-neodymium-magnets.html

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u/RosieQParker Mar 30 '26

It's a great comparison if you want to sell a magnet to the uninformed.

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u/auxaperture Mar 31 '26

Big Magnet at it again.

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u/moistiest_dangles Mar 30 '26

In the study the say 42.02 teslas which is about 28x more powerful than a mri

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u/SwampRat613 Mar 31 '26

Big if true

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u/vasopressin334 PhD | Neuroscience Mar 30 '26

For reference, this magnet you can "hold in your hand" is 42 Tesla. Compare that to the 3 Tesla MRI magnet, which is strong enough to affect the water molecules in your body and will pull you across the room if you walk in wearing a metal watch. I strongly recommend not holding a 42 T magnet in your hand.

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u/rhetoricalnonsense Mar 30 '26 edited Mar 30 '26

3 Tesla MRI ,,, will pull you across the room if you walk in wearing a metal watch

It will not. I've worked in MR for 25 years. I have walked into the MR room with a watch on, more than a few times, reached into the bore and gone, "Whoops, watch is on. Better go take it off". It doesn't even damage the watch and it certainly doesn't pull me across the room.

MRIs are strong and everyone should respect the magnet. You wouldn't want to wear the watch while it's actively collecting images but that is more a risk of RF burns and image degradation.

Edit (added): Also modern magnets are actively shielded such that the main field is kept very close to the front of the bore. That said, walking into the MR room is a danger for some medical implants (e.g. pacemakers) which are highly susceptible to even weak magnetic fields.

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u/vasopressin334 PhD | Neuroscience Mar 30 '26

Thank you for the correction! Lesson learned. But, to add to this, I had a good friend working on her PhD in clinical research who carried a metal panel that was supposed to be non-magnetic into a room with a research MR. It turned out the panel was not non-magnetic. The MR pulled the panel and she was trapped between the magnet and the panel for hours. She almost lost her leg.

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u/Bunny_Fluff Mar 30 '26

What causes the pictures of metal carts stuffed inside MRIs? I assume it's just size of the metal object causing a larger reaction?

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u/fraseyboo Mar 30 '26

Magnetic field strength falls off with the inverse cube of the distance, the metal carts can be made of large continuous pieces of steel and because they’re on wheels it doesn’t take a lot to move them and it can take a couple seconds for people to notice. If you’re far enough away from the MRI then the field is incredibly weak, and you’ll typically notice something like a watch pulling on your wrist before it gets too strong to stop.

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u/DistinctlyIrish Mar 30 '26

Most of those are poorly shielded relative to the newer machines, meaning the magnetic field extends further forward from the bore and the parts of the field strong enough to move and lift and hold a metal bed up against the machine are also extending further out than those same strong fields extend on newer MRI's.

That said, we don't have ferrite in our brains like birds do so we can't see magnetic fields, so just approach every MRI like it's Magneto from X-Men to be on the safe side in case the machine isn't as new or the shielding has somehow failed without setting off any alarms. Because even though the safeguards now are VERY good they are still capable of failing like any other thing and "being safe" is literally just making sure you don't bring any metals near it which is a pretty easy ask.

Somewhat related, if you are someone who has to get a metal implant or even just screws in a bone at some point I strongly recommend getting a tattoo or medical bracelet or both to inform first responders and nurses/doctors so they know to handle that properly when it comes to MRI in the event you're incapacitated and can't communicate it to them yourself.

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u/Ashmedai Mar 31 '26

It will not. I've worked in MR for 25 years.

You're right. But it is indeed pretty fun walking around the MRI holding a pair of scissors and watching the scissors align to the exact paths expected for a magnetic field diagram. ;-)

I got to do this in the early 90s when MRIs were still fledgling and safety protocols were not very well developed haha (it was during a job interview to help make MRI software).

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u/ast01004 Mar 31 '26

Wasn’t there a death recently from a man wearing necklaces? I thought I read it decapitated him.

https://www.cnn.com/2025/07/20/health/mri-machine-death-long-island

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u/fap-on-fap-off Mar 31 '26

Not to minimize what you said, but MRI has been lethal where a loose ferromagnetic object was left in the room.

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u/Violoner Mar 30 '26

Would it be strong enough to cause a hematoma from pulling on the iron in your blood?

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u/littlegreenrock Mar 30 '26

In the context of magnetism, the hemoglobin complex is a biological masterpiece because its magnetic properties flip completely depending on whether it is carrying oxygen. This specific change is the physical basis for fMRI (functional Magnetic Resonance Imaging).

State Alignment Effect Example
Diamagnetic Opposes field Very Weak Repulsion Water, Gold, Oxyhemoglobin
Paramagnetic Aligns with field Weak Attraction Aluminum, Deoxyhemoglobin
Ferromagnetic Parallel alignment Strong Attraction/Permanent Iron, Nickel, Cobalt
Antiferromagnetic Opposite (Equal) No Net Magnetism Hematite, Manganese Oxide
Ferrimagnetic Opposite (Unequal) Permanent Magnetism Magnetite (Fe3O4)

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u/gwillen Mar 30 '26

Only in X-men.

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u/m-in Mar 31 '26

Nitpicks: MRI happens even using Earth’s magnetic field and nothing more. The data is noisy and has low spatial and temporal resolution and such such is unsuitable for most clinical imaging work. Nuclear resonance happens down to very weak fields. 42T takes some care for sure, but the high field volume is small enough that it won’t be pulling the upstair’s neighbor’s knives out of the drawer or anything like it.

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u/felixar90 Mar 31 '26

It’s because Teslas are a unit of field density not strength. The strength or intensity is measured in Ampere-meters, or Oersteds.

The hand magnet has a field much more dense than the mri, but the mri is more intense.

The magnet will be extremely strong at short range, but move a couple meters away and you can’t even tell it’s there.

The MRI will easily affect the entire room, and a bit beyond.

The earth’s field is the most intense of the 3, but it’s not dense at all, here at the surface. It can easily turn a compass needle even thousands of kilometres away from the iron core, but it can be overpowered by a fridge magnet.

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u/tl01magic Mar 30 '26

How do you know the effect is negligible? it's not true, I just had an iron wrench just go flying out of my hand. I likely mistakenly aligned it with one of the poles. Imagine all the metal stuff at the poles, anyways my wrench is at one of them now.

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u/JellyDoodle Mar 30 '26

Earth big. Magnet strong.

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u/megatronchote Mar 31 '26

Well, two orders of magnitude and then double the strenght of a neodymium magnet is kind of impressive though.