Physics of the Impossible by Michio Kaku
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 Class 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 classic novel The Gods 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 space 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 quantities 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, entitled “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. Analyses of the bones of our ancestors show evidence of enormous wear and tear, caused by the crushing 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 class 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 passengers 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 appetite 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 passed over the stationary magnet, it was supposed to be attracted then repelled by the larger magnet, thereby pushing 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 analyzed 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 be
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 title “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 basement 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 circumstances, 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 naïve 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 Cox 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 Cox’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 entity. 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 assumption: that gases were made of tiny atoms that, like billiard balls, 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 balls, 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 assumption 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
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.