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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