Physics of the Impossible Part 11

Some physicists have taken this idea even further, to the very limits of science fiction, in asking whether intelligence may have had a hand in designing our universe.

In the Guth/Fahri picture, an advanced civilization can create a baby universe, but the physical constants (e.g., the ma.s.s of the electron and proton and the strengths of the four forces) are the same. But what if an advanced civilization could create baby universes that differ slightly in their fundamental constants? Then the baby universes would be able to "evolve" with time, with each generation of baby universes being slightly different from the previous generation.

If we consider the fundamental constants to be the "DNA" of a universe, it means that intelligent life might be able to create baby universes with slightly different DNA. Eventually, universes would evolve, and the universes that proliferated would be those that had the best "DNA" that allow for the flouris.h.i.+ng of intelligent life. Physicist Edward Harrison, building on a previous idea by Lee Smolin, has proposed a "natural selection" among universes. The universes that dominate the multiverse are precisely those that have the best DNA, which is compatible with creating advanced civilizations, which in turn create more baby universes. "Survival of the fittest" simply means survival of the universes that are most favorable to producing advanced civilizations.

If this picture is correct, it would explain why the fundamental constants of the universe are "fine-tuned" to allow for life. It simply means that universes with desirable fundamental constants compatible with life are the ones that proliferate in the multiverse.

(Although this "evolution of universes" idea is attractive because it might be able to explain the anthropic principle problem, the difficulty with this idea is that it is untestable and unfalsifiable. We will have to wait until we have a complete theory of everything before we can make sense out of this idea.) Currently, our technology is far too primitive to reveal the presence of these parallel universes. So all this would qualify as a Cla.s.s II impossibility-impossible today, but not in violation of the laws of physics. On a scale of thousands to millions of years, these speculations could become the basis of a new technology for a Type III civilization.

14: PERPETUAL MOTION MACHINES.

Theories have four stages of acceptance: i. this is worthless nonsense; ii. this is interesting, but perverse; iii. this is true, but quite unimportant; iv. I always said so.

-J. B. S. HALDANE, 1963.

In Isaac Asimov's cla.s.sic novel The G.o.ds Themselves, an obscure chemist in the year 2070 accidentally stumbles upon the greatest discovery of all time, the Electron Pump, which produces unlimited energy for free. The impact is immediate and profound. He is hailed as the greatest scientist of all time for satisfying civilization's unquenchable thirst for energy. "It was Santa Claus and Aladdin's lamp of the whole world," Asimov wrote. The company he forms soon becomes one of the richest corporations on the planet, putting the oil, gas, coal, and nuclear industries out of business.

The world is awash with free energy and civilization is drunk with this newfound power. As everyone celebrates this great achievement, one lone physicist is uneasy. "Where is all this free energy coming from?" he asks himself. Eventually he uncovers the secret. The free energy comes with a terrible price. This energy is pouring in from a hole in s.p.a.ce connecting our universe to a parallel universe, and the sudden influx of energy into our universe is setting off a chain reaction that will eventually destroy the stars and galaxies, turning the sun into a supernova, and destroying the Earth with it.

Since recorded history, the holy grail for inventors, scientists, as well as charlatans and scam artists has been the fabled "perpetual motion machine," a device that runs forever without any loss of energy. An even better version is a device that can create more energy than it consumes, such as the Electron Pump, which creates free, limitless energy.

In the coming years, as our industrialized world gradually runs out of cheap oil, there will be enormous pressure to find abundant new sources of clean energy. Soaring gas prices, falling production, increased pollution, atmospheric changes-all are fueling a renewed, intense interest in energy.

Today a few inventors riding this wave of concern promise to deliver unlimited quant.i.ties of free energy, offering to sell their inventions for hundreds of millions. Scores of investors periodically line up, lured by sensational claims in the financial media that often hail these mavericks as the next Edison.

The popularity of perpetual motion machines is widespread. On an episode of The Simpsons, ent.i.tled "The PTA Disbands," Lisa builds her own perpetual motion machine during a teachers' strike. This prompts Homer to declare sternly, "Lisa, get in here...in this house we obey the laws of thermodynamics!"

In the computer games The Sims, Xenosaga Episodes I and II, and Ultima VI: The False Prophet, as well as the Nickelodeon program Invader Zim, perpetual motion machines figure prominently in the plots.

But if energy is so precious, then precisely what is the likelihood of our creating a perpetual motion machine? Are these devices truly impossible, or would their creation require a revision in the laws of physics?

HISTORY VIEWED THROUGH ENERGY.

