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Could magnets be used for interstellar propulsion?

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  Could magnets be used for interstellar propulsion? Jan Panteltje <alien@comet.invalid> - 2026-02-01 11:57 +0000
    Re: Could magnets be used for interstellar propulsion? ram@zedat.fu-berlin.de (Stefan Ram) - 2026-02-01 12:57 +0000
      Re: Could magnets be used for interstellar propulsion? Jan Panteltje <alien@comet.invalid> - 2026-02-01 16:44 +0000
        Re: Could magnets be used for interstellar propulsion? ram@zedat.fu-berlin.de (Stefan Ram) - 2026-02-01 16:55 +0000
          Re: Could magnets be used for interstellar propulsion? Ian <gay@sfu.ca> - 2026-02-01 16:19 -0800
            Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-02 05:35 +0100
            Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-02 05:40 +0100
              Re: Could magnets be used for interstellar propulsion? John Hasler <john@sugarbit.com> - 2026-02-02 08:02 -0600
                Re: Could magnets be used for interstellar propulsion? Jan Panteltje <alien@comet.invalid> - 2026-02-02 14:44 +0000
                Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-03 04:54 +0100
              Re: Could magnets be used for interstellar propulsion? john larkin <jl@glen--canyon.com> - 2026-02-02 07:20 -0800
                Re: Could magnets be used for interstellar propulsion? ram@zedat.fu-berlin.de (Stefan Ram) - 2026-02-02 16:30 +0000
                  Re: Could magnets be used for interstellar propulsion? ram@zedat.fu-berlin.de (Stefan Ram) - 2026-02-02 19:27 +0000
                Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-02 22:55 +0100
              Re: Could magnets be used for interstellar propulsion? Ian <gay@sfu.ca> - 2026-02-02 14:30 -0800
                Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-03 02:03 +0100
      Re: Could magnets be used for interstellar propulsion? ram@zedat.fu-berlin.de (Stefan Ram) - 2026-02-09 14:19 +0000
    Re: Could magnets be used for interstellar propulsion? Bill Sloman <bill.sloman@ieee.org> - 2026-02-02 00:41 +1100
      Re: Could magnets be used for interstellar propulsion? "Edward Rawde" <invalid@invalid.invalid> - 2026-02-01 09:58 -0500
      Re: Could magnets be used for interstellar propulsion? Jeremiah Jones <jj@j.j> - 2026-02-02 08:50 -0800
        Re: Could magnets be used for interstellar propulsion? john larkin <jl@glen--canyon.com> - 2026-02-02 09:28 -0800
        Re: Could magnets be used for interstellar propulsion? John Hasler <john@sugarbit.com> - 2026-02-02 11:49 -0600
          Re: Could magnets be used for interstellar propulsion? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-02-02 14:23 -0500
            Re: Could magnets be used for interstellar propulsion? john larkin <jl@glen--canyon.com> - 2026-02-02 12:39 -0800
              Re: Could magnets be used for interstellar propulsion? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-02-02 15:53 -0500
        Re: Could magnets be used for interstellar propulsion? John Hasler <john@sugarbit.com> - 2026-02-02 11:43 -0600
        Re: Could magnets be used for interstellar propulsion? ehsjr <ehsjr@verizon.net> - 2026-02-02 16:49 -0500
          Re: Could magnets be used for interstellar propulsion? Jeremiah Jones <jj@j.j> - 2026-02-02 20:42 -0800
            Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-04 20:11 +0100
              Re: Could magnets be used for interstellar propulsion? Jeremiah Jones <jj@j.j> - 2026-02-05 16:24 -0800
                Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-06 02:09 +0100
                  Re: Could magnets be used for interstellar propulsion? Jeremiah Jones <jj@j.j> - 2026-02-06 00:24 -0800
                    Re: Could magnets be used for interstellar propulsion? Bill Sloman <bill.sloman@ieee.org> - 2026-02-06 20:18 +1100
                Re: Could magnets be used for interstellar propulsion? Bill Sloman <bill.sloman@ieee.org> - 2026-02-06 18:07 +1100
                  Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-07 01:54 +0100
                    Re: Could magnets be used for interstellar propulsion? Jeremiah Jones <jj@j.j> - 2026-02-07 19:48 -0800
                      Re: Could magnets be used for interstellar propulsion? athel.cb@gmail.com <user12588@newsgrouper.org.invalid> - 2026-02-08 11:42 +0000
            Re: Could magnets be used for interstellar propulsion? john larkin <jl@glen--canyon.com> - 2026-02-05 16:48 -0800
          Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-04 16:36 +0100
            Re: Could magnets be used for interstellar propulsion? john larkin <jl@glen--canyon.com> - 2026-02-04 08:49 -0800
            Re: Could magnets be used for interstellar propulsion? John Hasler <john@sugarbit.com> - 2026-02-04 10:58 -0600
              Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-04 19:44 +0100
            Re: Could magnets be used for interstellar propulsion? john larkin <jl@glen--canyon.com> - 2026-02-04 18:21 -0800
        Re: Could magnets be used for interstellar propulsion? Bill Sloman <bill.sloman@ieee.org> - 2026-02-03 15:54 +1100
          Re: Could magnets be used for interstellar propulsion? Jeremiah Jones <jj@j.j> - 2026-02-03 20:35 -0800
            Re: Could magnets be used for interstellar propulsion? Bill Sloman <bill.sloman@ieee.org> - 2026-02-04 16:59 +1100
            Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-04 16:58 +0100
            Re: Could magnets be used for interstellar propulsion? ram@zedat.fu-berlin.de (Stefan Ram) - 2026-02-05 14:35 +0000
        Re: Could magnets be used for interstellar propulsion? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2026-02-04 16:23 +0100
    Re: Could magnets be used for interstellar propulsion? Colin <colin@example.invalid> - 2026-02-01 18:31 +0000
      Re: Could magnets be used for interstellar propulsion? Jan Panteltje <alien@comet.invalid> - 2026-02-02 05:54 +0000

