Wednesday, May 19, 2010

Book Review: The Matchbox that Ate a Forty-Ton Truck by Marcus Chown

Marcus Chown has a marvellous gift for rendering cutting-edge science extremely accessible and entertaining. His latest work, "The Matchbox that Ate a Forty-Ton Truck," is a brilliant excursion through everyday life, showing what we might learn about the universe from things we see around us, including our own reflections in window glass, the variety of chemical elements, darkness at night and so forth. From simple phenomena, Chown transports readers on spectacular journeys through the realms of quantum physics, cosmology and other topics in modern science, explaining difficult concepts in a clear, methodical fashion. He weaves each tale with fascinating and humorous anecdotes about pivotal figures such as Fred Hoyle, Wolfgang Pauli and many other scientific luminaries. "Matchbox" will truly ignite your interest in science! Highly recommended!

Saturday, May 1, 2010

The Cave of Portents

Author's Note: I wrote this short fictional piece in 1999 as part of the same project that led to my book "The Pursuit of Destiny: A History of Prediction."

THE CAVE OF PORTENTS by Paul Halpern (1999)

Deep within the cave of portents, carved out over the eons by the currents of possibility, lies a chamber known for its auspicious acoustic qualities. Explorers stumbling upon that cavern have reported hearing beautiful melodies played out among the stony columns like the sonorant tones of wind chimes. Some have also recalled hearing soft whispering sounds, almost like the murmur of human voices. They have attributed these strange phenomena to peculiar resonant effects--a remarkable auditory illusion.

What makes matters even more intriguing are the presence of rocky formations in the chamber that seem to resemble human visages. Throughout the years since the cave was discovered, adventurers have nicknamed each of the stone faces after a historical or scientific figure.

One explorer, with a passion for philosophy, nicknamed one of the figures, “Pythagoras,” and another neighboring image, “Cicero,” because of their marked resemblances to those illustrious personages. A German exchange student, who gained admission to the caves as part of a summer research project, dubbed a craggy pillar close to the others, “Johannes Kepler,” after the 16th century astronomer of whose portrait it reminded him. A French spelunker, with a fondness for astrology, proudly selected the nickname “Nostradamus” for another rockface that seemed to have fiery, visionary eyes. Finally, to add to the eclectic mix of personalities, another caver, who knew modern physics very well, swore he saw the wild-haired image of Albert Einstein in one column, and the warm smile and deep, expressive glance of Richard Feynman in another.

With lanterns positioned well, these illusions were often enhanced by the strange rhythmic movements of shadows near the figures--suggesting the graceful gestures of musicians. Some have jokingly attributed the "concerts" and "conversations" seen and heard in the cavern to apparitions of the late scientists and philosophers, hovering near their stony likenesses. Hence the nickname for the chamber "harmony of the spirits."

Imagine the glorious music that would be made, and the striking and curious conversations that would resonate throughout the chamber, if the cave’s illusion suddenly and magically became real...

* * *

One Sunday morning, after an especially tuneful performance on his limestone "piano," the spirit of Kepler sighed and uttered, "Did you ever think we'd all end up here making music together?"

Nostradamus, who was chanting verses at the time, responded, "I knew. I pictured this strange cave, where great minds might harmonize, during one of my psychic excursions into the time of the third millennium. Like my other prophecies, it appeared to me during my nightly meditations upon water-filled glass. Through such exercises, I have witnessed all of history until the year 3797."

Cicero winced. "Another one of your preposterous claims. As usual, with unmatched zeal, but without a crumb of proof, you purport that the future is wholly predictable."

Nostradamus remarked in a huff, "It is predictable only to those who possess the powers of prophecy. Only those who lack the God-given vision to foresee the unraveling of the ages call my work preposterous."

At that point Pythagoras put down his lyre and joined in on the conversation. "Oh that vision thing again," he sneered. "You act as if the skill of foretelling the future is your exclusive domain. The gods have revealed man's destiny in the miraculous properties of numbers, and in the harmonious relationships between musical tones. Like a child taught the alphabet, any intelligent individual, properly trained in a superior academy, might be made aware of the wonders of the cosmos, deciphering its marvelous code."

Kepler spoke up. "Indeed, like Nostradamus, I've offered my share of horoscopes. The public expected me to provide such a service. But I've never claimed to be a prophet. My most fulfilling task, the discovery of the patterns of planetary orbits, I can attribute to my background in classical geometry. Simple, beautiful mathematics, not superstition, was the key to my success."