Energy is vital to civilization. In fact, all of human history can be viewed through the lens of energy. For 99.9 percent of human existence, primitive societies were nomadic, scratching a meager living scavenging and hunting for food. Life was brutal and short. The energy available to us was one-fifth of a horsepower-the power of our own muscles. a.n.a.lyses of the bones of our ancestors show evidence of enormous wear and tear, caused by the crus.h.i.+ng burdens of daily survival. Average life expectancy was less than twenty years.

But after the end of the last ice age about ten thousand years ago, we discovered agriculture and domesticated animals, especially the horse, gradually raising our energy output to one or two horsepower. This set into motion the first great revolution in human history. With the horse or ox, one man had enough energy to plow an entire field by himself, travel tens of miles in a day, or move hundreds of pounds of rock or grain from one place to another. For the first time in human history, families had a surplus of energy, and the result was the founding of our first cities. Excess energy meant that society could afford to support a cla.s.s of artisans, architects, builders, and scribes, and thus ancient civilization could flourish. Soon great pyramids and empires rose from the jungles and desert. Average life expectancy reached about thirty years.

Then about three hundred years ago the second great revolution in human history took place. With the coming of machines and steam power, the energy available to a single person soared to tens of horsepower. By harnessing the power of the steam locomotive, people could now cross entire continents in a few days. Machines could plow entire fields, transport hundreds of pa.s.sengers thousands of miles, and allow us to build huge towering cities. Average life expectancy by 1900 had reached almost fifty in the United States.

Today we are in the midst of the third great revolution in human history, the information revolution. Because of an exploding population and our ravenous appet.i.te for electricity and power, our energy needs have skyrocketed and our energy supply is being stretched to the very limit. The energy available to a single individual is now measured in thousands of horsepower. We take for granted that a single car can generate hundreds of horsepower. Not surprisingly, this demand for more and more energy has sparked an interest in greater sources of energy, including perpetual motion machines.

PERPETUAL MOTION MACHINES THROUGH HISTORY.

The search for a perpetual motion machine is an ancient one. The first recorded attempt to build a perpetual motion machine dates back to the eighth century in Bavaria. It was a prototype for hundreds of variations to come for the next thousand years; it was based on a series of small magnets attached to a wheel, like a Ferris wheel. The wheel was placed on top of a much larger magnet on the floor. As each magnet on the wheel pa.s.sed over the stationary magnet, it was supposed to be attracted then repelled by the larger magnet, thereby pus.h.i.+ng the wheel and creating perpetual motion.

Another ingenious design was devised in 1150 by the Indian philosopher Bhaskara, who proposed a wheel that would run forever by adding a weight to the rim, causing the wheel to spin because it was unbalanced. Work would be done by the weight as it made a revolution, and then it would return to its original position. By iterating this over and over again, Bhaskara claimed that one could extract unlimited work for free.

The Bavarian and the Bhaskara designs for perpetual motion machines and their many descendants all share the same ingredients: a wheel of some sort that can make a single revolution without the addition of any energy, producing usable work in the process. (Careful examination of these ingenious machines usually shows that energy is actually lost in each cycle, or that no usable work can be extracted.) The coming of the Renaissance accelerated proposals for a perpetual motion machine. In 1635 the first patent was granted for a perpetual motion machine. By 1712 Johann Bessler had a.n.a.lyzed some three hundred different models and proposed a design of his own. (According to legend, his maid later exposed his machine as a fraud.) Even the great renaissance painter and scientist Leonardo da Vinci became interested in perpetual motion machines. Although he denounced them in public, comparing them to the fruitless search for the philosopher's stone, in private he made ingenious sketches in his notebooks of self-propelling, perpetual motion machines, including a centrifugal pump and a chimney jack used to turn a roasting skewer over a fire.

By 1775 so many designs were being proposed that the Royal Academy of Science in Paris stated that it would "no longer accept or deal with proposals concerning perpetual motion."

Arthur Ord-Hume, a historian of these perpetual motion machines, has written about the tireless dedication of these inventors, working against incredible odds, comparing them to the ancient alchemists. But, he noted, "Even the alchemist...knew when he was beaten."

HOAXES AND FRAUDS.

The incentive to produce a perpetual motion machine was so great that hoaxes became commonplace. In 1813 Charles Redheffer exhibited a machine in New York City that amazed audiences, producing unlimited energy for free. (But when Robert Fulton examined the machine carefully, he found a hidden cat-gut belt driving the machine. This cable was in turn connected to a man secretly turning a crank in the attic.) Scientists and engineers, too, got swept up in the enthusiasm for perpetual motion machines. In 1870 the editors of Scientific American were fooled by a machine built by E. P. Willis. The magazine ran a story with the sensational t.i.tle "Greatest Discovery Ever Yet Made." Only later did investigators discover that there was a hidden source of energy for Willis's perpetual motion machine.

