A theory ball is a collection of observations, explanations (causal
models), and predictions.

     A complete theory ball is considered to be perfectly round, and
indicates that every observation is explained, and every prediction is

     Where the theory ball is not round, then some observations are not
explained, or some predictions are not yet observed.

     The scientific method consists of the following sequence:

     Observation -> explanation -> prediction -> observation.

     Notice it is a circle.

     For example, light was observed to have different colors.

     This was explained by theorizing that light was a wave with
frequency, speed and wavelength, each color being a different frequency.

     People were already very familiar with wave mechanics through their
study of air and water.

     From this idea that light was a wave it was predicted that light
should show defraction (spreading) when sent through one slit and
interference patterns when sent through two slits.

     These predictions were then observed and thus became part of the
complete theory ball of light.

     Notice the above does not PROVE in any sense of the word that light
is in fact a wave, only that by assuming that light is a wave (the
explanation), one could make workable predictions that always turned out

     This is called the 'test of time'.

     However from the assumption that light was a wave, it was also
predicted that the wave must be a wave IN some medium, just as air waves
are waves in air, and water waves are waves in water.

     Both air and water waves exhibit diffraction and interference just
as light does, so it made sense to think that light might also travel in
a medium.

     Both air and water also have fixed speeds relative to the medium
they are traveling in, and so it was also predicted that light had a
fixed speed relative to the medium it traveled in.

     Both air and water also displayed Doppler shifts in speed.  When a
car is moving towards the source of a sound wave, not only is the
frequency perceived to be higher, but the speed of the sound wave
passing by the car is higher by the speed of the car.

     And when the car is moving away from the sound wave, the frequency
is perceived to be lower, and the speed of the wave passing by the car
is slower again by the speed of the car.

     It was therefore predicted that light should show the same

     The medium that light traveled in was called the aether and was
futher predicted to be the background fabric of space and time itself.

     Further since the Earth was moving like the car through that
background fabric, the measured speed of light should change depending
on how fast the Earth was moving through the medium.

     Since the Earth moves around the sun in a circle through out the
year, it should be found to be moving through the aether during most of
that time, except during a possibly very short moment when its speed
matched the aether, if it ever did.
     Remember the Earth is moving around the Sun, but the Sun isn't
still in any sense of the word, it is moving around the galaxy which
itself is moving at humongous speeds away from everything else.

     So frankly it was predicted that the Earth would never be found to
be moving at the same speed as the aether, but would every day be moving
at some slightly different speed relative to the background aether of
the universe.

     It was easy enough to find out the speed of light but the problem
was that the measured speed was the same no matter what direction it was
measured in, and no matter what time of year it was.

     Since the earth was moving at a significant speed through the
medium itself, then the speed of light should have reflected the speed
of the Earth, depending on the time of the year, as the Earth went
around the sun and completely changed directions.

     At first they theorized this observation was caused by the Earth
dragging the aether along with it, much as the Earth drags the
atmosphere along with i, so that at all times the speed of the Earth
relative to the aether was zero.

     But then they repeated the experiment with light coming in from the
moons of Jupiter as they orbited around the giant planet.  Light leaving
the moon as it moved away from Earth should be traveling slower than the
light leaving the same moon as it was approaching Earth on the other
side of Jupiter.

     But they got the same answer, the speed of light was constant no
matter how fast the source or observer were moving, or in what

     This could not be reconciled by the existing explanation that light
was a wave like air or sound.  In fact it couldn't be reconciled by any
existing theory of the time at all, it was so impossible that most
dismissed the observations as false and badly done experiments.

     Eventually Einstein came to the rescue with a 'new' explanation of
why the speed of light was constant, called the special theory of
relativity.  Things haven't been the same since.

     Light was a wave, but there was no medium, no aether, and measures
of space and time were relative to the speed different observers had

     Space and time obligingly 'adjusted' themselves to make sure that
the speed of light was always the same no matter the speed of the
observer or source.

     It was almost as if every observer/source pair lived in a universe
of its own where light automagically adjusted its speed to make the
speed of light the same no matter where it was measured from.

     But people no longer worried about the physical significance of
theories any more, physics was very happy and great things came of
special relativity over time.

     So the theory ball of light was round and complete again, all
observations were explained, and all predictions were observed.

     However a few years later another observation was made about light
that once again threw the whole world into chaos.

     This was the photo electric effect.

     When light is shined on a metallic surface electrons are freed from
the surface with an energy equal to the energy of the light shining on
the metal minus the energy it took to escape the metal's hold.

     The problem was, with a wave, the 'energy' of the wave is usually
considered to be the sum total energy of the whole wave.  Thus the
prediction was that by shining a brighter light of the same frequency on
the metal, more energy was hitting it, and more higher energy electrons
should come off.

     What they found instead was that below a certain frequency
electrons did not come off the metal at all, no matter how bright the
light was.  And yet above a certain frequency electrons started coming
off the metal no matter how dim the light was.

     This was definitely not wave like behavior.  But then light was
already pretty weird so people set about trying to explain these
observations, as clearly the predictions were wrong.

     Einstein again came to the rescue by suggesting that light was not
a wave but a particle called a photon, and each particle had an energy
proportional to its frequency.

