1
$\begingroup$

If you create a electromagnetic field under a surface could you then create artificial gravity effect by wearing magnetized clothing and shoes?

Or could you bombard objects that you want to experience gravitational forces with artificial gravitons or graviolis? Or inject or drink a ferrofluid (non-toxic) like that used in rocket fuel?

A ferrofluid (portmanteau of ferromagnetic and fluid) is a liquid that becomes strongly magnetized in the presence of a magnetic field. A grinding process for ferrofluid was invented in 1963 by NASA's Steve Papell as a liquid rocket fuel that could be drawn toward a pump inlet in a weightless environment by applying a magnetic field.

https://en.wikipedia.org/wiki/Ferrofluid

What I mean is create the forces of attraction and then make the objects you want to attract attractive, obviously.

This is as opposed to using other methods such as acceleration or centrifugal or centripetal force (or in addition to it).

$\endgroup$
5
$\begingroup$

There are two aspects to this question: first, creating a field that can exert a force and second, having a body that is coupled to that field and "feels" the acceleration.

Electric field: You probably want a uniform field of acceleration, like on earth, where the same amount of gravity is present everywhere in our daily life (close to the surface of earth). This can be achieved by putting sources into floor and ceiling of your ... space station. With various setups this could create a homogeneous electric field (like a parallel plate capacitor).

Now, use the field by putting charged bodies into it. I could imagine a space suit with an eletrically charged layer, insulated on both sides. I don't have an idea for a suit in the magnetic field though, because there are no magnetic charges.

Quick calculation: Assume a spherical human with a radius $r$ of half a meter. The suit is a charged conducting sphere and charging it with $V_\text{suit}=1\mathrm{MV}$, which is a lot, even for Marx generators, then the charge stored in the suit is

$$Q = V_\text{suit} 4\pi \epsilon_0 r = 6\cdot10^{-5}\,\mathrm{C}\,.$$

This doesn't look like a lot in the exponent, but Coulomb is an insanely large unit. Now charging up the capacitor formed by floor and ceiling to some voltage $V_\text{deck}$, the total force on the suit is

$$F = E \cdot Q = \frac{V_\text{deck}}{d}\, Q$$

And the acceleration of the body should be one g:

$$F = m a = m g$$

At a mass of lets say $m=70\,\mathrm{kg}$ this requires a voltage of:

$$V_\text{deck} = \frac{m g d}{Q} = 2\cdot10^7\,\mathrm{V}$$

Good luck with that :-) The typical dielectric strength of air is $3\mathrm{MV}/\mathrm{m}$ so you would instantly get an electrical arc between floor and ceiling.

Magnetic field: Magnetic fields behave a bit differently and the best option is probably a linearly varying magnetic field $\mathbf{B}$ from floor to ceiling (use Helmholtz coils). If you manage to build a suit with some magnetic dipole moment $\mathbf{m}$ (for example using a permanent magnet, or running a current through the suit), the force is

$$\mathbf{F} = \nabla (\mathbf{m} \cdot \mathbf{B})$$

The dipole moment of a normal neodymium magnet is given to be about $1\,\mathrm{Am}^2$ here. For the same $m=70\,\mathrm{kg}$ body the magnetic field has to have a gradient of 7 Tesla per centimeter ... or a difference of whopping 1400 Tesla from floor to ceiling (give or take one magnitude for not scaling the magnet to human weight). As a comparison, the magnets at LHC generate fields of about 10 Tesla.

Bottom line: Earth is big, therefore gravity at earth's surface is strong, because of that it's hard to reproduce it using electric or magnetic fields.

Graviton: The graviton is still a hypothetical particle. Even if we confirm its existence, its behaviour should be (for the large part) very similar to gravity as we know it. "Bombarding" something with gravitons is then equivalent to having a large mass nearby. Understanding the theory will most probably not enable us to build graviton guns that work analogous to lamps producing photons. Speaking of large masses, how about lining the floor with neutron star matter?

Ferrofluid: A paramagnetic material can be used to couple to the magnetic field, but I believe you need active stabilisation (circuits in the floor and ceiling). There actually seems to be a theorem about that: Earnshaw's theorem. There are other implications to drinking ferrofluids, besides the chemical toxicity, because it might accumulate in some spots of your body and more of the artificial gravity will attack at that spot.

I guess, we are still better off with gravity-like acceleration by rotation or propulsion ...

$\endgroup$
  • $\begingroup$ Good answer, and an honorary +1 for "assume a spherical human" $\endgroup$ – Asher Mar 20 '18 at 13:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.