In 1872 John Ernst Worrell Kelly perpetrated the most sensational and lucrative scam of his day, swindling investors of nearly $5 million, a princely sum back in the late nineteenth century. His perpetual motion machine was based on resonating tuning forks that he claimed tapped into the "ether." Kelly, a man with no scientific background, would invite wealthy investors to his house, where he would amaze them with his Hydro-Pneumatic-Pulsating-Vacuo-Engine, which whizzed around without any external power source. Eager investors, amazed by this self-propelled machine, flocked to pour money into his coffers.

Later some disillusioned investors angrily accused him of fraud, and he actually spent some time in jail, although he died a wealthy man. After his death investigators found the clever secret of his machine. When his house was torn down concealed tubes were found in the floor and walls of the bas.e.m.e.nt that secretly delivered compressed air to his machines. These tubes in turn were energized by a flywheel.

Even the U.S. Navy and the president of the United States were taken in by such a machine. In 1881 John Gamgee invented a liquid ammonia machine. The vaporization of cold ammonia would create expanding gases that could move a piston, and hence could power machines using only the heat of the oceans themselves. The U.S. Navy was so enthralled with the idea of extracting unlimited energy from the oceans that it approved the device and even demonstrated it to President James Garfield. The problem was that the vapor did not condense back into a liquid properly; hence the cycle could not be completed.

So many proposals for perpetual motion machines have been presented to the U.S. Patent and Trademark Office (USPTO) that the office refuses to grant a patent for such a device unless a working model is presented. In certain rare circ.u.mstances, when the patent examiners can find nothing obviously wrong with a model, a patent is granted. The USPTO states, "With the exception of cases involving perpetual motion, a model is not ordinarily required by the Office to demonstrate the operability of a device." (This loophole has allowed unscrupulous inventors to persuade naive investors to finance their inventions by claiming that the USPTO has officially recognized their machine.) The pursuit of the perpetual motion machine, however, has not been fruitless from a scientific point of view. On the contrary, although inventors have never produced a perpetual motion machine, the enormous time and energy invested in building such a fabled machine has led physicists to carefully study the nature of heat engines. (In the same way, the fruitless search of alchemists for the philosopher's stone, which can turn lead into gold, helped to uncover some of the basic laws of chemistry.) For example, in the 1760s John c.o.x developed a clock that could actually run forever, powered by changes in atmospheric pressure. Changes in air pressure would drive a barometer, which would then turn the hands of the clock. This clock actually worked and exists even today. The clock can run forever because energy is extracted from the outside in the form of changes in atmospheric pressure.

Perpetual motion machines like c.o.x's eventually led scientists to hypothesize that such machines could run forever only if energy was brought in to the device from the outside, that is, that total energy was conserved. This theory eventually led to the First Law of Thermodynamics-that the total amount of matter and energy cannot be created or destroyed. Eventually three laws of thermodynamics were postulated. The Second Law states that the total amount of entropy (disorder) always increases. (Crudely speaking, this law says that heat flows spontaneously only from hotter to colder places.) The Third Law states that you can never reach absolute zero.

If we compare the universe to a game and the goal of this game is to extract energy, then the three laws can be rephrased as follows: "You can't get something for nothing." (First Law) "You can't break even." (Second Law) "You can't even get out of the game." (Third Law) (Physicists are careful to state that these laws are not necessarily absolutely true for all time. Nevertheless, no deviation has ever been found. Anyone trying to disprove these laws must go against centuries of careful scientific experiments. We will discuss possible deviations from these laws shortly.) These laws, among the crowning achievements of nineteenth-century science, are marked by tragedy as well as triumph. One of the key figures in formulating these laws, the great German physicist Ludwig Boltzmann, committed suicide, in part because of the controversy he created in formulating these laws.

LUDWIG BOLTZMANN AND ENTROPY.

