7 ms·
The magnetic universe begins to come into view
- deleted 6y ago[deleted]
- Andys 6y agoSeems alot more interesting than yet another failed searched for "dark matter"
- api 6y agoIf 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.
- torrance 6y agoThese fields can create forces, but they can't do work unfortunately.
- api 6y agoA magnetic field can't do work by interacting with another generated field? If so how do electric motors work? I must be missing something here.
- torrance 6y agoElectric fields do the work there. A charged particle in a magnetic field feels a force (Lorenz force) that act perpendicularly to its velocity. But work is only work if the force is applied in the direction of its velocity. Essentially it's changing its direction of momentum, but not its magnitude. On the other hand, some magnetic fields (not all) can be transformed into electric fields by a change of reference frame. In that case, the electric field can be used to do work. But I don't believe that's possible on these scales.
- dr_dshiv 6y agoI want to know things like this. Any recommendations for books or lectures?
- petermcneeley 6y agoViaScience has some very good lectures on physics. https://www.youtube.com/channel/UCx6G76LCKLdd7__F0xt5POQ https://www.youtube.com/channel/UCx6G76LCKLdd7__F0xt5POQ
- cli 6y agoAny undergraduate level textbook on E&M. Griffith's 'Introduction to Electrodynamics' is a commonly used one.
- avian 6y agoWay 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.
- whatshisface 6y ago>It would also only allow a one-way travel along the local field gradient. No round trips. Turn the magnet around?
- avz 6y agoAs 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.
- whatshisface 6y agoYou 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 6y agoReaction 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.
- rini17 6y agoFor similar reason you can't use Earth's magnetic field to lift stuff - it's so weak you need impractically strong magnet (note) and/or impractically big and at the same time lightweight structure. (note) and it must not be permanent magnet, as the sibling explains - you must vary the magnetic field to "convert it" into electric field which then does the lift
- im3w1l 6y agoMaybe if magnetism is combined with a gravitational slingshot it would be possible to extract energy.
- dghughes 6y agoElectrostatic would be a better choice. A great example I've seen is on the Hyperphysics website. It calculates two electrons with like charges of 1 Coulomb for 1 second repel each other with a million tons of force. edit: For magnetism I believe the force comes from virtual photons maybe electrostatic is on a different scale, either bigger or smaller.
- ecoled_ame 6y agomissions enabled by plasma magnet sails - https://youtu.be/0vVOtrAnIxM https://youtu.be/0vVOtrAnIxM everybody on 4chan /sci was talking about this a few weeks ago. seems like you can get incredible thrust from solar wind that increases proportionally with radius from the sun for constant acceleration, all with a small standard electric motor. upon cursory investigation by me it seems sorta legit. needs testing beyond earth orbit but ground tests are reported to be successful.
- whoopdedo 6y agoBit 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/@52.9147159,6.8687104,1358m/data=!3m2!1e3!4b1 https://www.google.com/maps/place/LOFAR+superterp/@52.914715... [2] https://www.google.com/maps/place/National+park+Dwingelderveld/@52.8071007,6.3909835,2561m/data=!3m1!1e3 https://www.google.com/maps/place/National+park+Dwingelderve...
- consp 6y agoLooks like it was placed in a normal agricultural field in the Netherlands. It is mostly long patches with "moats" at the sides (irrigation) like all the other ones around that location. And they made sure cows could not get on it by making it surrounded by a bigger patch of water as the observational stuff is placed in a circle, I guess. But this is a non-educated opinion based on observation only.
- pp19dd 6y agoNot 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=52.91525,6.86982,10.974,latLng&t=1.1&ps=100&bt=19840101&et=20181231&startDwell=0&endDwell=0 https://earthengine.google.com/timelapse#v=52.91525,6.86982,...
- twic 6y agoThere are many strange and wonderful circles to be seen in the Netherlands. For example, the IJsseloog: https://www.google.com/maps/place/IJsseloog/@52.5969321,5.7365816,2817m/data=!3m1!1e3 https://www.google.com/maps/place/IJsseloog/@52.5969321,5.73...
- kwoff 6y agoIt's very common to see these water ditches in the Netherlands, since 1/3 of the country is below sea level. Land rescued from water is called a polder: https://en.wikipedia.org/wiki/Polder https://en.wikipedia.org/wiki/Polder
- Stierlitz 6y ago“These force fields — the same entities that emanate from fridge magnets” Not a lot of people know that :]
- pantulis 6y agoWell, not a lot of people understand magnetism anyway.
- empath75 6y agoIf this explains expansion, then it also eliminates dark energy, no?
- andrewflnr 6y agoIf 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.
- cabite 6y agohttps://www.youtube.com/watch?v=1A6ikRgZBf8 https://www.youtube.com/watch?v=1A6ikRgZBf8
- saas_sam 6y agoThis 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.
- gliese1337 6y agoThe Electric Universe is a much different, much more wide-reaching bit of crackpottery than this.
- cthalupa 6y ago>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.
- peter_d_sherman 6y ago>"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."
- abrichr 6y agoThe "cosmic web" rendering (https://www.quantamagazine.org/the-hidden-magnetic-universe-begins-to-come-into-view-20200702/ https://www.quantamagazine.org/the-hidden-magnetic-universe-...) reminds me of neurons (https://static.scientificamerican.com/sciam/cache/file/52B19135-A87E-4900-8787C55A19925989_source.jpg?w=590&h=800&4482D8A9-1F12-45E6-8466C64DBDD4C9C3 https://static.scientificamerican.com/sciam/cache/file/52B19...) Is it possible that the universe is some sort of neural computation device? What could it be modelling?