     Only one photon was involved in the release of one electron from
the surface of the metal, and if the photon's collision with the metal
did not have the required energy, no electrons would be freed no matter
how many photons were hitting that electron at once.

     This is counter intuitive.  Consider being hit by a one pound ball
of lead, that would hurt, right?

     Now consider being hit by a ping pong ball.  That wouldn't bother
you, right?

     But now consider being hit by a million ping pong balls all at
once.  That would bother you right?

     But not so the electron, the electron didn't care how many half
pint photons hit it, but all it took was one full pint photon and out of
orbit the electron went.

     In other words photons were not additive the way waves and ping
pong balls are.

     So if the photons did have a higher freqency and thus a higher
energy, then each photon would release one electron from the metal
surface at an energy equivalent to the energy of he absorbed photon,
minus the escape energy of the electron from the metal.

     This indicated that whatever light was, it could only transfer
energy to electrons in finite quanta of energy, which was the energy of
the photon and that energ was a funcition of its COLOR not its INENSITY.

     With this understanding that light was a wave when looked at on a
macro scale, but a particle when looked at on a micro scale, the theory
ball once again became round and complete.

     All observations explained, and all predictions observed.

     But then someone chimed up and destroyed the happiness.  He said
remember that waves show diffraction and interference patterns when sent
through two slits but particles don't.  This is because waves interfere,
crests add with troughs to cancel out, particles don't have this wave
like propensity, so they don't.

     So now we know that light is a particle at the micro scale, how
come it produces diffraction and interference patterns when sent through
two slits?

     Worse one day, someone got real ornery and decided to really bring
the point home.  He built a long pipe with two slits at the far end.

     He made sure that the source of the light was so dim that only one
photon could be in the pipe at any one time, and thus there was no
possibility that any photon going through the right slit would ever meet
up with another photon going through the left slit and thus cancel
producing an interference pattern.

     He thus predicted that since light is a particle at the micro
scale, and surely one photon is micro scale, that it ought to act as a
particle and go through either the right or the left hand slit and not
produce an interference pattern on the other side.

     Interference patterns are only produced when TWO parts of a wave go
through TWO slits AT THE SAME TIME and thus cancel AT THE SAME TIME at
the phosphor screen at the far end.

     So he did the experiment predicting no interference patterns, but
lo and behold there it was, an interference pattern.

     If God was wise, he was obviously also a jerk.

     Was the SINGLE photon going through BOTH slits at once?

     How could it go through both slits, if it were a particle?  It
could only go through both slits at once if it were a wave, then it
could interfere with itself.

     Well it took a while, but eventually they came up with a final
theory which is now of course called quantum mechanics.  Quantum
mechanics has been hailed as the most universally workable theory human
kind has every devised to explain anything, the products of its genius
are all around us, cell phones, TV's, computers, you name it.

     But any quantum physicist will tell you that quantum mechanics is
also the first theory that no one on Earth has a clue what it is saying.

     Well its actually the second, special relativity was the first.

     Roughly what quantum mechanics is saying about light, is that light
is neither wave nor particle, but a probability which is spread out over
space and time, concentrated and high at some points, and defuse and low
at others.

     Thus as the light wave approaches the two slits, it has a
probability of going through either slit that is non zero.  The
probabilty wave will probably be higher for one slit than the other, but
will always have some finite probability at both, even if the photon is
aimed way off course from both slits.

     The probability wave thus does go through both slits and thus
interfers with itself, thus producing interference patterns.  The photon
only stops being a probability and becomes an actual photon when it
needs to, namely when it finally hits the phosphor screen on the other
side and has to make it glow.

     So that made everyone happy and they chattered about it on their
cell phones and video cameras, until one day someone thought to carry
the experiment further.

     They put a sensor on each side of the two slits which would detect
the photon passing through the slit and thus report if it was in fact
going through both, or just one.

     They had to know, it was driving them crazy.

     So they set up the same experiment with the sensors in place but
turned off, and there was the interference pattern indicating that the
single photons were going through both slits at the same time.
     Remember there was only one photon in the tube at a time.

     Then they turned the sensors on, and suddenly the interference
pattern vanished and started to look like a simple spread as if light
really was a particle going through one slit or the other but not both.

     The sensors reported this very same fact and for every photon that
went through the slits, the sensors could tell exactly which slit the
photon went through.  They were not going through both.

     But turn the sensors off, and the interference pattern came back.

     It seemed like trying to detect which slit the photon went through
forced its probability wave to decide before it entered the slit that
it was going to be left or right.

     But turn the sensors off and the decision was never made until it
hit the phosphor screens where it was too late to avoid self

     They still haven't explained this one to this day, oh yeah there
are lots of theories to explain it, each one more incomprehensible than
the one before it, and the real sign of how bad it is, is that the
various camps holding each theory aren't even on talking terms with the

     "Yours is more incomprehensible than mine!"

     You will find most of them playing Jacob's Ladder with string

     Such is the state of knowledge today about the nature of light,
the theory ball isn't quite round yet.


Homer Wilson Smith     The Paths of Lovers    Art Matrix - Lightlink
(607) 277-0959 KC2ITF        Cross            Internet Access, Ithaca NY    In the Line of Duty

Mon Feb 26 22:54:31 EST 2007