Boltzmann was a short, barrel-chested bear of a man, with a huge, forestlike beard. His formidable and ferocious appearance, however, belied all the wounds he suffered in defending his ideas. Although Newtonian physics was firmly established by the nineteenth century, Boltzmann knew these laws had never been rigorously applied to the controversial concept of atoms, a concept that was still not accepted by many leading scientists. (We sometimes forget that as late as a century ago there were legions of scientists who insisted that the atom was just a clever gimmick, not a real ent.i.ty. Atoms were so impossibly tiny, they claimed, that they probably didn't exist at all.) Newton showed that mechanical forces, not spirits or desires, were sufficient to determine the motion of all objects. Boltzmann then elegantly derived many of the laws of gases by a simple a.s.sumption: that gases were made of tiny atoms that, like billiard b.a.l.l.s, obeyed the laws of forces laid down by Newton. To Boltzmann, a chamber containing gas was like a box filled with trillions of tiny steel b.a.l.l.s, each one bouncing off the walls and each other according to Newton's laws of motion. In one of the greatest masterpieces in physics, Boltzmann (and independently James Clerk Maxwell) mathematically showed how this simple a.s.sumption could result in dazzling new laws and open up a new branch of physics called statistical mechanics.

Suddenly many of the properties of matter could be derived from first principles. Since Newton's laws stipulated that energy must be conserved when applied to atoms, each collision between atoms conserved energy; that meant that an entire chamber of trillions of atoms also conserved energy. The conservation of energy could now be established not just via experimentation, but from first principles, that is, the Newtonian motion of atoms.

But in the nineteenth century the existence of atoms was still hotly debated and often ridiculed by prominent scientists, such as philosopher Ernst Mach. A sensitive and often depressed man, Boltzmann uncomfortably found himself the lightning rod, the focus of the often vicious attacks by the anti-atomists. To the anti-atomists, anything that could not be measured did not exist, including atoms. To add to Boltzmann's humiliation, many of his papers were rejected by the editor of a prominent German physics journal because the editor insisted that atoms and molecules were strictly convenient theoretical tools, rather than objects that really existed in nature.

Exhausted and embittered from all the personal attacks, Boltzmann hung himself in 1906 while his wife and child were at the beach. Sadly he did not realize that just a year before, a brash young physicist by the name of Albert Einstein had done the impossible: he had written the first paper demonstrating the existence of atoms.

TOTAL ENTROPY ALWAYS INCREASES.

The work of Boltzmann and other physicists helped to clarify the nature of perpetual motion machines, sorting them into two types. Perpetual motion machines of the first type are those that violate the First Law of Thermodynamics; that is, they actually produce more energy than they consume. In every case physicists found that this type of perpetual motion machine relied on hidden, outside sources of energy, either through fraud, or because the inventor did not realize the source of the outside energy.

Perpetual motion machines of the second type are more subtle. They obey the First Law of Thermodynamics-conserving energy-but violate the Second Law. In theory, a perpetual motion machine of the second type produces no waste heat, so it is 100 percent efficient. Yet the Second Law says that such a machine is impossible-that waste heat must always be produced-and hence disorder or chaos in the universe, or entropy, always increases. No matter how efficient a machine might be, it will always produce some waste heat, thereby raising the entropy of the universe.

The fact that total entropy always increases lies at the heart of human history as well as mother nature. According to the Second Law, it is far easier to destroy than to build. Something that might take thousands of years to create, such as the great Aztec Empire in Mexico, can be destroyed in a matter of months; and this is what happened when a raggedy band of Spanish conquistadores, armed with horses and firearms, completely shattered that empire.

Every time you look in a mirror and see a new wrinkle or a white hair you are observing the effects of the Second Law. Biologists tell us that the aging process is the gradual acc.u.mulation of genetic errors in our cells and genes, so that the cell's ability to function slowly deteriorates. Aging, rusting, rotting, decay, disintegration, and collapse are also examples of the Second Law.

Remarking on the profound nature of the Second Law, astronomer Arthur Eddington once said, "The law that entropy always increases holds, I think, the supreme position among the laws of Nature...if your theory is found to be against the second law of thermodynamics, I can give you no hope; there is nothing for it but to collapse in deepest humiliation."

Even today enterprising engineers (and clever charlatans) continue to announce the invention of perpetual motion machines. Recently I was asked by the Wall Street Journal to comment on the work of an inventor who had actually persuaded investors to sink millions of dollars into his machine. Breathless articles were published in major financial newspapers, written by journalists with no background in science, gus.h.i.+ng about the potential of this invention to change the world (and generate fabulous, lucrative profits in the process). "Genius or crackpot?" the headlines blared.

Investors threw enormous bundles of cash at this device, which violated the most basic laws of physics and chemistry taught in high school. (What was shocking to me was not that a person was trying to swindle the unwary-this has been true since the dawn of time. What was surprising was that it was so easy for this inventor to fool wealthy investors because of their lack of understanding of elementary physics.) I repeated to the Journal the proverb "A fool and his money are easily parted" and P. T. Barnum's famous dictum "There's a sucker born every minute." Perhaps not surprisingly, the Financial Times, the Economist, and the Wall Street Journal have all run large feature articles on various inventors touting their perpetual motion machines.

