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09/05/2002
Waves
I once shook hands with Lionel Hampton, whose mallets elicited
those vibrations and the resulting sound waves beloved by jazz
enthusiasts everywhere. For me, waves are a problem. It stems
back to my youth when we lived for a short time in Atlantic City.
Riding the waves in to shore, it was obvious that a wave carries
with it a lot of water. Otherwise, why would so much water
wash up on the shore and then retreat before the next wave came
along? Yet, except when they break, waves carry little or no
water with them. Even those monstrous tsunamis, so-called tidal
waves generated by underwater earthquakes and hurricanes,
travel over open ocean without being accompanied by any
significant volume of water. The wave is just a rising and falling
of the water level, with its energy transferred from water
molecule to water molecule as the wave moves along. Tell that
to the residents of Lisbon, Portugal, which was devastated by a
50-foot wall of water in 1755! The energy in that wave can grow
into something truly awesome when transferred to shallow water.
The sound waves from Hampton''s vibraphone were the
compression and spreading out of air molecules generated by the
vibrations of the instrument''s keys. Sound waves can also travel
through a medium other than air. Otherwise, even with my
windows closed, those blasted redeye flights from California
wouldn''t wake me up at 5 AM on their way to land at nearby
Newark Airport. To propagate, sound waves need some kind of
medium in which to travel through - air, wood, metal, water, etc.
Electromagnetic waves are different. They, in effect, supply
their own medium. Light and radio waves are prime examples.
We see light from distant galaxies that has traveled trillions upon
trillions of miles through empty space and we communicate with
spacecraft like the Voyager out at the limits of our solar system.
Even if we don''t understand it, we accept the fact that radio
waves travel through walls and light waves travel through glass.
With light, however, it isn''t that simple. Experiments had shown
that light consisted of waves. Other experiments showed light to
be made up of particles. In 1923, Louis de Broglie proposed that
any material particle should have properties of a wave associated
with it. In the year I was born, 1927, Clinton Davisson and a
colleague at Bell Labs showed that electrons behaved as waves
in a landmark experiment. That same year, Werner Heisenberg
came up with his Uncertainty Principle, which stated that you
can''t measure exactly the position and velocity (actually,
momentum) of an object at the same time. He deduced that the
very act of observing one quantity affected how precisely you
could determine the other. Meanwhile, in 1926, Erwin
Schrodinger came up with the Schrodinger wave equation, the
basic equation that would drive quantum mechanics. All of these
fellows eventually won Nobel Prizes.
With the small-scale quantum mechanical world firmly
established, it was generally agreed that, strange as it seemed,
light, electrons and other fundamental building blocks were both
particles and waves. The world was also now filled with
uncertainty and you had to rely on statistics and solutions of
Schrodinger''s equation to calculate probabilities of where things
were and where they were going. This world of electrons and
atoms and light was like nothing related to our everyday life.
This view of the world was championed by the Danish physicist
Niels Bohr, winner of the Nobel Prize in 1922 for his role in
proposing that an atom was like a solar system of electrons
whizzing around a nucleus. Bohr seized upon Heisenberg''s work
to push the "Copenhagen Interpretation" of quantum mechanics,
stressing its statistical nature and uncertainty.
Not everyone agreed with this view. Einstein and even
Schrodinger were not happy with the Copenhagen approach and
its reliance on statistics and mathematics. In Einstein''s view, the
mathematical equations, while useful and productive, hid our
ignorance about the actual physical nature of fundamental
"particle/waves". Einstein''s famous remark that he didn''t think
that God rolled dice summed up his disagreement with Bohr.
However, Bohr and the Copenhagen school won out. Later,
Richard Feynman was to remark that on a small scale things
behave like nothing we''ve had any experience with and that we''d
better "get used to it."
Enter Carver Mead who doesn''t think we have to get used to it.
Last May, at The Electrochemical Society''s centennial meeting
in Philadelphia, he was one of our plenary lecturers. Mead is an
emeritus professor at the California Institute of Technology,
where he''s spent some four decades. Not your run-of-the-mill
academic, Mead has been one of the superstars of Silicon Valley
whose fundamental concepts and devices have supported and
spurred the electronics age. With more than 50 patents, he has
started 25 companies, ranging from a company making touch
pads for laptop computers to Foveon, a recently formed company
that has begun to market a revolutionary digital camera. (This
camera utilizes an ingenious design of silicon chip that allows
one pixel to display the true color. Normally, three pixels are
required - one each for the red, blue and green.)
In Philadelphia, Mead, dressed casually in typical Valley fashion,
talked about the future of solid state science and technology but
didn''t mention his views on waves. Recently, Brian Trumbore
called my attention to an interview with Mead that had appeared
in the September/October 2001 American Spectator. The
interview left me stunned and better informed about the
conflicting views on quantum mechanics cited above.
Let''s consider some of the baggage that accompanies quantum
mechanics. One example is "tunneling". Mead spent a decade
working on tunneling and a device called a tunnel diode. I had
some experience with tunnel diodes, having provided materials
to our device people at Bell Labs for these devices. Tunneling
involves a particle, say an electron, moving in some strange way
through an energy barrier to appear on the other side. It''s as
though you came to a wall and walked right through it.
Tunneling was certainly a mystery to me. Now, Mead says that
there''s nothing mysterious about it. It''s just like a radio wave
moving through a wall, only on a vastly smaller scale.
Other baggage includes the Heisenberg Uncertainty Principle
itself. I was amazed to read that Mead claims we have violated
that principle, the laser being just one example. In a laser, all the
crests and troughs of the light waves are lined up precisely. We
seem to know just where the waves are and how fast they''re
moving. According to the article, Bohr came to Columbia in
1956 to visit the lab of Charles Townes to see his newly invented
laser. Bohr apparently didn''t believe that a laser was possible.
Today''s billions of lasers in CD players and many other
applications have proved Bohr wrong.
To me, the most unbelievable baggage associated with quantum
theory is the so-called "entangled" particle business. Let''s say
that a pair of particles has something called "spin" and that when
they''re "entangled" one particle has a spin of 1 and the other has
a spin of 0. Let''s send one particle out to the Andromeda galaxy
and keep the other nearby. Experiments in the past few years
reputedly confirm that if we measure the spin of the particle here
as 1, the spin of the other particle will be 0, no matter how far
away it is. Or vice versa, the implication being that you could
affect the distant particle''s spin by altering the spin of the handy
nearby particle. Although the Spectator interview doesn''t give
details, Mead supposedly can explain this handily.
In the Spectator interview, Mead does away with the baggage of
the particle/wave and seems to say, "Forget the particle - it''s the
wave." Everything is waves. He says that those experiments
showing light to be particles were using instrumentation that was
crude by today''s standards. Mead does not claim to have solved
"everything" and says physicists are farther away from their long
sought theory of everything than they think. And, picture this,
Mead says that since waves spread out to fill their container, an
electron, being a wave, can be a foot long or even a mile long,
depending on the size of its "box"! Now I''m really in trouble. I
can''t even understand a simple wave in the ocean!
Finally, for those who read last week''s column, I''m happy to
report that Andy and Dana are now legally man and wife after
surviving both Cambodian and Slovak weddings!
Allen F. Bortrum
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