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#895013 — Could magnets be used for interstellar propulsion?

I was watching some stuff of magnetic field lines in the universe
that I recoded last week from  zdfinfo.de
 https://www.zdf.de/dokus/geheimnisvolles-universum-100
It seems those are playing a much bigger role in the forming of galaxies and stars and the 'big bang' in the latest research.

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
could be used as a simple fuel-less drive?
Electromagnets should work too of course.

Any aliens here that have used it?

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#895014

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.

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#895017

>ram@zedat.fu-berlin.de (Stefan Ram)wrote:
>>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.
>
>

Using this:
 https://duckduckgo.com/?q=magnetic+filed+liunes+in+galaxies

gives as first reference:

Magnetic field lines in galaxies are patterns that represent the direction and strength of magnetic fields, typically following the spiral structure of the galaxy.
These fields play a crucial role in the dynamics of the interstellar medium and can influence star formation and gas flows within the galaxy.

 West Texas A&M University scholarpedia.org
Understanding Magnetic Field Lines in Galaxies
What Are Magnetic Field Lines?
Magnetic field lines represent the direction and strength of magnetic fields. In galaxies, these lines can be visualized as patterns that trace the magnetic forces at play within the galaxy's structure.

Structure of Magnetic Fields in Galaxies
Galactic magnetic fields typically consist of two components:

Large-scale Ordered Pattern: This mimics the shape of the galaxy, often forming spiral patterns that align with the galaxy's arms.
Small-scale Random Pattern: This component is generally stronger than the ordered pattern and is more chaotic in nature.
Measurement Techniques
Magnetic fields in galaxies are measured using various methods:

Optical Polarization: Light from stars is polarized by interstellar dust, allowing astronomers to infer magnetic field directions.
Radio Observations: Synchrotron radiation emitted by cosmic-ray electrons spiraling around magnetic field lines provides insights into the field's strength and structure.
Zeeman Effect: This method detects frequency shifts in polarized signals from molecules, revealing magnetic field strengths in molecular clouds.
Observations of Magnetic Fields
Recent advancements in radio telescopes, like the Very Large Array (VLA), have improved the ability to detect faint magnetic fields in distant galaxies.
Observations show that magnetic field lines can extend far beyond the visible structure of galaxies, sometimes reaching distances of up to 26,000 light-years.