THE THREE LAWS AND SYMMETRIES.

But all this raises a deeper question: Why do the iron laws of thermodynamics hold in the first place? It is a mystery that has intrigued scientists since the laws were first proposed. If we could answer that question, perhaps we might find loopholes in the laws, and the implications would be earth-shattering.

In graduate school I was left speechless one day when I finally learned the true origin of the conservation of energy. One of the fundamental principles of physics (discovered by mathematician Emmy Noether in 1918) is that whenever a system possesses symmetry, the result is a conservation law. If the laws of the universe remain the same over time, then the astonis.h.i.+ng result is that the system conserves energy. (Furthermore, if the laws of physics remain the same if you move in any direction, then momentum is conserved in any direction as well. And if the laws of physics remain the same under a rotation, then angular momentum is conserved.) This was staggering to me. I realized that when we a.n.a.lyze starlight from distant galaxies that are billions of light-years away, at the very edge of the visible universe, we find that the spectrum of light is identical to spectra that we can find on Earth. In the relic light that was emitted billions of years before Earth or the sun was born, we see the same unmistakable "fingerprints" of the spectrum of hydrogen, helium, carbon, neon, and so forth, that we find on the Earth today. In other words, the basic laws of physics haven't changed for billions of years, and they are constant out to the outer edges of the universe.

At a minimum, I realized, Noether's theorem means that the conservation of energy will probably last for billions of years, if not forever. As far as we know, none of the fundamental laws of physics have changed with time, and this is the reason that energy is conserved.

The implications of Noether's theorem on modern physics are profound. Whenever physicists create a new theory, whether it addresses the origin of the universe, the interactions of quarks and other subatomic particles, or antimatter, we first start with the symmetries that the system obeys. In fact, symmetries are now known to be the fundamental guiding principle in creating any new theory. In the past, symmetries were thought to be by-products of a theory-a cute but ultimately useless feature of a theory, pretty, but not essential. Today we realize that symmetries are the essential feature that defines any theory. In creating new theories, we physicists first start with symmetry, and then build the theory around it.

(Sadly, Emmy Noether, like Boltzmann before her, had to fight tooth and nail for recognition. A woman mathematician, she was denied a permanent position at leading inst.i.tutions because of her s.e.x. Noether's mentor, the great mathematician David Hilbert, was so frustrated in failing to secure a teaching appointment for Noether that he exclaimed, "What are we, a university or a bathing society?") This raises a disturbing question. If energy is conserved because the laws of physics do not change with time, then could this symmetry be broken in rare, unusual circ.u.mstances? There is still the possibility that the conservation of energy might be violated on a cosmic scale, if the symmetry of our laws is broken in exotic and unexpected places.

One way that might happen is if the laws of physics vary with time or change with distance. (In Asimov's novel The G.o.ds Themselves this symmetry was broken because there was a hole in s.p.a.ce connecting our universe with a parallel universe. The laws of physics change in the vicinity of the hole in s.p.a.ce, therefore allowing a breakdown in the laws of thermodynamics. Hence the conservation of energy could be violated if there are holes in s.p.a.ce, that is, wormholes.) Another loophole that is hotly being debated today is whether energy may spring from nothing.

ENERGY FROM THE VACUUM?.

A tantalizing question is: Is it possible to extract energy from nothing? Physicists have only recently realized that the "nothing" of the vacuum is not empty at all, but teaming with activity.

One of the proponents of this idea was the eccentric genius of the twentieth century Nikola Tesla, a worthy rival to Thomas Edison. He was also one of the proponents of zero-point energy, that is, the idea that the vacuum may possess untold quant.i.ties of energy. If true, the vacuum would be the ultimate "free lunch," capable of providing unlimited energy literally from thin air. The vacuum, instead of being considered empty and devoid of any matter, would be the ultimate storehouse of energy.

Tesla was born in a small town in what is now Serbia and arrived penniless in the United States in 1884. Soon he became an a.s.sistant to Thomas Edison, but because of his brilliance, he became a rival. In a celebrated contest, which historians dubbed "The War of the Currents," Tesla was pitted against Edison. Edison believed that he could electrify the world with his direct current (DC) motors, while Tesla was the originator of alternating current (AC) and successfully showed that his methods were far superior to Edison's and incurred significantly less power loss over distance. Today the entire planet is electrified on the basis of the patents of Tesla, not Edison.

