I've got a challenging question for the physicists among you.
I know that there is no such thing as a real 'permanent' magnet.
Like anything else in this physical
universe, the magnetic-energy contained
within a 'permanent' magnet will eventually weaken, fade & disappear.
So how long will the magnetic-energy
in a so-called 'permanent' magnet last?
For example: Take an 11Ib[5kg] 'permanent' magnet and stick it onto the bottom of an iron-girder [against the pull of gravity]. How long will that
'permanent' magnet cling to the bottom
of that iron-girder without outside
magnetic interference?
Jacob