B Do Permanent Magnets Bend Spacetime? Basic Thread

[Dante Meira]

Basic level thread here. If gravity "bends" the spacetime continuum, do a strong permanent magnet bend spacetime too? I'm no physicist, I'm layman, and I just don't know how this "bending" of spacetime works when a Jumbo jet is in free fall from 10 thousand meters high, pulled by Earth's gravity. If there is spacetime "bending" in the Jumbo jet case, is there spacetime "bending" involved when two massive neodymium permanent magnets attract each other from a distance of more than 10 centimeters?

Sorry if the question is stupid and makes no sense, I'm just a layman with no significant background in Physics.

 

[phinds]

Basic level thread here. If gravity "bends" the spacetime continuum, do a strong permanent magnet bend spacetime too? I'm no physicist, I'm layman, and I just don't know how this "bending" of spacetime works when a Jumbo jet is in free fall from 10 thousand meters high, pulled by Earth's gravity. If there is spacetime "bending" in the Jumbo jet case, is there spacetime "bending" involved when two massive neodymium permanent magnets attract each other from a distance of more than 10 centimeters?

Sorry if the question is stupid and makes no sense, I'm just a layman with no significant background in Physics.

There is no "bending" involved, actually. That description comes from pop-science's insistence on applying Euclidean geometry and Newtonian gravity to a regimen in which they are not applicable. Space-time is described by General Relativity pseudo-Riemann geometry, in which things travel on the Riemann equivalent of straight lines. We call these "geodesics" and when they are described with Euclidean geometry, they are curved, which is where the "bending" and "curving" terms come from. This geometry of space-time is dominated by gravity. Objects in free-fall under gravity travel along geodesics so in true (Reimann) terms, they are going in straight lines but in Euclidean terms they are (usually) going on curved lines.

Magnetism is not gravity but it does have some similar effect on spacetime because of its contribution to the stress energy tensor in its region (in addition to the contribution of the mass of the magnet). That's more complicated than I can explain.

 

[Vanadium 50]

No. It is a different phenomenon altogether.

 

[phinds]

No. It is a different phenomenon altogether.

So this:

https://www.scientificamerican.com/article/do-electric-charges-and-m/

for exampe, is wrong or am I misunderstanding it?

 

[PeroK]

I think the key point is that a charged particle moves differently from an uncharged particle in a magnetic field. Their motion due to the gravitational effects of the physical magnet and any gravitational effects of the stress-energy of the electromagnetic field - which are likely to be negligible - are different from the motion of the charged particle due to the Coulomb force on it.

I.e. the Coulomb force is not explained by spacetime curvature.

 

[Dale]

If gravity "bends" the spacetime continuum, do a strong permanent magnet bend spacetime too?

Yes, but their gravitational effect is very very very very small compared to their magnetic effect.

 

[phinds]

Yes, but their gravitational effect is very very very very small compared to their magnetic effect.

Dale, I assume you mean here that their gravitational effect on space-time is very small compared to their magnetic effect on other magnetic material, not that their gravitational effect on space-time is small compared to the magnetic field's effect on space-time, yes?

 

[Dale]

I assume you mean here that their gravitational effect on space-time is very small compared to their magnetic effect on other magnetic material,

Yes. I wanted to make sure that he didn’t think that the minuscule curvature of spacetime is responsible for holding his kids artwork on the refrigerator door