Could magnets be used for interstellar propulsion?

Jan Panteltje snipped-for-privacy@comet.invalid wrote or quoted:

A permanent magnet has a fixed magnetic dipole moment m.

It would feel a net force F = grad( m B ) in an inhomogeneous magnetic field B.

|Electromagnetic acceleration of permanent magnets 04078 (arxiv.org) |by SN Dolya · 2015

from there:

|The force of the magnetic dipole interaction Fz with the gradient of the |magnetic field can be written as follows: |Fz = m*dBz/dz, (1) |where m - the magnetic moment per mass unit, dBz /dz - the magnetic field |gradient.

However, in nature there are no fields that can be used to accelerate a spacecraft this way, so one would have to generate such fields.

Earth has a magnetic field, and nobody uses magnets to drag boats or aircraft around.

Sure they do. So it's hardly surprising some people believe it. It's at 1:17

You also need a large _gradient_ of magnetic field. (Unless you have a supply of magnetic monopoles :-))

What is that even supposed to mean?

What is that even supposed to mean?

Earth *is* a magnet. It is pushed by the magnetic fields of the sun and galaxies. That's what makes the earth go round the sun.

I’m expecting Dirk Bruere to phase in from his mystical magical dimension any minute.

Cheers

Phil Hobbs

Cool. Thanks for the laugh.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Earth has a very weak magnetic field. Consequently even near the poles the force will be too small to be of any practical use.

The torque on a dipole is sometimes used for satellite attitude control.

You can't control the direction of the force. In any case the magnitude of the force would probably down there with the light pressure from stars lightyears away.

And a dipole couples to the field gradient, not the field, so the effect would be vanishing**2ly small. (Or is that vanishing**3fly?)

Cheers

Phil Hobbs

One could use no fuel to drive from Boston to SF if you take only the downhill roads.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

It could be downhill both ways if you lived at the school. ;)

Cheers

Phil Hobbs

That's why they're worried about magnetic pole reversal. We'll start orbiting the sun in the opposite direction. Or maybe it will just make time go backwards. Who knows? Ed

It can at least makes time stand still. Did you know Joshua commanded the sun to stand still for 2 hours so he could finish his slaughter? He made all the virgin Amorite girls hold up their mirrors to reflect the magnetic field the other way, so the earth stopped spinning while his men finished slaughtering the rest of the Amorites. Then Josh's men ravished their new concubines. They were the sluttiest virgins.

It isn't. The magnetic fields around the sun are pretty erratic. Earth's rotation around the Sun isn't.

The earth is big and heavy and full of iron and stuff. It smooths out the fuzz in the sun's magnetism and keeps a lid on the magnetic typhoons. Otherwise the sun would be flipping its poles every day.

Nasa studies all this. Check there website.

They also said earth rotates around its axis, not the sun.

The sun doesn't have a single magnetic pole. It has lots of complicated magnetic structures in the solar corona, none of which are influenced by the earth - though magnetic storms in the solar corona can influence the earth.

I'm aware of their web-sites. You don't seem to understand what they are telling you.

The earth does rotate around it's own axis. It is also in an elliptical orbit around the sun.