sci.physics.electromag

On Mar 1, 12:26 pm, Uncle Al wrote:
>
> http://www.mazepath.com/uncleal/lilies.htm
> http://www.mazepath.com/uncleal/field.htm

So I'm reading Unc's stories about "brain-sucking" NMR magnets and
that brought to mind some previous musings of mine.

Most of you here are into physical sciences but if for some reason you
would go to medical school, one of the classes you'd take would be
physiology and one of the experiments you'd do would be to cut open
some dogs and play with their hearts.

What you'd discover is that with voltages in the millivolt level a
wire touched to the outside of a beating heart (depending on the
electrical signal) can send it in to sudden arrhythmia (Known as
fibrillation...so called because it was originally believed that each
heart fiber was beating independently) or with a quick DC pulse send
it back into normal rhythm. Remember I said millivolts!

Now as you probably know from TV when the heart goes into such
arrhythmia emergency people use a device called a "defibrillator" It
is essentially a huge capacitor with a couple paddle electrodes
designed to send JOULES of energy through a patient's chest. Now the
reason for all this voltage and energy is that the heart is more or
less isolated from the rest of the body and is electrically isolated
even more by being covered with the pericardium sack. So much energy
and voltage is needed to defibrillate the heart that the machine often
burns the patient's tissue.

Well, crap, I've thought from time to time, I've seen with my own eyes
that all you need is MILLIVOLTS to do the job, so why in hell can't
one simply use a pulsed magnetic field as a defibrillator? One
additional piece of data came to me when I had an MRI scan. I thought,
hey, there is a really nice intense field there pulsing away, that
should surely induce some hum or noise in the nerves in my head or
ears! If it did, that surely would be evidence that one could build
an inductive defibrillator! Well, no soap. Lots of noise alright,
but as Uncle Al notes it was from the vibrations of the heavy current
coils and not my insensitive brain!

So how about it? Why won't a pulsed magnetic field induce nervous
firings? Why won't a pulsed magnetic field make your hand twitch? I've
heard that the Gummint has secret devices that can create voices in a
persons head (probably lots of victims here on usenet!) but that they
use microwaves rather than magnetic fields to do the job.

So why is it that one cannot build a magnetic defibrillator? Why won't
pulsed magnetic fields that SHOULD be creating voltages high enough to
do the job have any effect? What am I missing here?