Hal Finney wrote:

> Joao Leao, <[EMAIL PROTECTED]>, writes:
> > You are quite right in one point,  Hal: "...probably a lot of
> > things!".  But you should have written: "Certainly
> > a lot of things, each one with high probability". If you pick
> > photons  rather than, say, flying massive debris, you should
> > in all honesty, include photons along all the spectrum
> > including, of course, gamma rays, which will kill you not
> > just now, but keep on killing softly you forever by blasting the
> > nuclear structure of your atoms and persuading them to
> > decay. You would conclude that if you survive the blast,
> > you would, with the help of QM  be able to calculate precisely
> > how dead  you already are!
> I'm not sure if you are joking here; do you agree that even gamma
> ray photons may happen to miss your body due to the quantum randomness
> in their emission and absorption events?

I was joking but not entirely. It is very tempting for people to talk
"quantum probabilism" in the way you do here, that is, by using an
analogy with classical equilibrium statistical emsembles where even the
improbable event has a small but non infinitesimal chance of occurring.
This, however is incorrect. Unlike Stat Mech,  Quantum mechanics can,
and does, predict definite events (with prob=1) and does so in many
classical situations where classical mechanics cannot not!  Yakir Aharonov

and his students made and artform of discovering examples of this style
of Quantum Magic!... The thing is: QM probability distributions
evolve in time and most spectra are discrete... so this fetching world of
monkeys and typerwiters does not apply.

My point is that, probabilistically or otherwise, a gamma ray kills you
much more surely than any single bullet if you compare not only
the scattering corsssections  but also the long term effects. That may
have something to do with the fact that "gamma emmiters" are under
stricter control than handguns...

> > So there is a branching event for you: if you survive a nuclear
> > blast, how sure could you be that you really survived?
> Which brings up another possibility, which is that your body could
> spontaneously re-assemble from atoms in the environment even if it were
> temporarily destroyed.  In that case you might have genuine uncertainty
> as to whether you really survived, depending on your views of personal
> identity and survival.

Now, that is a joke! Wait! I think that just happened to me!

> Hal




Joao Pedro Leao  :::  [EMAIL PROTECTED]
Harvard-Smithsonian Center for Astrophysics
1815 Massachussetts Av. , Cambridge MA 02140
Work Phone: (617)-496-7990 extension 124
Cell-Phone: (617)-817-1800
"All generalizations are abusive (specially this one!)"

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