Tesla's inventions and patents number over seven hundred and contain some of the most important milestones in modern electrical history. Historians have made a credible case that Tesla invented radio before Guglielmo Marconi (widely recognized as the inventor of radio) and was working with X-rays before their official discovery by Wilhelm Roentgen. (Both Marconi and Roentgen would later win the n.o.bel Prize for discoveries probably made by Tesla years earlier.) Tesla also believed that he could extract unlimited energy from the vacuum, a claim that unfortunately he did not prove in his notes. At first, "zero-point energy" (or the energy contained in a vacuum) seems to violate the First Law of Thermodynamics. Although zero-point energy defies the laws of Newtonian mechanics, the notion of zero-point energy has reemerged recently from a novel direction.

When scientists a.n.a.lyze the data from satellites currently orbiting the Earth, such as the WMAP satellite, they have come to the astounding conclusion that fully 73 percent of the universe is made of "dark energy," the energy of a pure vacuum. This means that the greatest reservoir of energy in the entire universe is the vacuum that separates the galaxies in the universe. (This dark energy is so colossal that it is pus.h.i.+ng the galaxies away from each other, and may eventually rip the universe apart in a Big Freeze.) Dark energy is everywhere in the universe, even in your living room and inside your body. The amount of dark energy in outer s.p.a.ce is truly astronomical, outweighing all the energy of the stars and galaxies put together. We can also calculate the amount of dark energy on the Earth, and it is quite small, too small to be used to power a perpetual motion machine. Tesla was right about dark energy but wrong about the amount of dark energy on the Earth.

Or was he?

One of the most embarra.s.sing gaps in modern physics is that no one can calculate the amount of dark energy that we can measure via our satellites. If we use the latest theory of atomic physics to calculate the amount of dark energy in the universe, we arrive at a number that is wrong by a factor of 10120! That is "one" followed by 120 zeros! This is by far the largest mismatch between theory and experiment in all of physics.

The point is that no one knows how to calculate the "energy of nothing." This is one of the most important questions in physics (because it will eventually determine the fate of the universe), but at the present time we are clueless as to how to calculate it. No theory can explain dark energy, although experimental evidence for its existence is staring us in the face.

So the vacuum does have energy, as Tesla suspected. But the amount of energy is probably too small to be used as a source of usable energy. There are vast amounts of dark energy between the galaxies, but the amount that can be found on the Earth is tiny. But the embarra.s.sing thing is that no one knows how to calculate this energy, or where it came from.

My point is that the conservation of energy arises from deep, cosmological reasons. Any violation of these laws would necessarily mean a profound s.h.i.+ft in our understanding of the evolution of the universe. And the mystery of dark energy is forcing physicists to confront this question head-on.

Because creating a true perpetual motion machine may require us to reevaluate the fundamental laws of physics on a cosmological scale, I would rank perpetual motion machines as a Cla.s.s III impossibility; that is, either they are truly impossible, or we would need to fundamentally change our understanding of fundamental physics on a cosmological scale in order to make such a machine possible. Dark energy remains one of the great unfinished chapters in modern science.

15: PRECOGNITION.

A paradox is truth standing on its head to attract attention.

-NICHOLAS FALLETTA.

Is there such a thing as precognition, or seeing the future? This ancient concept is present in every religion, going back to the oracles of the Greeks and Romans and to the prophets of the Old Testament. But in such tales, the gift of prophecy can also be a curse. In Greek mythology there is the tale of Ca.s.sandra, the daughter of the King of Troy. Because of her beauty she attracted the attention of the sun G.o.d, Apollo. To win her over Apollo granted her the ability to see the future. But Ca.s.sandra spurned the advances of Apollo. In a fit of anger, Apollo twisted his gift, so that Ca.s.sandra would be able to see the future but no one would believe her. When Ca.s.sandra warned the people of Troy of their impending doom, no one listened. She foretold the treachery of the Trojan horse, the death of Agamemnon, and even her own demise, but instead of taking heed, the people of Troy thought she was mad and locked her up.

Nostradamus, writing in the sixteenth century, and more recently Edgar Cayce have claimed that they could lift the veil of time. Although there have been many claims that their predictions have come true (for example, correctly predicting World War II, JFK's a.s.sa.s.sination, and the fall of Communism), the obscure, allegorical way in which many of these seers recorded their verses allows for a variety of contradictory interpretations. The quatrains of Nostradamus, for example, are so general that one can read almost anything into them (and people have). One quatrain reads: Earth-shaking fires from the world's center roar: Around "New City" is the Earth a-quiver Two n.o.bles long shall wage a fruitless war The nymph of springs pour forth a new, red river.

