Re: Two-slit experiment

On Tue, 1 Aug 2006, Oz wrote:

Timo A. Nieminen <timo@xxxxxxxxxxxxxxxxx> writes

1) Use EM waves where hf >> energy required to "click" the detectors.

Yes.

2) Count for long enough (both with and without source) to get reliable
statistics.

Yes.

3) Energy required to "click" detectors >> kT

.. which is the point of using a gamma source.

and this shows what, exactly?

Remember pretty well all transitions are effectively tuned,
which is why we can use very low intensity em waves and still get
transitions.
[cut longer discussion of this point]

(a) If the energy is spread out evenly, as suggested by classical EM
theory, and only a small fraction of that energy is required for
detection, then the surplus of energy should allow simultaneous detection
in two locations, given classical light.

(b) I think that it's sufficient to do this with hf = detector-tripping
energy. However, some might argue that the detector magically sucks in all
the energy at the instant of detection, even from distances of up to at
least 2 times the distance to the source. Even if this is, eg, many
light-years. Given the relativity of simultaneity, instantaneous action
over an extended region is problematic, at best. hf >> detection energy
doesn't leave this weaseling-out space.

A "quantumist" would say that the detection is an inelastic collision
between a photon and a detector, so perhaps it doesn't show anything that
the Compton effect doesn't already show.

I would argue, at least to me its the simplest solution, that the very
existence of diffraction, and its properties, show that light goes
through both slits at once. That is, its in two different places at
once. I could attenuate a laser beam so as to get only one detection per
hour and I would still get a diffraction pattern.

Your photon is of course a convenient mathematical tool. You define it
to be pointlike and then ask me to prove it isn't. Diffraction shows
that it cannot be pointlike, although using the correct mathematical
tools you can use such an animal to emulate a large wave. This is often
a most convenient methodology.

Diffraction shows that _EM waves_ are not pointlike. Pointlike detection
shows that the energy, at small amplitudes is not detected as being evenly
spread over a large volume as classically predicted.

But many are happy to (a) accept that electrons are point particles, and
(b) the probability of detection of them as a function of position is
given by the wavefunction. The alternative I'm arguing against (ie
electron = wavefunction of electron, electron has a size = spread of
wavefunction) requires the electron to shrink to a pointlike size
instantly on "detection of position", even if, eg, the wavefunction
"extended" for many km (note: technically, the wavefunction extends over
all space and all time, though it might have values of zero for some
positions and some times - I think that this makes wavefunctions look even
more like convenient mathematical tools than pointlike electrons).

Replace electron with photon, wavefunction with EM wave, and ditto.

Diffraction + pointlike detection shows that light is not photons, and
that light is not a classical EM wave. Oops! Nature turned out to be
stranger than expected.

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html

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