# Vacuum cannot be magnetized?

by Hardik Batra
Tags: magnetized, vacuum
 P: 108 Why can't the vacuum be magnetized? Another question... Magnetic field induced in a substance, depends on Magnetic intensity (H) and Magnetization (M). If H is too much strong then what happens in a substance.
 Homework Sci Advisor HW Helper Thanks P: 13,052 1. No magnetic zones. 2. depends what you mean by "too strong".
P: 108
 Quote by Simon Bridge 2. depends what you mean by "too strong".
I don't know.
But in my textbook written as,
if H is not too much strong, then the magnetization M induced in the substance is proportional to magnetic intensity H

M = XmH

 Quote by Simon Bridge 1. No magnetic zones.
means magnetic field won't produced in vacuum due to magnet.

Homework
HW Helper
Thanks
P: 13,052
Vacuum cannot be magnetized?

 But in my textbook written as, if H is not too much strong, then the magnetization M induced in the substance is proportional to magnetic intensity H
Oh right - the text book is making a weak-field approximation.
##M\propto H##

When H is "too strong" then the proportionality does not hold and things get complicated.

Its a bit like Hook's law only works so long as you don't exceed the elastic limit.

 means magnetic field won't produced in vacuum.
... no: it means that the vacuum itself cannot be magnetic, although objects in the vacuum can be.
Consider: what is the definition of "a vacuum"?

Note: it is possible to have magnetic fields in a vacuum.
P: 108
 Quote by Simon Bridge Oh right - the text book is making a weak-field approximation. ##M\propto H## When H is "too strong" then the proportionality does not hold and things get complicated. Its a bit like Hook's law only works so long as you don't exceed the elastic limit.
I want to know if H is too strong then what kind of complication occur in a substance.
 P: 1 Would it not be considerably correct to state that "vacuum" rather then beeing "empty of matter" is "full of EM-fields"? Hence creating a more permanent magnetization (which is mostly characterised by the crystal structure, molecular alignments and the elements present in the substance beeing magnetized) requires matter, which by definition is not considered in the studied system when studying "vacuum". However, the effect of magnetism and the definitions of para-, dia- and ferro-magnetism might not match for much longer, considering freaky results of experiments with DNA and quantum systems are teaching us. Hence, the vacuum clearly does not seem to be empty considering that the EM-fields contain potential energy that can interract with matter. (at least no more empty then the "space-time curl" related to matter, beeing reponsible for the effect of gravity) Saturation is normally occuring in physical systems and at "extreme energies" systems tend to encounter relativistic effects in addition to this. So to answer the orignial question of why vacuum cannot be magnetized I would like to form a answer where the definition of magnetism and vacuum are not really compatible as described above. Edit: About what happens in the material when the field strength becomes high I believe that the resulting eddies and small field variations create a more "turbulent" environment within the field. And if no negative feedback loop exist within the system (as I believe the case of magnetic fields in the vacuum is) small fluctuations will spread easily. If anyone wants to comment, please do!
Homework
HW Helper
Thanks
P: 13,052
Welcome to PF snedkliv;
 Would it not be considerably correct to state that "vacuum" rather then being "empty of matter" is "full of EM-fields"?
Classically, a vacuum is "nothingness": the container for other things - so a vacuum "full of EM fields" is not a vacuum. The vacuum is the bit "in between" the fields.

However - take a closer look at the Feynman diagram for a vacuum.

Note: a full reply requires an answer in terms of Field Theory - the short answer is that there is no way to align the magnetic terms in the Feynman sum that corresponds to a vacuum so as to make a magnet out of it.

@Hardik: what happens depends on the material.
The relationship between M and H stops being linear ...
For the general case: http://hyperphysics.phy-astr.gsu.edu...ids/magpr.html

 Related Discussions Introductory Physics Homework 1 Classical Physics 2 Advanced Physics Homework 1 Advanced Physics Homework 3 Advanced Physics Homework 3