Part 1 (1/2)

Physics of the Impossible

Kaku, Michio

PREFACE

If at first an idea does not sound absurd, then there is no hope for it

-ALBERT EINSTEIN

One day, would it be possible to walk through walls? To build starshi+ps that can travel faster than the speed of light? To read other people's minds? To become invisible? To move objects with the power of our h outer space?

Since I was a child, I've always been fascinated by these questions Likeup, I was uns, force fields, parallel universes, and the like Magic, fantasy, science fiction were all a gigantic playground forlove affair with the i the old Flash Gordon reruns on TV Every Saturday, I was glued to the TV set,at the adventures of Flash, Dr Zarkov, and Dale Arden and their dazzling array of futuristic technology: the rocket shi+ps, invisibility shi+elds, ray guns, and cities in the sky I never ram opened up an entirely neorld forto an alien planet and exploring its strange terrain Being pulled into the orbit of these fantastic inventions I knew that my own destiny was somehorapped up with the marvels of the science that the show prohly accoinally becah exposure to science fiction The great astronomer Edwin Hubble was fascinated by the works of Jules Verne As a result of reading Verne's work, Hubble abandoned a pro his father's wishes, set off on a career in science He eventually becaan, noted astronoination set afire by reading Edgar Rice Burroughs's John Carter of Mars novels Like John Carter, he drea the sands of Mars

I was just a child the day when Albert Einstein died, but I re about his life, and death, in hushed tones The next day I saw in the newspapers a picture of his desk, with the unfinished reatest, unfinished work I asked reatest scientist of our time could not finish it? The article claimed that Einstein had an impossible dream, a problem so difficult that it was not possible for a mortal to finish it It took rand, unifying ”theory of everything” His dream-which consumed the last three decades of his life-helped ination I wanted, in some small way, to be part of the effort to complete Einstein's work, to unify the laws of physics into a single theory

As I grew older I began to realize that although Flash Gordon was the hero and always got the girl, it was the scientist who actually made the TV series work Without Dr Zarkov, there would be no rocket shi+p, no trips to Mongo, no saving Earth Heroics aside, without science there is no science fiction

I came to realize that these tales were sihts of the i away such fantasy In real life, I was told, one had to abandon the impossible and embrace the practical

However, I concluded that if I was to continue h the realround in advanced physics, I would be forever speculating about futuristic technologies without understanding whether or not they were possible I realized I needed to immerse myself in advanced mathematics and learn theoretical physics So that is what I did

In high school for my science fair project I assee I went to the Westinghouse coathered 400 pounds of scrap transformer steel Over Christh school football field Eventually I built a 23-million-electron-volt betatron particle accelerator, which consuenerated a netic field The goal was to generate a beah to create antimatter

My science fair project took me to the National Science Fair and eventually fulfilleda scholarshi+p to Harvard, where I could finally pursuea theoretical physicist and follow in the footsteps of my role model, Albert Einstein

Today I receive e-the limits of the laws of physics

THE ”IMPOSSIBLE” IS RELATIVE

As a physicist, I have learned that the ”i up, I re up to theout the coastlines of South America and Africa Wasn't it an odd coincidence, she said, that the two coastlines fit together, alsaw puzzle? Some scientists, she said, speculated that perhaps they were once part of the same, vast continent But that was silly No force could possibly push two gigantic continents apart Such thinking was impossible, she concluded

Later that year we studied the dinosaurs Wasn't it strange, our teacher told us, that the dinosaurs dominated the Earth for millions of years, and then one day they all vanished? No one knehy they had all died off Soht that maybe a meteor from space had killed them, but that was impossible, more in the realh plate tectonics the continents do anticsix miles across most likely did obliterate the dinosaurs and much of life on Earth In ly iain So is it iht one day be able to teleport ourselves from one place to another, or build a spaceshi+p that will one day take us light-years away to the stars?

Normally such feats would be considered iht they become possible within a few centuries? Or in ten thousand years, when our technology is more advanced? Or in a million years? To put it another way, if ere to somehow encounter a civilization a million years y appear to be ”ic” to us? That, at its heart, is one of the central questions running through this book; just because so is ”impossible” today, will it remain impossible centuries or millions of years into the future?

Given the remarkable advances in science in the past century, especially the creation of the quantuive rough estiiesof eventheory, even concepts bordering on science fiction, such as ti re-evaluated by physicists Think back 150 years to those technological advances that were declared ”impossible” by scientists at the time and that have now become part of our everyday lives Jules Verne wrote a novel in 1863, Paris in the Twentieth Century, which was locked away and forgotten for over a century until it was accidentally discovered by his great-grandson and published for the first tiht look like in the year 1960 His novel was filled with technology that was clearly considered i fax lass skyscrapers, gas-powered autoly, Verne could ly accurate predictions because he was i the brains of scientists around him A deep appreciation for the funda predictions

Sadly, soreatest scientists of the nineteenth century took the opposite position and declared any nuies to be hopelessly impossible Lord Kelvin, perhaps the most prominent physicist of the Victorian era (he is buried next to Isaac Newton in Westminster Abbey), declared that ”heavier than air” devices such as the airplane were iht X-rays were a hoax and that radio had no future Lord Rutherford, who discovered the nucleus of the ato an ato it to ”moonshi+ne” Chemists of the nineteenth century declared the search for the philosopher's stone, a fabled substance that can turn lead into gold, a scientific dead end Nineteenth-century chemistry was based on the fundamental immutability of the elements, like lead Yet with today's atoold Think how fantastic today's televisions, computers, and Internet would have seemed at the turn of the twentieth century

More recently, black holes were once considered to be science fiction Einstein himself wrote a paper in 1939 that ”proved” that black holes could never form Yet today the Hubble space Telescope and the Chandra X-ray telescope have revealed thousands of black holes in space

