Re: Polarization is digital, sort of

Steve Witham (
Mon, 28 Apr 1997 01:28:00 -0400

>If a beam of light is polarized at 0 degrees and you set your polarizer at
>X degrees then the number of photons in the beam will be reduced by
>[cos(X)]^2, for 45 degrees that is 50%. For an individual photon there is a
>50% chance it will make it through and a 50% chance it will not, if it does
>make it through the amplitude has not been changed at all[...]

Just want to point out that the 50% probability of the photon getting through
is determined by something called a "probability amplitude," which (in
this example) *is* (a complex number with an absolute value of) .707...

I mean, the (okay, well, a) wierd thing to me is how the good old electrical
ideas of amplitude and power are still there, with power being the square
of the amplitude, only now power is likely number of (or chance of) photons
and amplitude is this strange complex number that spreads out just like
an electromagnetic wave, getting diffracted and reflected and refracted
and interfering with itself...until it comes to some place where you *look*
at it, at which point (and only at that point) you have to *square* it to
get a probability. Brr.

I mean, like, power is the square of amplitude because voltage both
pushes more electrons through a resistor and means each electron does
more work. But what's the equivalent of current and voltage for
probability, you know what I'm sayin'?

Of course it all makes "sense" if you look at it as a wavefunction within
which (if you're so inclined) you can see a structure of branching universe
histories, from within "most" of which life seems to obey rules of physics
with some constrained chance thrown in...

Anyhow, if reality is digital, how come it keeps splitting into branches
at such an alarming rate, without getting any grainier-looking in the
process? I mean, with an infinite supply of bits you might as well be
analog, if you know what I mean.


--           Steve Witham          web page under reconsideration