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I'm designing a world that has a series of layered floating islands, that are kept aloft due to magnetism.

What sort of secondary effects might occur with a planetary magnetic field strong enough to keep these islands afloat and orbiting? For example, would strong fields have direct biological, technological, or climatic effects? Or would poles be affected in a special way?

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  • $\begingroup$ Welcome to Worldbuilding, El Nitromante! If you have a moment, please take the tour and visit the help center to learn more about the site. You may also find Worldbuilding Meta and The Sandbox (both of which require 5 rep to post on) useful. Here is a meta post on the culture and style of Worldbuilding.SE, just to help you understand our scope and methods, and how we do things here. Have fun! $\endgroup$ – Gryphon Jul 27 '18 at 14:05
  • $\begingroup$ Why are you using science based when you state there is light magic? $\endgroup$ – L.Dutch - Reinstate Monica Jul 27 '18 at 14:47
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    $\begingroup$ The world has some light magic elements, but the buoyancy of the islands itself is only magnetism-based (for now). I stated the light magic element to make clear I'm open to less scientific solutions to this problem. $\endgroup$ – El Nitromante Jul 27 '18 at 14:51
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    $\begingroup$ Welcome to the site. Please note that question posts with multiple questions are frequently closed as being too broad. (And has already placed this question in the review queue.) After looking over the question a few times, I disagree with the close vote. This is asking one distinct question: What impact on life/technology would an extremely strong magnetic field have? $\endgroup$ – Frostfyre Jul 27 '18 at 16:06
  • $\begingroup$ See solomon.as.utexas.edu/magnetar.html "Fields in excess of 109 Gauss, however, would be instantly lethal. Such fields strongly distort atoms, compressing atomic electron clouds into cigar shapes, with the long axis aligned with the field, thus rendering the chemistry of life impossible." I don't know how much magnetism is required to make a continent float, but it's a lot. $\endgroup$ – RonJohn Jul 30 '18 at 1:52
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First things first: the planet's magnetic field will not help you. A typical value for the Earth's geomagnetic field on the surface is ~30 microteslas, whereas a standard kitchen magnet is in the neighborhood of 5 milliteslas (= 5000 microteslas), or about 165x as strong. And kitchen magnets are not going to keep an island in the sky very long. In all probability you'd have to change the composition of the planet so much that it wouldn't really be Earthlike any more.

You could posit that the crust of your planet contains permanent magnets and/or superconducting magnetic material in abundance, which repulses bits of crust that are the wrong polarity: hence the sky islands. (This is how the unobtainium works in Avatar and Civilization: Beyond Earth; I'm sure there are others.) Technically speaking this probably wouldn't actually work, but it's near enough for fiction.

Permanent magnets in the crust in particular should pose less danger to computers and electronics in general. To oversimplify, electromagnetic theory says that changing electric fields cause magnetic fields, and moving magnetic fields cause electric fields. As long as they remain relatively stable, the effects should be minimal. If one of your islands starts moving around, or worse, crashes, that could cause a major electromagnetic incident.

As far as I'm aware, these sorts of magnetic field strengths wouldn't be directly harmful to life, and they wouldn't have an effect on most weather. (Having a giant, presumably ungrounded bundle of matter floating in midair might do something odd to thunderstorms, though.)

According to this paper, you can actually levitate live animals with a field strength of about 16 teslas, and it's perfectly safe.

Of course this represents the summation of microscopic currents localized in atoms, not the bulk transport of charge, so the living creatures were not electrocuted. Indeed, they emerged from their ordeal in the solenoid without suffering any noticeable biological effects—see also Schenck (1992) and Kanal (1996).

This is using a strong solenoid magnet on the one hand, and the fairly weak induced magnetism of the water in the frog's tissue on the other hand. It suggests that biology won't be a major source of problems.

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Unless you want spinning islands or a very fast-changing magnetic field, you probably want diamagnetically floating islands.

So, the islands contain large amounts of highly diamagnetic materials. There is a reasonable overlap between diamagnetic materials and superconductive materials. So, your society could have easy access to room-temperature superconductive materials!

This would have a lot of useful applications - your computers (the fact you can now have a static magnetic field means there will be relatively little effect on electronics) could soon be far superior to our own.

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  • $\begingroup$ That surely opens some interesting new possibilities, but I actually hoped to be able to keep the strong magnetic field idea in order to avoid the development of computers and most advanced electrical technology so I could keep the world running on mechanics for the most part. Although I had also planned some sort of sentient android built from ceramics and such so the field wouldn't tear it apart. $\endgroup$ – El Nitromante Jul 27 '18 at 17:13
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Electromagnetic energy, as far as I know, has very little effect on living things. DNA and such would be safe on this world - probably more so than on earth, as high-intensity cosmic rays would be greatly deflected.

Computers would be difficult - geomagnetic storms here on earth can already cause problems. Radio communication is unlikely. Electric lights could be possible (in fact, you might be able to use antennae to power them - geoelectric power!), and perhaps some limited computers with vacuum tubes (generally more resistant to geomagnetic effects).

I'm not sure how to calculate the stability of a magnetic field of that size.

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