Some have claimed that this quatrain proved that Nostradamus foresaw the burning of the Twin Towers in New York on September 11,2001. Yet over the centuries scores of other interpretations have been given to this same quatrain. The images are so vague that many interpretations are possible.

Precognition is also a favorite device of playwrights who write of the impending doom of kings and the fall of empires. In Shakespeare's Macbeth, precognition is central to the theme of the play and to the ambitions of Macbeth, who encounters three witches who foresee his rise to become King of Scotland. With his murderous ambitions fired up by the witches' prophesy, he begins a b.l.o.o.d.y and grisly campaign to wipe out his enemies, including killing the innocent wife and children of his rival Macduff.

After committing a series of hideous deeds to seize the crown, Macbeth learns from the witches that he cannot be defeated in battle or "vanquish'd be until great Birnam Wood to high (Dunsinane Hills) shall come against him," and that "none of woman born shall harm Macbeth." Macbeth takes comfort in this prophecy, since a forest cannot move, and all men are born of women. But the Great Birnam forest does move, as the troops of Macduff camouflaging themselves beneath twigs from the Great Birnam forest, advance on Macbeth, and Macduff himself was born via cesarean.

Although prophecies from the past have so many alternative interpretations, and hence are impossible to test, one set of prophecies is easy to a.n.a.lyze: predictions of the precise date of the end of the Earth-Doomsday. Ever since the last chapter of the Bible, Revelations, laid out in graphic detail the final days of the Earth, when chaos and destruction will accompany the arrival of the Antichrist and the final Second Coming of Christ, fundamentalists have tried to predict the precise date of the End of Days.

One of the most celebrated of all Doomsday predictions was made by astrologers who predicted a great flood that would end the world on February 20, 1524, based on the conjunction of all the planets in the heavens: Mercury, Venus, Mars, Jupiter, and Saturn. Ma.s.s panic swept across Europe. In England, twenty thousand people fled their homes in desperation. A fortress stocked with food and water to last two months was built around St. Bartholomew's Church. Across Germany and France, people furiously set out to build large arks to ride out the flood. Count Von Iggleheim even built a huge, three-story ark in preparation for this momentous event. But when the date finally arrived, there was only a slight rain. The mood of the crowd suddenly swung from fear into anger. People who had sold all their belongings and turned their lives upside down felt betrayed. Angry mobs began to run amok. The count was stoned to death, and hundreds were killed when the mob stampeded.

Christians aren't the only ones who feel the lure of prophecy. In 1648 Sabbatai Zevi, the son of a wealthy Jew in Smyrna, declared himself to be the Messiah and predicted that the world would end in 1666. Handsome, charismatic, and well versed in the mystical texts of the Kabbalah, he quickly a.s.sembled a group of fiercely loyal followers, who spread the news across Europe. In the spring of 1666 Jews from as far away as France, Holland, Germany, and Hungary began to pack their bags and heed the call of their Messiah. But later that year Zevi was arrested by the grand vizier in Constantinople and thrown in prison in chains. Facing a possible death sentence, he dramatically cast off his Jewish clothes, adopted a Turkish turban, and converted to Islam. Tens of thousands of his devout followers left the cult in utter disillusionment.

The prophecies of seers still resonate even today, influencing the lives of tens of millions of people worldwide. In the United States, William Miller declared that Doomsday would arrive on April 3, 1843. As news of his prophecy spread thoughout the United States, a spectacular meteor shower by chance lit up the night sky in 1833, one of the largest of its kind, further enhancing the influence of Miller's prophecy.

Tens of thousands of devout followers, called Millerites, awaited the coming of Armageddon. When 1843 came and went without the arrival of the End of Days, the Millerite movement split into several large groups. Because of the huge following ama.s.sed by the Millerites, each of these splinter groups would have a major impact on religion even today. One large piece of the Millerite movement regrouped in 1863 and changed their name to the Seventh-Day Adventist Church, which today has about 14 million baptized members. Central to their belief is the imminent Second Coming of Christ.

Another splinter group of Millerites later drifted toward the work of Charles Taze Russell, who pushed back the date of Doomsday to 1874. When that date also pa.s.sed, he revised his prediction, based on a.n.a.lyses of the Great Pyramids of Egypt, this time to 1914. This group would later be called Jehovah's Witnesses, with a members.h.i.+p of over 6 million.