Conclusion
Magnetic field lines in galaxies play a crucial role in their dynamics and evolution. 
They influence star formation and the behavior of interstellar gas, making them a key area of study in astrophysics.

 West Texas A&M University
 Wikipedia
Explore More

What are the effects of magnetic field lines on star formation in galaxies?

How do magnetic field lines influence gas flows in the interstellar medium of galaxies?

What are the different methods used to map magnetic field lines in galaxies?

----
This corresponds with what the zdfinfo.de  series, presented by 2 professors, mentioned.
So yes, there are magnetic field lines in the universe.

I know you can use 'gravity assist' to speed up spacecraft to reach further away planets for example
Why not use 'magnetic assist'?

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#895018

Jan Panteltje <alien@comet.invalid> wrote or quoted:
>What are the effects of magnetic field lines on star formation in galaxies?

  These natural magnetic fields in galaxies and their gradients,
  I think, are relatively weak. Over long timescales and over larger
  spatial regions, their effects can accumulate and become noticeable.
  But to drive a spacecraft, you'd need fields that are fairly strong
  at the location of the ship and at the moment the ship is there.

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#895021

Stefan Ram wrote:

> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>What are the effects of magnetic field lines on star formation in
>>galaxies?
> 
>   These natural magnetic fields in galaxies and their gradients,
>   I think, are relatively weak. Over long timescales and over larger
>   spatial regions, their effects can accumulate and become noticeable.
>   But to drive a spacecraft, you'd need fields that are fairly strong
>   at the location of the ship and at the moment the ship is there.

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

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#895023

Ian wrote:
> Stefan Ram wrote:
>> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>> What are the effects of magnetic field lines on star formation in
>>> galaxies?
>>
>>   These natural magnetic fields in galaxies and their gradients,
>>   I think, are relatively weak. Over long timescales and over larger
>>   spatial regions, their effects can accumulate and become noticeable.
>>   But to drive a spacecraft, you'd need fields that are fairly strong
>>   at the location of the ship and at the moment the ship is there.
> 
> You also need a large _gradient_ of magnetic field.

What is that even supposed to mean?

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#895024

Ian wrote:
> Stefan Ram wrote:
>> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>> What are the effects of magnetic field lines on star formation in
>>> galaxies?
>>
>>   These natural magnetic fields in galaxies and their gradients,
>>   I think, are relatively weak. Over long timescales and over larger
>>   spatial regions, their effects can accumulate and become noticeable.
>>   But to drive a spacecraft, you'd need fields that are fairly strong
>>   at the location of the ship and at the moment the ship is there.
> 
> You also need a large _gradient_ of magnetic field.

What is that even supposed to mean?

[Since you have not announced your F'up2 <news:sci.electronics.design> which
you should have, and this has more to do with physics that electronics
anyway, I am ignoring it.  F'up2 sci.physics instead.]

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#895026

Ian wrote:
> You also need a large _gradient_ of magnetic field.

 Thomas 'PointedEars' Lahn writes:
> What is that even supposed to mean?

https://en.wikipedia.org/wiki/Magnetic_moment#Force_on_a_moment
-- 
John Hasler 
john@sugarbit.com
Dancing Horse Hill
Elmwood, WI USA

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#895027

>John Hasler <john@sugarbit.com>wrote:
>>Ian wrote:
>> You also need a large _gradient_ of magnetic field.
>
> Thomas 'PointedEars' Lahn writes:
>> What is that even supposed to mean?
>
>https://en.wikipedia.org/wiki/Magnetic_moment#Force_on_a_moment

Thank you, nice link.

