Does magnetised material lose weight?

Question

I've had argument on a forum about this. People think, that:
if the same object is magnetised, it has less energy. so by $E = mc^2$ it weighs less than an object that is not magnetised (hence spin of its particles is chaotic).

I've thought about experiment :)

Let's say we have square of 4 protons and another square of 4 antiprotons. If we magnetise each square and annihilate them, do we get the same energy that we would get if only the antiprotons were magnetised?

Carl Brannen · Answer

(1) Magnetized objects typically have higher energy than before they were magnetized. There is energy in the magnetic field, and the magnetic field for a magnetized object is larger.

One way to see this is to imagine a large collection of tiny magnets. If you piled them into a mound they wouldn't organize themselves into all pointing in the same direction. Instead, they'd energetically prefer to be pointing in random directions so their magnetic fields cancel better.

(2) So magnetizing an object increases its energy and therefore increases its mass. But with the usual magnets available to mankind, the change in mass is so small as to be undetectable.

Markoul11 · Answer

Since gravity as far as we know today seems totally uncoupled to the other fundamental forces (although gravity is not a force but anyway emulates the effect of a force) we can safely say that no, magnetization will not affect the weight of the object. The degree of electromagnetic coherence thus magnetization of ferromagnetic or paramagnetic matter does not change the mass of an object and therefore its weight inside the gravitational field of the Earth for a given altitude and latitude remains unaffected.

Answered by Markoul11 on February 1, 2021

Does magnetised material lose weight?

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