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!
So there is a branching event for you: if you survive a nuclear
blast, how sure could you be that you really survived?
Laurie Anderson was fond of saying: "What kills you is
not the bullett, its the hole!".
-Joao Leao
Hal Finney wrote:
> David Kwinter writes:
> > The concept of what makes a real quantum branch
> > irks me. Surely a man standing beside a nuclear explosion will never
> > survive.
>
> Not necessarily. What exactly kills a man standing by a nuclear
> explosion? Well, probably a lot of things, but let's think about the
> radiant heat energy released by the blast. This heat is carried by
> photons, each of which is emitted by some atom in the nuclear device.
> When an atom emits a photon, the direction of its emission is random.
> With the large numbers of atoms and photons involved, the emission is,
> on average, uniform in all directions, which is what we expect.
>
> But each individual emission is a quantum effect, and there is a chance
> that all of the atoms in the nuclear device could happen to emit their
> photons in a different direction than towards the man. In that case he
> would not experience the heat energy from the device and would not be
> killed by it.
>
> I think similar arguments are possible for the radiation and all other
> sources of destruction coming from the nuclear explosion. So a man
> standing beside such an explosion could in fact survive.
>
> It's also possible that the photons and other radiation from the device
> might happen to pass through the man's body without being absorbed.
> Each photon has a certain probability of being absorbed, per unit distance
> that it travels through biological tissue. And each absorption event is
> governed by quantum randomness. Therefore there is a nonzero chance that
> a photon could pass entirely through the man's body, and in fact that
> all of the photons could do so. In effect the man might just happen to
> become transparent at the precise instant necessary to survive the blast.
>
> Probably there are other bizarre quantum coincidences which could occur
> to let him survive as well.
>
> Hal Finney
--
Joao Pedro Leao ::: jleao.domain.name.hidden
Harvard-Smithsonian Center for Astrophysics
1815 Massachussetts Av. , Cambridge MA 02140
Work Phone: (617)-496-7990 extension 124
Cell-Phone: (617)-817-1800
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"All generalizations are abusive (specially this one!)"
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Received on Fri Oct 31 2003 - 13:36:52 PST