MadSci Network: Physics

Re: Is it possible to create gravity in space with an electro magnet?

Date: Fri Apr 1 09:28:51 2005
Posted By: Anthony Klon, Staff, Molecular Modeling, Pharmacopeia, Inc.
Area of science: Physics
ID: 1112093814.Ph

Dear Remo,

Your question, as I understand it, seems to contain two parts: 1) Is it 
possible to generate such a field with a living organism (like a human 
being), and 2) Could this be used to approximate the effects of gravity in 
a zero g environment.

To answer the first part, a number rather unusual items have been 
levitated using the method you mention (or one similar to it), including 
live frogs and grasshoppers in magnetic fields with a strength of ~10 
Tesla at the High Field Magnetic Laboratory at the University of Nijmegen:

Fortunately, there are no known adverse health effects associated with 
living tissue in the presence of strong electromagnetic fields. To give 
you an idea, most MRI machines in use in U.S. hospitals operate at between 
0 – 2.0 Tesla (5000 – 20000 Gauss), although there are examples of 4 Tesla 
machines, and an 8 Tesla machine was recently unveiled at the Ohio State 
University in Columbus. Compared to the Earth’s magnetic field, which has 
a field strength of only 0.5 Gauss, these magnets are quite powerful.

This levitation occurs because all materials, including living organisms 
are diamagnetic. (Paramagnetism, the mild attraction to a magnetic field, 
is stronger in objects with unpaired electrons.) The electrons present in 
the diamagnetic object align themselves anti parallel relative to the 
external magnetic field, creating an induced magnetic field. In the case 
of our frog (or your strawberry), the electrons in every molecule of its 
body are aligned by the external magnetic field. This results in the 
levitating body exerting a very small force opposite in direction to the 
external magnetic field, resulting in a force about 1e-5 times the 
strength of this external field and opposite in direction.

So, it is possible to generate such a force in a living organism and it 
would likely not have any adverse health effects. However, there are a 
couple of snags which would seem to preclude its use in a spaceship. The 
first is that the presence of such strong powerful magnetic fields 
throughout a spaceship will likely wreak havoc with all of a ship’s 
electrical systems. Not to mention the fact that metallic objects would 
likely have to be removed. (Click on the link below to see the effects of 
a fully loaded pallet jack sucked into the bore of an MRI.)

Another potential problem lies in the generation of the fields themselves. 
As discussed by Berry and Geim (Berry MV and Geim AK, “Of flying frogs and 
levitrons” Eur. J. Phys. 18 (1997) 307-313), the fields used to levitate 
diamagnetic objects operates by creating regions of equilibrium where the 
forces of gravity and the induced magnetic field cancel each other out. As 
the authors describe, there is a shape-induced dependency of the induced 
magnetic moment, and levitation occurs at a point which is an energy 
minimum inside the solenoid possessesing spherical symmetry. This suggests 
that if such a field were used to ‘suspend’ an individual on the floor of 
the spaceship, walking around would cause one to leave the field, thus 
leaving the energy minimum. So, a person on the spaceship would only 
experience this ‘artificial gravity’ at a single point.



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