Other segments of the Millerite movement, however, continued to make predictions, hence precipitating further splits each time a prediction failed. One small splinter group of Millerites was called the Branch Davidians; they broke off from the Seventh-Day Adventists in the 1930s. They had a small commune in Waco, Texas, which fell under the charismatic influence of a young preacher named David Koresh, who spoke hypnotically of the end of the world. That group met a fiery end in their tragic encounter with the FBI in 1993, when a raging inferno consumed the compound, incinerating 76 members, including 27 children, and also Koresh.

CAN WE SEE THE FUTURE?.

Can rigorous scientific tests prove that some individuals can see the future? In Chapter 12 we saw that time travel might be consistent with the laws of physics, but for an advanced, Type III civilization. But is precognition possible on Earth today?

Elaborate tests conducted at the Rhine Center seem to suggest that some people can see the future; that is, they can identify cards before they are unveiled. But repeated experiments have shown that the effect is very small, and often disappears when others try to duplicate the results.

In fact, precognition is difficult to reconcile with modern physics, because it violates causality, the law of cause and effect. Effects occur after the cause, not vice versa. All the laws of physics that have been found so far have causality built into them. A violation of causality would signal a major collapse of the foundations of physics. Newtonian mechanics is firmly based on causality. Newton's laws are so all-embracing that if you know the location and position of all the molecules in the universe, you can calculate the future motion of these atoms. Thus the future is calculable. In principle, Newtonian mechanics states that if you had a large enough computer, you could compute all future events. According to Newton, the universe is like a gigantic clock, wound up by G.o.d at the beginning of time, and ticking ever since according to His laws. There is no room for precognition in Newton's theory.

BACKWARD IN TIME.

When we discuss Maxwell's theory, however, the scenario becomes much more complicated. When we solve Maxwell's equations for light, we find not one but two solutions: a "r.e.t.a.r.ded" wave, which represents the standard motion of light from one point to another; but also an "advanced" wave, where the light beam goes backward in time. This advanced solution comes from the future and arrives in the past!

For a hundred years when engineers have encountered this "advanced" solution that goes backward in time they have simply dismissed it as a mathematical curiosity. Since the r.e.t.a.r.ded waves so accurately predicted the behavior of radio, microwaves, TV, radar, and X-rays, they simply threw the advanced solution out the window. The r.e.t.a.r.ded waves were so spectacularly beautiful and successful that engineers simply ignored the ugly twin. Why tamper with success?

But for physicists, the advanced wave has been a nagging problem for the past century. Since Maxwell's equations are among the pillars of the modern age, any solution of these equations has to be taken very seriously, even if it entails accepting waves from the future. It seemed that it was impossible to totally ignore the advanced waves from the future. Why would nature, at this most fundamental level, give us such a bizarre solution? Was this a cruel joke, or was there a more profound meaning?

Mystics began to take an interest in these advanced waves, speculating that they would appear as messages from the future. Perhaps if we could somehow harness these waves, we might be able to send messages back to the past, and hence alert previous generations of events to come. We could, for example, send a message back to our grandparents in the year 1929, warning them to sell all their stocks before the Great Crash. Such advanced waves would not allow us personally to visit the past, as in time travel, but they would enable us to send letters and messages into the past to alert people of key events that would not yet have occurred.

These advanced waves were a mystery until they were studied by Richard Feynman, who was intrigued by the idea of going backward in time. After working on the Manhattan Project, which built the first atomic bomb, Feynman left Los Alamos and went to Princeton University to work under John Wheeler. a.n.a.lyzing Dirac's original work on the electron, Feynman found something very strange. If he simply reversed the direction of time in Dirac's equation, the equation remained the same if he also reversed the electron charge. In other words, an electron going backward in time was the same as an antielectron going forward in time! Normally, a mature physicist might dismiss this interpretation, calling it just a trick, a mathematical sleight-of-hand with no meaning. Going backward in time did not seem to make any sense, yet Dirac's equations were clear on this point. In other words, Feynman had found the reason that nature allowed these backward-in-time solutions: they represented the motion of antimatter. If he had been an older physicist, Feynman might have thrown this solution out the window. But being a lowly graduate student, he decided to pursue his curiosity further.

As he continued to delve into this conundrum the young Feynman noticed something even stranger. Normally if an electron and an antielectron collide, they annihilate one another and create a gamma ray. He drew this on a sheet of paper: two objects b.u.mping into each other, turning into a burst of energy.

But then if you reversed the charge of the antielectron, it became an ordinary electron going backward in time. You could then rewrite the same diagram with the arrow of time reversed. It now appeared as if the electron went forward in time, then suddenly decided to reverse direction. The electron did a U-turn in time and was now going backward in time, releasing a burst of energy in the process. In other words, it's the same electron. The electron-antielectron annihilation process was just the same electron deciding to go backward in time!