I have been experimenting with diamagnetic magnetic levitation a few years ago:
 https://panteltje.nl/pub/levitation_top_cut_img_3037.jpg
 https://panteltje.nl/pub/levitation_cut_img_3039.jpg

Magnetism is an interesting subject..
 https://en.wikipedia.org/wiki/Diamagnetism

In the original TV series that made me think about magnetic propulsion they go back into the origin of the 'big bang'
they start with neutrons
those then are broken into electrons (negative) and protons (positive) by beta-decay,
and those then forms molecules and all sorts of matter and things as we know it
and the magnetic fields generated by those elementary particles then form the stars and galaxies, the  universe as we know it
Seems to be the latest science take on the big bang origin.

Was new to me, those magnetic fields that then form and hold stars and galaxies together are extremely strong they say.
So pure quantum stuff..

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#895045

[Quotation fixed, see <https://www.netmeister.org/news/learn2quote.html>]

John Hasler wrote:
> Ian wrote:
>> Thomas 'PointedEars' Lahn writes:
>>> You also need a large _gradient_ of magnetic field.
>> What is that even supposed to mean?
> 
> https://en.wikipedia.org/wiki/Magnetic_moment#Force_on_a_moment

A link to a Wikipedia article is not a sufficient explanation, not even when
you are referring to a section of such an article.

Probably you are referring to

| F_{loop} = ∇(m⃗ ⋅ B⃗)

This is NOT the "gradient of magnetic field".  It is the gradient of _the
scalar product of some magnetic moment m⃗ and the magnetic flux density field B⃗.

The magnetic (flux density) field is a _vector_ field (magnetic field: H⃗ =
B⃗∕μ₀ + M⃗, where M⃗ is the magnetization).  The gradient is only (simply)
defined for *scalar* fields (and produces a vector field).

Moreover, the magnetic field lines are closed, which is what

  ∇ ⋅ B⃗ = 0

means; so it is NOT defined by a gradient field (unlike the electric field:
E⃗ = -∇Φ, where Φ is the electric potential field), but a _curl_ field: the
curl of the magnetic vector potential --

  B⃗ = ∇ × A⃗

(because the divergence of a curl field is zero), -- so it does not make
sense to speak of the gradient of the magnetic field.

At best, one can speak of the _directional_ gradient of _the strength_ of
the magnetic (flux density) field (which then is a scalar field); but then
you have to specify the direction, too.

For example, the magnetic field around an "infinitely long" cylindrical
conductor with radius R through which a uniform current I is flowing is in
SI units

  B⃗(r) = {(μ₀/2) (I r/R^2) e⃗ᵩ, 0 <= r < R;
          (μ₀/2) (I/r) e⃗ᵩ,     r >= R,

so

  B(r) = {(μ₀/2) (I r/R^2), 0 <= r < R;
          (μ₀/2) (I/r),     r >= R,

and

  ∇_r B(r) = ∂_r B(r) = {(μ₀/2) (I/R^2), 0 <= r < R;
                         (μ₀/2) (-I/r^2), r >= R.

This shows that in this case the only way to have the strength of the
magnetic field inside the conductor fall of faster than linearly is to have
an electric current density that decreases with the distance from the axis
of the conductor.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#895028

On Mon, 2 Feb 2026 05:40:10 +0100, Thomas 'PointedEars' Lahn
<PointedEars@web.de> wrote:

>Ian wrote:
>> Stefan Ram wrote:
>>> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>>> What are the effects of magnetic field lines on star formation in
>>>> galaxies?
>>>
>>>   These natural magnetic fields in galaxies and their gradients,
>>>   I think, are relatively weak. Over long timescales and over larger
>>>   spatial regions, their effects can accumulate and become noticeable.
>>>   But to drive a spacecraft, you'd need fields that are fairly strong
>>>   at the location of the ship and at the moment the ship is there.
>> 
>> You also need a large _gradient_ of magnetic field.
>
>What is that even supposed to mean?

