# Does a magnet's field become stronger or weaker in a vacuum?

This article seems to indicate that a magnet (atleast magnetite, it may not apply to rare earth magnets) weakens when subjected to extremes of pressure. This is purportedly the result of a decrease in electron spacing ... or so I understand from the article.

Does then a magnet's influence change in a vacuum? Does the magnet appear to become stronger in a vacuum? Or is the converse true again?

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Why the tag 'electromagnetism'? –  Everyone Nov 18 '12 at 9:31
One thing to keep in mind is the huge range of pressure scales involved. Their experiments are at about $100,000\textrm{ atm}\approx 10^{10}\textrm{ Pa}$. Normal atomospheric pressure is $1\textrm{ atm}\approx 10^{5}\textrm{ Pa}$, and while we can't really make a strict vacuum in a lab, we can make Ultra-high vacuum, at pressures of $10^{-7}\textrm{ Pa}$. While John Rennie is most probably correct, one must always be wary when describing phenomena ranging over 17 orders of magnitude. –  Emilio Pisanty Nov 18 '12 at 12:30

## 1 Answer

The article describes a change in electronic structure that occurs at high pressure. The article doesn't go into a lot of detail about the nature of the transition and the pressure it occurs at, but below the transition pressure you'd effect the pressure to have little effect. So there would be no difference in the magnetic field of magnetite between a pressure of 0 an 1 atm.

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