X-Message-Number: 14194
Date: Fri, 28 Jul 2000 12:36:30 EDT
Subject: Clark,Pauli

It gets pretty tedious, but it has a certain morbid fascination--why certain 
mind-sets seem impervious to reason, or slaves to language.

John Clark is a fine fellow, doubtless with many virtues and abilities that I 
lack, but he seems to be stuck in a rut on the question of "identity of 
indiscernibles." (It's true he has the company of some distinguished people 
in this view.)

In the second place (#14187), he says that instantly switching locations of 
otherwise indistinguishable systems "happens all the time in the quantum 

How very strange! By his own account, you never know (for example) which 
electron is which, so how could you know they switch places--or why would it 
even be meaningful to say they switched places??!!

In the first place, he cites the Pauli exclusion principle as one of the 
proofs of identity of indiscernibles. If anything, it proves the opposite!

The exclusion principle says, for example, that you can't have two electrons 
in the same quantum state in the SAME ATOM. In the lithium atom, you can have 
two electrons in the lowest energy state, one spin up and one spin down; the 
third electron has to go into the next orbital. But there are lots of lithium 
atoms, each with its own electrons, so if we disregard which atoms we are 
talking about, there are plenty of lithium-attached electrons in the "same" 
quantum state--if we disregard the phase space coordinates of the atom as a 
whole, which is precisely what I argue we cannot do, in general.

In any case, when we talk about the "identity" of duplicate or similar 
people, the quantum states are never exactly the same, since merely being at 
a different location, in space or time, will instantly change the environment 
and therefore the system, albeit not necessarily a great deal, and we have 
the same old philosophical problems, which remain unsettled.

Robert Ettinger
Cryonics Institute
Immortalist Society

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