It means that there is no perpetual motion, no free energy.


John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics

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#895029

john larkin <jl@glen--canyon.com> wrote or quoted:
>On Mon, 2 Feb 2026 05:40:10 +0100, Thomas 'PointedEars' Lahn
><PointedEars@web.de> wrote:
>>Ian wrote:
>>>Stefan Ram wrote:
>>>>Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>>>>What are the effects of magnetic field lines on star formation in
>>>>>galaxies?
>>>>These natural magnetic fields in galaxies and their gradients,
>>>>I think, are relatively weak. Over long timescales and over larger
>>>>spatial regions, their effects can accumulate and become noticeable.
>>>>But to drive a spacecraft, you'd need fields that are fairly strong
>>>>at the location of the ship and at the moment the ship is there.
>>>You also need a large _gradient_ of magnetic field.
>>What is that even supposed to mean?
>It means that there is no perpetual motion, no free energy.

  In rectangular coordinates, the gradient of a vector field 
  f =( f_1, f_2, f_3 ) is defined by:

"nabla" f 
= g^jk ("partial"f^i/"partial"x^j) e_i "tensor product" e_k,

  according to the section "Gradient of a vector field" 
  of the Wikipedia page "Gradient".

  So, when these derivatices ("partial"f^i/"partial"x^j) are
  large, the gradient is large, meaning the field changes a lot,
  which is need for a significant force on a magnetic dipole.

  Unicode:

𝙛=(𝑓¹,𝑓²,𝑓³)

∇𝙛=gⁱᵏ(∂fⁱ/∂xʲ) eᵢ⊗eₖ

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#895038

ram@zedat.fu-berlin.de (Stefan Ram) wrote or quoted:
>In rectangular coordinates, the gradient of a vector field 
>f =( f_1, f_2, f_3 ) is defined by:

  That should read, "f^1, f^2, f^3".

>"nabla" f 
>= g^jk ("partial"f^i/"partial"x^j) e_i "tensor product" e_k,

>So, when these derivatices ("partial"f^i/"partial"x^j) are

  "derivatives"

  "g_jk" are the components of the inverse metric tensor and the 
  "e_i" are the coordinate basis vectors. The Wikipedia page also
  has a definition that does not use a basis.

>large, the gradient is large, meaning the field changes a lot,
>which is need for a significant force on a magnetic dipole.

  "needed"

>𝙛=(𝑓¹,𝑓²,𝑓³)
>∇𝙛=gⁱᵏ(∂fⁱ/∂xʲ) eᵢ⊗eₖ

𝙛=(𝑓¹,𝑓²,𝑓³)

∇𝙛=𝑔ⁱᵏ(∂𝑓ⁱ/∂𝑥ʲ) eᵢ⊗eₖ

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#895042

john larkin wrote:
> [...] Thomas 'PointedEars' Lahn <PointedEars@web.de> wrote:
>> Ian wrote:
>>> Stefan Ram wrote:
>>>> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>>>> What are the effects of magnetic field lines on star formation in
>>>>> galaxies?
>>>>
>>>>   These natural magnetic fields in galaxies and their gradients,
>>>>   I think, are relatively weak. Over long timescales and over larger
>>>>   spatial regions, their effects can accumulate and become noticeable.
>>>>   But to drive a spacecraft, you'd need fields that are fairly strong
>>>>   at the location of the ship and at the moment the ship is there.
>>>
>>> You also need a large _gradient_ of magnetic field.
>>
>> What is that even supposed to mean?
> 
> It means that there is no perpetual motion, no free energy.

