[Hannah LS (OP)]

Leith asks:

If I hold up a weight with my arms it takes energy to hold it up against the force of gravity. The same is true for electromagnets. So if I take a natural magnet and stick it to the underside of a metal shelf it sticks, and a year from now it will still be sticking... Where does the energy come from to counter the effects of gravity?

What do you think?

[Bored chemist]

A shelf can hold up a weight without using energy so it's clear that no energy is strictly needed.
The fact that your arms or an electromagnet need energy to do it just shows that they are an inefficient way to  hold stuff up.

A magnet doesn't suffer from that inefficiency, and so it doesn't expend  energy  while holding things up.

[Kryptid]

The only reason it takes energy for you to hold up an object with your arm is because your muscles require it in order to maintain a retracted state. Such would not be true for, say, a mannequin holding up the same object. Strictly speaking, energy is not required to hold an object up against a force: only another force of equal and opposite magnitude is.

[yor_on]

Magnetism is produced by unpaired aligned electrons in a magnetic medium. As they combine they produce a magnetic field. Taking a wire and moving it inside this magnetic field will produce a current (electricity). So it's not only just a magnetic field, It's EM. And it's frame dependent. https://www.livescience.com/38059-magnetism.html

As for if spin is a energy?
I think so, could be wrong though.

[evan_au]

If I hold up a weight ... it takes energy to hold it up against the force of gravity

If I remember my high-school Physics class correctly, if you lift a 1kg mass (9.8 Newtons force) up by 2 meters against gravity, you have expended energy as indicated by the equation E=FS = 9.8 x 2 = 19.6 Joules
- Where E is the energy in Joules
- F is the force in Newtons
- S is the distance, in meters

In high-school Physics, holding the 1kg mass above your head at a constant height takes no energy, regardless of whether it is for a for a minute or a year. In this case S=0, and E=FS = 9.8 x 0 = 0 Joules.

Similarly, in Physics class, moving a piece of iron relative to a magnet takes energy, but holding it at a constant distance from a magnet takes no energy. You can use the same equation E=FS, but since the force F changes significantly while you move it over the distance, you have to use integration rather than multiplication, which takes it beyond the high-school Physics classroom, and into the university Maths classroom.

If I hold up a weight with my arms

You just left the high-school Physics classroom, and moved into the high-school Biology classroom.

Different Answer!