Pythagoras nodded his head. "Exactly. The cosmos is a vast fruit and mathematics is its pith. Those who peel off the outer layers of corporeal illusion, and savor the rich pulp of numerical truth, might truly taste their destinies."

Cicero looked up. "But what then. Suppose you use instinct, mathematics, examining animal entrails, or whatever your favorite method to discern the future. Does that mean, then, that you have discovered what must be in times to come or what could be in times to come? If you have found the former--the immutable future, then what's that point? What's the purpose of knowing something that you can't change? Just to be depressed? If Caesar knew his fate well in advance, but couldn't change it, perhaps he would have been an unhappy, ineffective leader. Bitter certainty would have engulfed him in a cloak of despair. And he would have been assassinated anyway.

On the other hand, if through your prognosticative abilities you have found mere possibilities or probabilities for the future--then there also would be no point. The winds of destiny could blow in another direction, and your prediction would be dead wrong anyway. You'd be chasing after specters in the dark, while reality passes you by."

Feynman, who had been banging his beloved bongo drums, glanced over when he heard the word "probability."

"Well that's all you can really know. Probabilities."

Cicero replied, "What do you mean?"

Feynman assumed his familiar pedagogical role. "Its too bad I don't have a blackboard here, but I'll try to explain without diagrams. Let me point out some of the ways classical physics and quantum mechanics fundamentally differ in how they treat basic interactions between particles. I’d like to consider the simple case of one electron exerting a force on another electron by means of exchanging a photon.

In classical physics, which is extraordinarily more intuitive than quantum theory, given their initial locations and speeds, one can map out the exact paths that the two electrons first take. Then one can examine how the first electron gives off a photon, and then recoils, like a gun firing off a bullet. Next, one can calculate precisely how the second electron absorbs the photon. Lastly, by means of the principles of conservation of energy and conservation of momentum, one can determine the ultimate trajectories and velocities of the particles. In short, by knowing the initial conditions one can infer exactly which routes are traveled, knowing with perfect precision the position and speed of each object for all times."

Kepler looked at Feynman and smiled. “Richard, I wish I could explain things so well. It all makes such perfect sense.”

Feynman chuckled. “Unfortunately everything I just said was wrong. Why? The reason is crazy, and I expect no one to believe it, not even the eminent thinkers in this chamber. Sometimes I don’t even know if I believe it myself. Physicists have given up to trying to predict anything exactly, because experimental evidence tells us that we just can’t do it. The uncertainty principle, a built in law of nature, restricts what we might know at any given moment. If we know a particle’s position perfectly well, then we don’t know its speed, and vice-versa.

In general, until we make an observation, all we can determine about a system is a set of probabilities. Then after we measure one particular quantity, the mere fact that we have observed the system shakes it up and affects its other properties, altering the probabilities that they have certain values. In other words, the future state of a system depends upon the choices made by observers.”

Kepler and Pythagoras exchanged puzzled glances. “But surely the magnificent harmony of nature has little to do with the decisions made by mortals,” stated Pythagoras.

“One would think,” replied the great theorist. “But one would get the wrong answer. For instance, in the scattering example I just mentioned one cannot assume that the electrons and photons followed only one trajectory. Rather, in quantum theory, one must consider the likelihoods of all possible exchanges between the particles, including bizarre situations such as photons traveling backward in time to meet electrons. Only by summing up these probabilities, in a special manner that takes a bit of mathematical juggling, might one be able to estimate likely outcomes.”

Kepler was intrigued, "Ah, I see. What I think you are saying, my spirited companion, is that nature is like a safe. To unlock its riddles, you must try each of the possible combinations it presents."

Feynman smiled. "Well, I would only need to try a few combinations--but I've had plenty of practice cracking open document drawers in Los Alamos. Nature, on the other hand, probes an infinite range of possibilities. But remarkably, one often can add up these infinite sums and obtain finite solutions to physical problems."

Einstein, who had been listening to the conversation while tuning his violin, looked dismayed.

"Ach, mein Freund. Gott ist im Himmel, nicht in Monte Carlo. Do you mean that there is only a finite probability that we are here, and that our energies might simultaneously occupy other configurations as well. Then how do we know precisely where we are?"

"Well if an observer were around to take a measurement of our locations, our wave functions might collapse to a particular position value. We may find ourselves still here, or conversely, we might not be here at all."

"An observer? Why, who might be here to observe us? I don't think anyone is paying attention to our proceedings?"

At that point the chamber became strangely silent. The winds seemed to shift, a lamp blew out, and the remarkable acoustical and optical illusions were no more.