My question was what "_gradient_ of magnetic field" is supposed to mean
because the magnetic field is a _vector_ field, and the gradient is only
defined for *scalar* fields.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#895043

Thomas 'PointedEars' Lahn wrote:

> Ian wrote:
>> Stefan Ram wrote:
>>> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>>> What are the effects of magnetic field lines on star formation in
>>>> galaxies?
>>>
>>>   These natural magnetic fields in galaxies and their gradients,
>>>   I think, are relatively weak. Over long timescales and over larger
>>>   spatial regions, their effects can accumulate and become
>>>   noticeable. But to drive a spacecraft, you'd need fields that are
>>>   fairly strong at the location of the ship and at the moment the
>>>   ship is there.
>> 
>> You also need a large _gradient_ of magnetic field.
> 
> What is that even supposed to mean?

A magnet has a north and a south pole. In a uniform magnetic field,
there will be equal and opposite forces on these. To obtain a net
force, the magnetic field must be different at the N and S poles. That
is, the field must have a non-zero gradient. (Check dictionary, if
necessary)

[unintelligible crap elided.]

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#895044

Ian wrote:
> Thomas 'PointedEars' Lahn wrote:
>> Ian wrote:
>>> Stefan Ram wrote:
>>>> Jan Panteltje <alien@comet.invalid> wrote or quoted:
>>>>> What are the effects of magnetic field lines on star formation in
>>>>> galaxies?
>>>>
>>>>   These natural magnetic fields in galaxies and their gradients,
>>>>   I think, are relatively weak. Over long timescales and over larger
>>>>   spatial regions, their effects can accumulate and become
>>>>   noticeable. But to drive a spacecraft, you'd need fields that are
>>>>   fairly strong at the location of the ship and at the moment the
>>>>   ship is there.
>>>
>>> You also need a large _gradient_ of magnetic field.
>>
>> What is that even supposed to mean?
> 
> A magnet has a north and a south pole.

Not necessarily.  For example, Earth as a magnet has multiple magnetic
poles, but only two primary ones (where most magnetic field lines end):

<https://en.wikipedia.org/wiki/Earth%27s_magnetic_field>

> In a uniform magnetic field,

There is no such thing, or *only approximately*, as magnetic field lines are
*closed* lines ("an infinitely long cylindrical electromagnet has a uniform
magnetic field inside, and no magnetic field outside" [1], but in reality
there is no such thing as "an infinitely long cylindrical electromagnet").

One of Maxwell's equations (Gauss' Law for Magnetism) is in differential form

  ∇ ⋅ B = 0,

which is equivalent to the statement before; because if for any volume as
much "field" is "flowing out" as is "flowing in" (which is indicated by the
field lines, their density, and their direction, then the divergence of the
field is zero everywhere:

  ∰_V dV (∇ ⋅ B) = ∯_A dA ⋅ B = 0,

where in the first identity we have used Gauss' Theorem to describe the
problem in terms of the amount of "field" that is flowing out perpendicular
to surface that is enclosing the volume.

The simplest magnetic field, that of a bar magnet, therefore looks
approximately like this (use a fixed-width font to view it):

       _         _
    .'' ''.   .'' ''.
   :   .''.: :,''.   '
  :   :  .::-::.  :   :
  :   :  |::N::|  :   :
  :   :  |:: ::|  :   :
  :   :  |:: ::|  :   :
  :   :  |:: ::|  :   :
  v   v  |^^ ^^|  v   v B
  :   :  |:: ::|  :   :
  :   :  |:: ::|  :   :
  :   :  |:: ::|  :   :
  :   :  |::S::|  :   :
  :   :  '::-::'  :   :
   .   '--': :'--'   .   __
    '.._..'   '.._..'   |PE


Notice how these field lines are *closed* lines, and only *approximately*
parallel within any given volume.

[1]
<https://en.wikipedia.org/wiki/Magnetic_field#Interactions_with_electric_currents>

> there will be equal and opposite forces on these.

Nonsense.

> To obtain a net force, the magnetic field must be different at the N and S
> poles.

