X-Message-Number: 21055
From: "michaelprice" <>
References: <>
Subject: Electrons, Leptons & String Theory
Date: Tue, 4 Feb 2003 23:20:53 -0000

Thomas Donaldson writes:

> Sorry, Michael, but I was citing (as I think you know) some suggested
> theories which might join relativity and quantum theory. It is not
> that we could detect fundamentally different particles which we
> now see only as electrons, but that if electrons are composite then
> their energy levels in various situations might differ from those
> we'd expect if they were not composite.

True, but strictly speaking this is not relevant, unless you're arguing that
some electrons are composite and some are not (which you may well be,
of course).  More generally, though, energy levels in various situations may
differ between different composite particles.  Just as, say, composite
atoms may exist in a vary of excited states, which enables them to be
distinguished.  The question is, therefore, could there exist different
excited states of an electron due to its posited internal structure.
I take it this is what you mean by:

> They would be different in that sense.

But the differences would be so great that we would *already* classify
then as different particles.  It seems a concrete example is more persuasive
than an abstraction.  So.... let's assume string theory is correct, for the
purposes of this discussion.  According to string theorists the different
excited (vibrational) states of the string (with other properties held
constant) correspond to particles with different masses.  Hence they
would be classified as different types of particles.

> You are free to decide that the electrons are the "same",
> whatever that means. But if they have different traits (say, a
> property called "hyperspin") on different occasions, your thinking
> should take account of that.

Fine, but I argue that an electron's change in hypothetical "hyperspin"
would cause us to classify the changed particle as a new species.  It may or
may not be directly relevant to my string theory example above that there
*are* three "electrons" that differ only in mass.  We call them "leptons",
and they are, in mass order, the electron, the muon and the tau.  (This is
unlikely to be directly relevant since I think the different masses
generated by different string excitation levels differ by the order of a
planck mass or so, which is greater than the inter-lepton mass differences.
Still, it is suggestive.)

Robert Ettinger wrote, of my views:

> So, electrons do not and cannot have subspecies, and the same is true
> of elephants. I take this to mean that if two elephants are in the same
> quantum state, they are "identical."


> I see at least five things wrong with this.
> First, once more, it is just an arbitrary and unusual choice of language,
> no doubt protected in the U.S. by the First Amendment but not useful
> or appropriate. I repeat an earlier question: Is a gamma photon
> "identical" to a radio photon?

And I repeat my response.  Same as for orange vs red photons.
Perhaps you didn't see my cryoposts #20994 & #21020.

> Second, saying that two elephants are identical is really the claim that
> specifying the quantum state of a system tells you EVERYTHING there
> is to know about the system, [....]

Whoa!  Stop right there.  Saying two things are identical is NOT saying we
know everything about them, just that everything we know about one we also
know about the other.  Completely and crucially different.

As for the comparisons with Ptolemy's epicycles, see my response about the
robustness of quantum theory, cryopost #21027.

> Fourth--and I think this is most crucial for getting heads together--look
> again at this:
>> occupancy number of electron orbitals
>> is an absolute measure of the electron species number
> But the exclusion principle applies only to fermions, not to bosons.
> Bosons, including photons, can have many in the same state at the
> same time (lasers).

No this is not crucial, although it is true.  I could make all the same
points, but in a different way, for bosons, as I have for fermions.
Obviously occupancy of a bosonic state is not a measure of species
number, which is why I used the example of electrons (which are
fermions).  I mentioned Bose-Einstein condensates as an alternative
test for bosonic identity in cryopost #20884.

Your point is logically irrelevant, though, since we can
confine our discussion to just fermions (e.g. electrons) for ease of
explication.  (I presume you would not accept that fermions are identical,
whilst bosons are not?)

> Fifth, although this cuts no ice with some people, there is the
> "philosophical" problem with any fundamental indeterminacy.

You're right, that cuts no ice with me.  Hugh Everett III resolved these
problems, to my satisfaction.  See http://www.hedweb.com/manworld.htm

Michael C Price

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=21055