Neodymium magnets are immensely powerful--so much so that getting one accidentally stuck up your nose may require a hospital visit.
Grant Slatton, a software engineer, used the magnetic force of a set of magnets to good effect to build a levitating bed. When the magnets are set in opposition to each other--five in the frame and five in the base--they can hold his bodyweight in the air.
The guidewires keep the bed hovering in the proper spot. The magnets, Slatton explains, must be very close to each other to maintain repulsion.
Slatton appreciates the fame the bed brought him when he first shared it on the internet in 2012. But he also notes that the bed wasn't particularly comfortable.
It's very easy to fool oneself by accident. You knew the magnets were there, for example, so it wasn't even single-blinded. The magnets you can get from a hardware store have a field through your body which is far smaller than in an MRI, which can pull metal objects out of someone's grasp.
Some people manage to sleep while having an MRI scan, which is 3 T or higher.
From what I gather, there was a 2015 paper claiming the worm C. elegans is magnetosensitive, but it has not been replicated. ("We find that under these conditions the worms moved randomly on horizontal plates placed either on top of a strong neodymium magnet or within a homogenous Earth-strength horizontal magnetic field.")
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