It *is* different (it has a different direction at each pole; see above),
but your conclusion is wrong.

> That is, the field must have a non-zero gradient. (Check dictionary, if
> necessary)

Nonsense.  The magnetic field is a *vector* field.  The gradient operator
for it is not (simply) defined, and the field does not do any work on a
charged particle.

> [unintelligible crap elided.]

ISTM that you want to troll more than you want to discuss and learn.


BTW, you are violating RFC 5536 and Netiquette (Network etiquette) by not
providing an actual e-mail address in the "Reply-To" header field value of
your postings (sfuu.cs is not a registered second-level domain):

<https://www.rfc-editor.org/rfc/rfc5536#section-3.2>
<https://www.rfc-editor.org/rfc/rfc5322#section-3.6.2>

Noticing this, maybe the character string in the "From" header field value
of your postings is not actually an e-mail address either, but an attempt at
trolling (perhaps expressing homophobia as well; CMIIW), in which case you
would be not only be violating RFC 5536 and Netiquette, but also the
namespace of Simon Fraser University in Canada:

<https://www.rfc-editor.org/rfc/rfc5536#section-3.1.2>
<https://www.sfu.ca/>

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail.

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#895083

ram@zedat.fu-berlin.de (Stefan Ram) wrote or quoted:
>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.

  There is a nice video 

"Animation vs. Physics" (2023) - Alan Becker

  where near minute seven, coils placed in space are used to accelerate
  a space ship. While this might not work in reality, it's still nice
  to watch that whole video from start to end (16 minutes).

  I just see there's another video "Animation vs. Math" I have not 
  watched yet . . .

  PS: A web page explains that the idea was that "the south pole of
  Orange's ship is facing the north pole of the first magnetic ring"
  and so the ship is accelerated towards the ring. However, the video
  ignores that when leaving the ring, the ship is still attracted to
  the ring, and therefore it would then be accelerated backwards . . .

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#895015

On 1/02/2026 10:57 pm, Jan Panteltje wrote:
> I was watching some stuff of magnetic field lines in the universe
> that I recoded last week from  zdfinfo.de
>   https://www.zdf.de/dokus/geheimnisvolles-universum-100
> It seems those are playing a much bigger role in the forming of galaxies and stars and the 'big bang' in the latest research.
> 
> 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
> could be used as a simple fuel-less drive?
> Electromagnets should work too of course.
> 
> Any aliens here that have used it?

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

-- 
Bill Sloman, Sydney

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#895016

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10lnl5f$3oefp$3@dont-email.me...
> On 1/02/2026 10:57 pm, Jan Panteltje wrote:
>> I was watching some stuff of magnetic field lines in the universe
>> that I recoded last week from  zdfinfo.de
>>   https://www.zdf.de/dokus/geheimnisvolles-universum-100
>> It seems those are playing a much bigger role in the forming of galaxies and stars and the 'big bang' in the latest research.
>>
>> 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
>> could be used as a simple fuel-less drive?
>> Electromagnets should work too of course.
>>
>> Any aliens here that have used it?
>
> 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
https://www.youtube.com/watch?v=-LrbTd69iwI

>
> -- 
> Bill Sloman, Sydney
> 

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#895032

Bill Sloman <bill.sloman@ieee.org> wrote:
> On 1/02/2026 10:57 pm, Jan Panteltje wrote:
> > I was watching some stuff of magnetic field lines in the universe
> > that I recoded last week from  zdfinfo.de
> >   https://www.zdf.de/dokus/geheimnisvolles-universum-100
> > It seems those are playing a much bigger role in the forming of galaxies and stars and the 'big bang' in the latest research.
> > 
> > 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
> > could be used as a simple fuel-less drive?
> > Electromagnets should work too of course.
> > 
> > Any aliens here that have used it?
> 
> Earth has a magnetic field, and nobody uses magnets to drag boats or 
> aircraft around.


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.

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