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From: ram@zedat.fu-berlin.de (Stefan Ram)
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Subject: Re: Could magnets be used for interstellar propulsion?
Date: 1 Feb 2026 12:57:43 GMT
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Jan Panteltje <alien@comet.invalid> wrote or quoted:
>So that makes me wonder if a spacecraft with just a permanent magnet
>that you can move to give you a force in the direction you want to go

  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.