I am writing a fantasy/sci-fi where humans crash-land on a somewhat earthlike planet (continental distribution, great masses of water, similar element's abundance), however, I would like for one of the planet's "perks" to be that ferromagnetic metals would weight less.
Please notice I am not talking about general gravity, as other materials would be close to a 1:1 weight in comparison to Earth's gravitational pull (maybe I can sacrifice 10 - 15% gravitational pull and make it 0.85:1 if that helps, I'd prefer to avoid it nevertheless, as I'd have human bone structure and overall muscle composition to remain the same in time). We are talking about a magnetic field "push" capable of halving gravitational "pull" for certain materials sensible to the former.
I've read through many similar questions and answers on the site, but almost all of them are asking for stronger "pulling" field effects and applications, which is exactly the opposite of what I want.
Assumptions are the following:
- 1kg of Ferromagnetic material would weight half of that.
- Planetary diameter is similar to that of the earth. Rotational speed can be +/- 20%.
- The "source" of the "reversed" magnetic field is at the core of the planet. It's origin, nature or composition are not important.
- Despite being crash-landed, therefore spacefaring tech, society (the survivors) would have devolved into late middle-ages / renaissance tech levels, with some boosts regarding engineering due to "light" metals. So... no electronics.
- Given the strength of the field, a fine ferromagnetic dust (or cloud) would hover over certain parts of the planet's atmosphere. And Ferromagnetic material deposits would be really near to the surface of the planet.
- How strong should this magnetic "push" have to be?
If other "factors" of the "similar to earth" equation can be tweaked in order to make it more plausible, feel free to make a suggestion.
All of this can be "handwaved" and just left to suspension of disbelief, but I'd like to base it at least on "some" actual science and know how far can I pull (or push) it's limits.
I am sorry if I make some mistakes with terminology and/or units, my physics knowledge peaked at high-school. Thank you very much for your time and I would greatly appreciate any help.
Answers to Comments:
Iron is a ferromagnetic material. Objects made of ferromagnetic materials are always attracted by magnets; one cannot make an "anti-magnet" which would repel ferromagnetic objects (...)
Thank you for the clarification, it got me thinking. Given that this is sci-fi (and the words "one cannot make" don't fully apply) didn't you just come up with an interesting candidate for an idea? an "anti-magnet"... I would like to explore that further.
(...) what is the intended effect on your story or plot of ferrous metal being "lighter"? If you can explain that, we may be able to find a more plausible way to accomplish it.
Sure. Basically I want a world/universe without magic (understanding magic as "fantasy" magic i.e. "fire, arcane, ice, healing" and so on, and not as very advanced technology which could be perceived as magic by less advanced cultures), therefore I thought of magnetism as one possible candidate for a force that could bring me the desired results.
Plot-wise, civilization is composed of the descendants of a settlement ship that crash-landed a couple thousand years in the past. Little cities have emerged using the scraps from the hunks of the huge ship. As Iron is naturally abundant (and a "light" material for them), people would use it a lot in combination with "ship-metals" and build with it. The thing is, this anomaly is caused by "something" in the center of the planet, and somewhere along the story, by agency of someone, it stops, and every "light" metal suddenly weights 2 or 3 times more.
I guess, if it is too much to handle "naturally", I can do with the "something" being some artifact/building of unknown origin, I guess everything is possible with alien tech.