What causes magnetic repulsion and attraction?

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1. May 21, 2015

Prashan Shan

is magnetic repulsion and attraction is due to the bending of curvature of spacetime?

2. May 21, 2015

mrnike992

No. The bending curvature of spacetime causes gravitational attractive forces. The force of magnetic attraction and repulsion is attributed to one of the other four fundamental forces, the electromagnetic force.

3. May 21, 2015

Prashan Shan

thank you for replying. I saw on internet that magnetic lines are curved due to the bending of space time.

4. May 21, 2015

mrnike992

Well, electromagnetic waves follow the curve of spacetime, but this does not provide the forces of magnetic attraction/repulsion.

5. May 21, 2015

Staff: Mentor

This is true, but it's not what produces magnetic forces. Magnetic forces are present even where the curvature of spacetime is negligible.

6. May 21, 2015

Prashan Shan

then, can a strong enough magnetic field bent space time?

7. May 21, 2015

mrnike992

Not directly, no.

8. May 21, 2015

Staff: Mentor

Actually, yes, it can. Magnetic fields contain energy, and energy produces spacetime curvature. But "strong enough" turns out to be very, very, very strong indeed; to produce the same spacetime curvature as the mass of the Earth does, you would need a magnetic field of about 10 million Tesla throughout an entire volume of space equal to the Earth's volume.

9. May 21, 2015

Prashan Shan

ho much energy is required to bend space over a very small area.

10. May 21, 2015

mrnike992

Ah, I see. That makes sense. Then nothing does not bend spacetime.

11. May 21, 2015

Staff: Mentor

It's spacetime, not space, and how much energy is required depends on how much you want to bend spacetime, and over how small an area. In general it takes a lot of energy to cause measurable spacetime curvature; that's why we associate spacetime curvature, i.e., gravity, with large masses, since rest mass is the most concentrated form of energy we know. But even then, as you can see, it takes a lot of mass--the size of a planet--to produce significant spacetime curvature.

12. May 21, 2015

Prashan Shan

when a magnet dropped into a copper tube it produces induced current which opposes the further motion of the magnet and produces a time dilation effect (the magnet seems to move slowly) right?
but i thought that it is due to real time dilation which is caused due to the bending of space time around the magnet. it may seem silly.

yes more energy is required to bend space time with magnet but what if space time is really bent when one magnetic field crosses another magnetic field.

13. May 21, 2015

mrnike992

That's not time dilation. That's simply magnetic force working in the opposite direction of gravitational forces, resulting in a smaller magnitude of acceleration.

14. May 21, 2015

Staff: Mentor

As I said before, spacetime curvature is caused by the energy in a magnetic field (just as by any other kind of energy). Whether one magnetic field is crossing another is irrelevant; it's the energy in the fields that matters.