From: Wayne Hayes (wayne@cs.toronto.edu)
Date: Tue Dec 16 1997 - 10:08:46 MST
"Harry S. Hawk" <habs@panix.com> quotes Philip W Chao:
>> X-Sender: pcchao@pop.erols.com
>> ... However about 1 in 10 ** 23 atoms in your brian will align with
>> the magnetic field when you go into the scanner. That does change
>> the quantum state of the atoms - (only those that align) - but that
>> has not effect anything important.
I don't have numbers handy, but I would be *very* surprised if the
number was that small, because that's about 1 atom per mole, or about
1 atom per gram (give or take an order of magnitude). Given that the
brain weighs only a few kg, that's saying that only about 10,000-100,000
atoms are aligned. That's a pitifully small number of atoms, and I
suspect that it's far too few by many orders of magnitude for an MRI
scanner to do it's job. I could be wrong, but I'd like to see a
reference for this quote.
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