The reason that these technologies were deemed ”impossibilities” is that the basic laws of physics and science were not known in the nineteenth century and the early part of the twentieth Given the huge gaps in the understanding of science at the time, especially at the atomic level, it's no wonder such advances were considered impossible

STUDYING THE IMPOSSIBLE

Ironically, the serious study of the impossible has frequently opened up rich and entirely unexpected domains of science For exa and futile search for a ”perpetual motion machine” led physicists to conclude that such athey and the three laws of thermodynamics Thus the futile search to build perpetual motion machines helped to open up the entirely new field of therine, the e, and modern industrial society

At the end of the nineteenth century, scientists decided that it was ”impossible” for the Earth to be billions of years old Lord Kelvin declared flatly that a molten Earth would cool down in 20 to 40 ists and Darwinian biologists who claiht be billions of years old The impossible was finally proven to be possible with the discovery of the nuclear force by Mada how the center of the Earth, heated by radioactive decay, could indeed be kept nore the impossible at our peril In the 1920s and 1930s Robert Goddard, the founder of modern rocketry, was the subject of intense criticisht that rockets could never travel in outer space They sarcastically called his pursuit Goddard's Folly In 1921 the editors of the New York Tiainst Dr Goddard's work: ”Professor Goddard does not know the relation between action and reaction and the need to have soainst which to react He seeh schools” Rockets were impossible, the editors huffed, because there was no air to push against in outer space Sadly, one head of state did understand the implications of Goddard's ”i World War II, Gere of impossibly advanced V-2 rockets rained death and destruction on London, al the ied the course of world history In the 1930s it idely believed, even by Einstein, that an atomic bomb was ”impossible” Physicists knew that there was a trey locked deep inside the ato to Einstein's equation E = nificant to consider But ato the 1914 H G Wells novel, The World Set Free, in which Wells predicted the development of the atomic bomb In the book he stated that the secret of the atomic bomb would be solved by a physicist in 1933 By chance Szilard stumbled upon this book in 1932 Spurred on by the novel, in 1933, precisely as predicted by Wells so the power of a single atole uraniunified by many trillions Szilard then set into otiations between Einstein and President Franklin Roosevelt that would lead to the Manhattan Project, which built the atoain we see that the study of the i the boundaries of physics and che scientists to redefine what they mean by ”impossible” As Sir Williae have become the absurdities of the next, and the foolishness of yesterday has become the wisdom of tomorrow”

Many physicists subscribe to the famous dictu, ”Anything that is not forbidden, is mandatory!” In physics we find evidence of this all the ti a new phenomenon, we eventually find that it exists (This has happened several ti the limits of what is forbidden, physicists have often unexpectedly discovered nes of physics) A corollary to T H White's state that is not iist Stephen Hawking tried to prove that ti a ne of physics that would forbid it, which he called the ”chronology protection conjecture” Unfortunately, after many years of hard work he was unable to prove this principle In fact, to the contrary, physicists have now demonstrated that a law that prevents time travel is beyond our present-day mathe the existence of time machines, physicists have had to take their possibility very seriously

The purpose of this book is to consider what technologies are considered ”iht well become commonplace decades to centuries down the road

Already one ”i to be possible: the notion of teleportation (at least at the level of atoo physicists would have said that sending or bea an object from one point to another violated the laws of quantuinal Star Trek television series, in fact, were so stung by the criticis compensators” to explain their teleporters in order to address this flaw Today, because of a recent breakthrough, physicists can teleport atoms across a room or photons under the Danube River

PREDICTING THE FUTURE

It is always a bit dangerous to make predictions, especially ones set centuries to thousands of years in the future The physicist Niels Bohr was fond of saying, ”Prediction is very hard to do Especially about the future” But there is a fundamental difference between the time of Jules Verne and the present Today the fundamental laws of physics are basically understood Physicists today understand the basic laws extending over a staggering forty-three orders of nitude, fro universe As a result, physicists can state, with reasonable confidence, what the broad outlines of future technology ht look like, and better differentiate between those technologies that are merely improbable and those that are truly is that are ”iories

The first are what I call Class I iies that are impossible today but that do not violate the knos of physics So they ht be possible in this century, or perhaps the next, in ines, certain forms of telepathy, psychokinesis, and invisibility

The second category is what I teries that sit at the very edge of our understanding of the physical world If they are possible at all, they ht be realized on a scale of millennia to millions of years in the future They include time machines, the possibility of hyperspace travel, and travel through worory is what I call Class III iies that violate the knos of physics Surprisingly, there are very few such iies If they do turn out to be possible, they would represent a funda of physics

This classification is significant, I feel, because so ies in science fiction are dis totally impossible, hat they actually mean is that they are impossible for a primitive civilization like ours Alien visitations, for example, are usually considered impossible because the distances between the stars are so vast While interstellar travel for our civilization is clearly impossible, it may be possible for a civilization centuries to thousands or millions of years ahead of ours So it is iies that are impossible for our current civilization are not necessarily impossible for other types of civilizations Statements about what is possible and iies that are an once wrote, ”What does it mean for a civilization to be a million years old? We have had radio telescopes and spaceshi+ps for a few decades; our technical civilization is a few hundred years oldan advanced civilization millions of years old is as much beyond us as we are beyond a bush baby or a macaque”

Into co” Personally, I find it quite exhilarating to work on a ”final theory” that may ultimately answer some of the most difficult ”impossible” questions in science today, such as whether time travel is possible, what lies at the center of a black hole, or what happened before the big bang I still daydrea love affair with the impossible, and wonder when and if soht enter the ranks of the everyday

ACKNOWLEDGMENTS