OTish :D Colors of Cases for Fedora was: Re: Open Letter

[Don Quixote de la Mancha]

It is true that flat-black materials are the strongest radiators.

If you know the reflectivity of a material, you can measure its
temperature from the flux of light (or infrared, for normal
conditions) emitted per unit area from its surface.  For a given
temperature, the higher reflectivity will emit less.

Even if you don't know the reflectivity - say, if you're taking an
aerial or satellite photo - you can still measure the temperature by
using a spectroscope to find the wavelength (or color) of the emission
peak.  As materials grow warmer, their emission grows both brighter
and bluer.  Thus hot stoves glow deep red, while lightning bolts are
blueish-white and colossally bright.

Interestingly, the physicist Planck derived that emission spectrum
from purely classical considerations of systems of harmonic
oscillators.  I'm afraid I don't recall the derivation, but it has the
curious property that it explains a fundamentally quantum mechanical
phenomenon without the use of any quantum mechanics in the derivation.
 Purely classical!

Planck's Constant h is found in the function that describes that
spectrum, and can be calculated from that derivation.

What is really cool is that Planck's Constant is also found throughout
quantum mechanics.  In QM h is almost always divided by 2 * PI, so to
save writing we write an h with a diagonal slash through it, then drop
the 2 * PI.  This is pronounced "h bar".

Now here is where it gets really bizarre: h bar divided by two is the
spin of the electron!  That is, when we say that electrons are spin
one-half particles, we mean that their angular momentum is h bar
divided by two.  Spin one particles like photons have an angular
momentum of one h bar.

It took me a long, long, long time to come to grips with spin.  Spin
is angular momentum, and charged particles that have spin exhibit the
magnetic fields that one would expect from rotating electric charges,
but spin is NOT rotation.

Spin is also quantized.  If we subject an electron to a magnetic
field, its magnetic pole will either line up with the applied field,
or opposite to it.  Only these two choices are permitted; nothing in
between.

Bound states of particles are individual particles themselves.  They
obey all the same laws as elementary particles, just in more complex
ways.  Thus rotation arises from systems of lots of particles that
possess some kind of spin.

A friend describes spin as "an irreparable tear in the fabric of the Universe".

My Fedora case is black, but that's just because I wanted a case with
ten drive bays, and the only ten bay case that Central Computers had
in stock was black.  That allows for a burner, a floppy, and
(eventually) and eight-disk RAID.  I only have four disks so far, but
I'm planning for the future.

It's been a long, long time, and I've forgotten all but the conceptual
bits, but at one time I was an Astronomy major at the California
Institute of Technology.

Mike
-- 
Don Quixote de la Mancha
quixote at dulcineatech.com
http://www.dulcineatech.com

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