
The magnetic universe begins to come into view - ernesto95
https://www.quantamagazine.org/the-hidden-magnetic-universe-begins-to-come-into-view-20200702/
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api
If magnetism pervades space, can interaction with these fields generate force
for propulsion? These fields are weak but what about extremely powerful
superconducting magnets? Even if the force is small it could add up over long
periods, and since no mass is needed it would be a "massless" drive that does
not violate any physical laws.

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avian
Way back in another life I did some calculations similar to that.

I don't remember details anymore, but there were some observations that some
(deep space) astronomical object somewhere was accelerating and there were no
models at the time that would explain that. I tried to explain it by a
magnetic dipole in an non-homogeneous interstellar magnetic field.

If you know the gradients and the dipole moment you can calculate the force on
the dipole.

I think it required a magnetar-level dipole to get some non-trivial forces out
of the interstellar field. Anyway, I don't know if that theory ever got
anywhere. Probably not. I never got any calls back from the people I presented
that work to.

A spaceship would have a much lower mass than a star or whatever I was
calculating that for, so I guess the requirements would be lower. Still, my
gut feeling would be a magnet much beyond what you can do with today's
superconductors. It would also only allow a one-way travel along the local
field gradient. No round trips.

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whatshisface
> _It would also only allow a one-way travel along the local field gradient.
> No round trips._

Turn the magnet around?

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avz
As with the compass, the orientation of your magnetic dipole against the field
is unstable, so now you need a second propulsion system for maintaining the
unstable orientation of the dipole.

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whatshisface
You don't need a second propulsion system, you could use reaction wheels[0].

[0]
[https://en.wikipedia.org/wiki/Reaction_wheel](https://en.wikipedia.org/wiki/Reaction_wheel)

~~~
avz
Reaction wheels saturate and are therefore more suited for precise attitude
control than as a source of sustained torque. Once they saturate you need to
unload the accumulated momentum via some other mechanism. Thus, you do need a
second propulsion system such as thrusters, light sail etc.

~~~
whatshisface
You can take the momentum back out of the wheels by rolling the magnet to the
other side of the unstable equilibrium so that the wheels have to accelerate
in the opposite direction to keep it steady.

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whoopdedo
Bit of a tangent, but I was curious about the circle lake in that picture of
LOFAR[1]. That can't be naturally occurring can it? It looks like a moat, and
I see lots of irrigation channels nearby. But maybe it was carved by a
glacier. There's another LOFAR location[2] next to a park that has a lot of
glacial lakes in it.

[1]
[https://www.google.com/maps/place/LOFAR+superterp/@52.914715...](https://www.google.com/maps/place/LOFAR+superterp/@52.9147159,6.8687104,1358m/data=!3m2!1e3!4b1)

[2]
[https://www.google.com/maps/place/National+park+Dwingelderve...](https://www.google.com/maps/place/National+park+Dwingelderveld/@52.8071007,6.3909835,2561m/data=!3m1!1e3)

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pp19dd
Not naturally occurring. Was shaped sometime between 2006 and 2007, give or
take a year. The interface is a bit jerky.

Hit play button at the very bottom:
[https://earthengine.google.com/timelapse#v=52.91525,6.86982,...](https://earthengine.google.com/timelapse#v=52.91525,6.86982,10.974,latLng&t=1.1&ps=100&bt=19840101&et=20181231&startDwell=0&endDwell=0)

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peter_d_sherman
>"One method, pioneered by the English scientist Michael Faraday back in 1845,

 _detects a magnetic field from the way it rotates the polarization direction
of light passing through it_.

The amount of “Faraday rotation” depends on the strength of the magnetic field
and the frequency of the light. So by measuring the polarization at different
frequencies, you can infer the strength of magnetism along the line of sight.
“If you do it from different places you can make a 3D map,” said Enßlin."

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abrichr
The "cosmic web" rendering ([https://www.quantamagazine.org/the-hidden-
magnetic-universe-...](https://www.quantamagazine.org/the-hidden-magnetic-
universe-begins-to-come-into-view-20200702/)) reminds me of neurons
([https://static.scientificamerican.com/sciam/cache/file/52B19...](https://static.scientificamerican.com/sciam/cache/file/52B19135-A87E-4900-8787C55A19925989_source.jpg?w=590&h=800&4482D8A9-1F12-45E6-8466C64DBDD4C9C3))

Is it possible that the universe is some sort of neural computation device?
What could it be modelling?

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jdmichal
I'm sorry, but I have to do it...

Clearly it's calculating the ultimate question to the ultimate answer to life,
the universe, and everything.

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saas_sam
This has been a popular fringe scientific theory for many years under the
title Electric Universe Theory. Fringe for sure, but its lead proponents tend
to be real scientists referencing real, peer-reviewed literature.

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cthalupa
>This has been a popular fringe scientific theory for many years under the
title Electric Universe Theory.

They're not at all related.

>but its lead proponents tend to be real scientists referencing real, peer-
reviewed literature.

They have real PhDs, some of them from respectable universities, but it's an
incestuous group that has people not participate in studies so they can all
peer review each other in "journals" with no real standing.

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empath75
If this explains expansion, then it also eliminates dark energy, no?

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andrewflnr
If I read it correctly, it only eliminates the conflict between a couple
different ways to measure the rate of expansion in the early universe. Dark
energy is about the rate accelerating over time, which is a different thing. I
do wish they had addressed it explicitly.

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Stierlitz
“These force fields — the same entities that emanate from fridge magnets”

Not a lot of people know that :]

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pantulis
Well, not a lot of people understand magnetism anyway.

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Andys
Seems alot more interesting than yet another failed searched for "dark matter"

