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I wonder if other people who are getting on in years have this same kind of experience: thinking about something you thought you understood, and having a silly question pop into your mind (perhaps a question that could lead to interesting answers).
My silly question of the day is this: Given that a magnet's field arises from the alignment of the magnetic moments of elecrons with each other, and that these orientations tend to resist changes (e.g. precessing under external torque), then why don't they tend to stay aligned with "the fixed stars" rather than remaining aligned with the magnet's mechanical orientation as the magnet is slowly rotated? As a concrete example, take a perfectly spherical magnet. If you slowly rotate the magnet, how do the electrons "know" that the atoms are moving slowly around them and then decide to re-align their own magnetic moments (individually and collectively) so as to track the magnet's bulk rotation?
This question reminded me of a thread I started on the Einstein-deHaas effect, where some papers that I searched out seemed to indicate that Gilbert damping had a role to play in that effect.
Maybe something like Gilbert damping is at work when we rotate a magnet, causing the electrons' moments to track the bulk crystal's movements? At least, there should be some non-trivial interaction between electrons and crystal that is initiated when the magnet begins to rotate.
My silly question of the day is this: Given that a magnet's field arises from the alignment of the magnetic moments of elecrons with each other, and that these orientations tend to resist changes (e.g. precessing under external torque), then why don't they tend to stay aligned with "the fixed stars" rather than remaining aligned with the magnet's mechanical orientation as the magnet is slowly rotated? As a concrete example, take a perfectly spherical magnet. If you slowly rotate the magnet, how do the electrons "know" that the atoms are moving slowly around them and then decide to re-align their own magnetic moments (individually and collectively) so as to track the magnet's bulk rotation?
This question reminded me of a thread I started on the Einstein-deHaas effect, where some papers that I searched out seemed to indicate that Gilbert damping had a role to play in that effect.
Maybe something like Gilbert damping is at work when we rotate a magnet, causing the electrons' moments to track the bulk crystal's movements? At least, there should be some non-trivial interaction between electrons and crystal that is initiated when the magnet begins to rotate.