From: g_d_pusch_remove_underscores@xnet.com   
   Copy: zoltanccc@aol.com   
      
   zoltanccc@aol.com (Zoltan Szakaly) writes:   
      
   > I have recently found out that a hamster was levitated by applying a   
   > strong magnetic field of 16 Teslas using a superconducting   
   > electromagnet.   
   >   
   > This is significant to me because you could use the technology to   
   > potentially create artificial gravity on spacecraft.   
      
   This idea has been discussed many, many times before in this newsgroup.   
   The effect depends on the field _gradient_. Given the current material   
   limitations on superconductor  critical field strengths, it is not practical   
   for objects much larger than frogs or hamsters. Furthermore, the amount of   
   energy that would be stored in such a field is impractically large, and the   
   magnetic field would play all sorts of hob with electronics and other   
   instruments.   
      
   _Do_ please try to do some background research and to run some numbers   
   on your "ideas" before posting them; you will stick you foot in your mouth   
   less often.   
      
      
   > You could also use it compensate for the effects of acceleration. For   
   > example a car hitting a wall, could be equipped with a magnetic airbag   
   > that decelerates the people without harm to the internal organs.   
      
   Again, it is not practical for object as large as a human being, even in a   
   one-gee field, let alone the peak of tens to hundreds of gees experienced   
   in an automobile collision. Furthermore, even if sufficiently strong field   
   gradients _could_ be produced, the amount of stored energy in the field   
   would be impractically large. Still further, the inductance of the field   
   coils will be so large that it is utterly impractical to energize them   
   with a fast enough rise-time to offset the rate of onset of the collision.   
      
   Finally, since the force is primarily exerted on soft tissues with varying   
   water contents, while bones are massive and do not contain significant   
   quantities of water compared to soft tissues, the differential accelerations   
   sustained by the various parts of the body will still kill you.   
      
      
   > You could create a bed that levitates you and so it is more   
   > confortable than the usual foam stuff.   
      
   If you could afford the unobtainium superconductors, and didn't mind the fact   
   that your "bed" will grab every ferrous object in its immediate neighborhood   
   and accelerate them toward itself at dangerously large rates...   
      
      
   > You could create an astronaut training facility with magnetic   
   > levitation.   
      
   Except that you can't make a strong enough magnetic field with a large   
   enough field gradient over a big enough volume --- and even if you could,   
   since magnetism does not affect every part of the body equally, your   
   astronaut trainees would experience strong differential forces on different   
   parts of their bodies, which would utterly ruin the illusion of zero-gee.   
      
      
   > You could make vehicles that hover over the Moons surface and not stir   
   > up dust as they move about.   
      
   No you can't: The Moon's surface is not diamagnetic.   
      
      
   > The applications are endless if you can figure out how to keep your   
   > superconductors cold.   
      
   And if pigs had wings they might fly, and if you had some bacon, you might   
   make some bacon and eggs, if you had some eggs, and if wishes were horses,   
   even beggars would ride...   
      
      
   -- Gordon D. Pusch   
      
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