In my previous question (Could magnetism work in place of gravity for large bases in space?), @JBH brought up that ferrofluids in the diet of people on these stations could keep them magnetically attracted to the station’s floor, keeping their biological functions stable, similar to gravity. But is that feasible? Mass added by ferrofluids could cause serious biological problems, and magnetism weakens a lot faster with increase in distance between the two objects. Any ideas on how ferrofluids could solve the problem, or how to solve the new problems it creates?

Edit: Never mind, ferrofluids would definitely not work in this case.

  • $\begingroup$ possibly relevant Wikipedia page magnetotactic bacteria $\endgroup$
    – Topcode
    Commented Nov 14, 2022 at 19:29
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    $\begingroup$ Apart from the likely fatal results of replacing a significant portion of bodily fluids with ferrofluids, watch some YouTube videos about what ferrofluids actually do in magnetic fields. Now imagine your blood trying to do that when you turn the "gravity" on. $\endgroup$ Commented Nov 14, 2022 at 21:42
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    $\begingroup$ What is wrong with centrifuges, again? $\endgroup$ Commented Nov 15, 2022 at 18:02
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    $\begingroup$ @Jobah_HigherMind for tours of duty of less than a year, microgravity is fine. Compact centrifuges for sleeping in are also a possibility. $\endgroup$ Commented Nov 15, 2022 at 18:38
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    $\begingroup$ what an elaborate way to go about murdering your crew. Surely opening the airlocks would be both more humane and cost-efficient. Also, apart from the only heavily downvoted answer that also happen to be the one you accepted, all answers to your previous question already pointed out that the very idea of replacing gravity with magnetism is... not a great one $\endgroup$ Commented Nov 19, 2022 at 11:25

2 Answers 2


Using ferrofluids to make magnetic gravity possible is literally the worst idea ever

First of all, ferrofluid simply doesn't behave like a fluid that sticks to iron. Have you seen what ferrofluid does in the presence of a magnetic field. It forms spike-like structure like the one in the image belowenter image description here

Unless you are a chad-transhumanist species that has adapted to all kinds of inhospitabilities in space, then, I wouldn't like to have my arteries bulging out in spikes whenever "gravity" is turned on.

Even if you forgot blood and went ahead with putting ferrofluids in the flesh, organs and all other parts of the body, you run into the serious problem: Magnetism increases dramatically as you get closer to the magnetic source.

Gravity decreases gradually the further you go away from the mass that is generating gravity. Gravity decreases with the inverse square of distance, or that the gravitational force is proportional to $1/r^2$, whereas magnetism on the other hand decrease with the inverse cube of distance, or that it is proportional to $1/r^3$

Do this activity: Take a magnet, and gradually bring a iron nail closer to it slowly. At a certain point, you suddenly feel a tug on the nail. The magnet is pulling much harder on the closer side of the nail, than on the further side.

Gravity is basically the only force that doesn't dramatically increase the closer you get to the source. That's the opposite with magnetism. The closer you get to it, it increases dramatically. If you had ferrofluids in your body, the "gravity" would pull on the side of the body closer to the magnet, i.e. the foot, more than it does on the further side of the body, i.e. the head. This can tear you apart.

Furthermore, ferrofluids are nothing more than a bunch of iron particles being dissolved in a solvent, most commonly vegetable oil, as vegetable oil doesn't react with iron and rust it. This means that, you are replacing a significant fraction of your body fluids with a immiscible fluid. Furthermore, these iron particles can cause a series of clotting and other terrible stuff to your body once introduced into the body.

TLDR: Use ferrofluids, body starts to spike out and burst, or else blood vessels would clot.

I will always stick to centrifuges and O'Neill cylinders. At least you don't run the risk of feet bursting due to ferrofluid spiking, or blood clotting due to iron particles.

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    $\begingroup$ Yeah, using ferrofluids was a bad idea. I thought it was attracted to magnetic poles, but I was wrong. $\endgroup$ Commented Nov 18, 2022 at 15:54
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    $\begingroup$ +1 for "chad-transhumanist" species $\endgroup$
    – Daron
    Commented Nov 18, 2022 at 17:20
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    $\begingroup$ "I wouldn't like to have my arteries bulging out in spikes whenever "gravity" is turned on." You big baby. $\endgroup$
    – DKNguyen
    Commented Nov 18, 2022 at 22:53

Could ferrofluids give humans magnetic properties?


The ferrofluids would have to be adequately distributed so that individual particles aren't too close to each other, but that's what you'd expect to need anyway (rather than a single large blob of pure ferrofluid).

For more fun; humans already have some (exteremely weak) natural magnetism due to iron in their blood, but it tends to cancel. Specifically; oxygenated hemoglobin is repelled by magnets and un-oxygenated hemoglobin is attracted by magnets.

In other words, I'd say it's plausible (in futuristic science fiction) for scientists to have found a way to improve the natural magnetism (via. some form of very diluted ferrofluids).

The real problem is whether or not this would fix the supposed "serious biological problems". For things like loss of balance it'd depend where the ferrofluids are (injected into inner ear, or in blood stream). For other things you'd have to start by determining what the biological problems are.


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