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From: throopw@sheol.UUCP (Wayne Throop)
Newsgroups: sci.physics,sci.bio
Subject: Re: Magnetic Levitation of Organic Materials
Summary: just how big is "enormous"?
Message-ID: <1689@sheol.UUCP>
Date: 15 Apr 91 03:24:59 GMT
References: <1489@gtx.com> <40065@fmsrl7.UUCP>
Lines: 23

> wreck@fmsrl7.UUCP (Ron Carter)
>> al@gtx.UUCP () 
>> [..could..] a person's body could be levitated [..by a magnetic field..]
>> Would the great field strength or gradient thereof have any significant
>> effect on, say, electrical activity in nervous tissue [...]
> Hell, yes.  [...] introduce an enormous magnetic field.  Every moving
> ion will experience a BxV force, and every blood vessel which is
> not parallel to the ambient field becomes an MHD generator [...]
> [...] It sounds dangerous.

Well, I don't know how enormous you folks mean by "enormous".  But
unless I'm much mistaken in my memory of reading the resulting images,
MRI (the euphemism for what used to be called NMR imaging) involves
subjecting a person to magnetic fields of between 1 and 2 trillion (as
in 10^12) gauss.  The person I saw in the device didn't levitate.  Nor
fry, nor heart-fail, nor nothing. 

If I'm mistaken about the field strength involved in MRI, I'd appreciate
being corrected.  As I said, I remember being somewhat amazed at a
reading of 1.mumble terragauss on the statistics printed on the image
output.
--
Wayne Throop  ...!mcnc!dg-rtp!sheol!throopw