Until recently the stuff of sci-fi fiction and Star Trek reruns, teleportation has become a reality-for subatomic particles at least. In this eye-opening book, science author David Darling follows the remarkable evolution of teleportation, visiting the key labs that have cradled this cutting-edge science and relating the all-too-human stories behind its birth. He ties in the fast emerging fields of cryptography and quantum computing, tackles some thorny philosophical questions (for instance, can a soul be teleported?), and asks when and how humans may be able to "beam up."
Until recently the stuff of sci-fi fiction and Star Trek reruns, teleportation has become a reality-for subatomic particles at least. In this eye-opening book, science author David Darling follows the remarkable evolution of teleportation, visiting the key labs that have cradled this cutting-edge science and relating the all-too-human stories behind its birth. He ties in the fast emerging fields of cryptography and quantum computing, tackles some thorny philosophical questions (for instance, can a soul be teleported?), and asks when and how humans may be able to "beam up."
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Overview
Until recently the stuff of sci-fi fiction and Star Trek reruns, teleportation has become a reality-for subatomic particles at least. In this eye-opening book, science author David Darling follows the remarkable evolution of teleportation, visiting the key labs that have cradled this cutting-edge science and relating the all-too-human stories behind its birth. He ties in the fast emerging fields of cryptography and quantum computing, tackles some thorny philosophical questions (for instance, can a soul be teleported?), and asks when and how humans may be able to "beam up."
Product Details
| ISBN-13: | 9780470248720 |
|---|---|
| Publisher: | Trade Paper Press |
| Publication date: | 08/17/2007 |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 288 |
| File size: | 441 KB |
About the Author
Read an Excerpt
Teleportation
By David Darling
John Wiley & Sons
ISBN: 0-471-47095-3Chapter One
Light Readings
It was a low-key affair: no television cameras or reporters were on hand. No audience of millions was hanging breathlessly on the mission's success. In a small, darkened room at the University of Innsbruck in 1997, on a lab bench strewn with cables and electro-optical gear, scientists destroyed a few bits of light in one place and made perfect replicas about a meter away. True, it lacked the drama and visceral appeal of Armstrong and Aldrin's exploits on the moon. But in the long run it was no less important. The first teleportation in history had just taken place.
Nothing is more familiar than light. It's the moon reflected on a calm ocean, a sparkling diamond, a rainbow, a glowing ember. We take it for granted because it's all around us. But behind everyday appearances lies the question of what light really is-what it's made of, how it behaves, and how on Earth it's possible to make it vanish in one place and then reappear, an instant later, somewhere else. To understand the science of teleportation we first have to come to grips with the nature of light.
In ancient Greek mythology, the goddess Aphrodite fashioned the human eye out of the four elements-earth, air, fire, and water-then lit a flame inside the eye to shine out and make sight possible. According to this explanation, we can't see in the dark because rays from the eyes must interact with rays from a sourcesuch as the sun. So taught Empedocles, in the fifth century B.C., and, for most Europeans, it was a theory good enough to stand for the next two thousand years.
Other ancients, though, came closer to the modern view. The Roman poet and philosopher Lucretius was far ahead of his time when, in 55 B.C., he wrote: "The light and heat of the sun; these are composed of minute atoms which, when they are pushed off, lose no time in shooting right across the interspace of air in the direction imparted by the push." Earlier, Euclid had described the laws of reflection and argued that light travels in straight lines. In about A.D. 140, Ptolemy found, from careful measurements of the positions of stars, that light is refracted, or bent, as it passes through the atmosphere.
Most advanced of all, before the scientists of the Renaissance, was Ibn al-Haytham, who lived around the turn of the tenth century in what is now Iraq. He rejected the eye-beam idea, understood that light must have a large but finite velocity, and realized that refraction is caused by the velocity being different in different substances. Those facts had to be relearned in the West several centuries later. But when they had been, a great debate sprang up around light's basic nature that set the stage for the startling revelations of more recent times.
By the seventeenth century, two theories competed to explain the underlying essence of light. Isaac Newton insisted that light is made of particles or, to use the term then in vogue, corpuscles (meaning "little bodies"). His contemporary, the Dutch physicist Christiaan Huygens, championed the idea that light consists of waves.
Newton's corpuscular theory fit in well with some of his other groundbreaking work on the way objects move. After all, light is seen to travel in straight lines, and how it is reflected by a mirror seems similar to how a ball bounces off a wall. Newton revolutionized optics: he split apart white light with prisms and showed that it's a mixture of all the colors of the rainbow, and he built the first reflecting telescope. But all his thoughts in this field were guided by his belief that light is a stream of little particles.
Huygens took the rival view that light is really made of waves, like those that ripple out when a stone is tossed into a lake. The medium through which light waves travel, Huygens supposed, is an invisible substance called the luminiferous ether-an idea he inherited from his old tutor Rene Descartes.
Both corpuscular and wave theories could explain perfectly well the reflection and refraction of light. It's true Newton and Huygens differed in their predictions about the way the speed of light changes as light goes from a less dense medium, such as air, to a more dense one, such as glass; Newton said it should go up, and Huygens believed it should go down. As there was no way of measuring this speed change at the time, however, it couldn't be used as an experimental test. One observation, though, did tilt the scales of seventeenth-century opinion. When light from a faraway source, such as the sun, passes a sharp edge, such as the wall of a house, it casts a sharp-edged shadow. That's exactly what you'd expect of streams of particles, traveling on dead straight courses. On the other hand, if light were made of waves it ought to diffract, or spread around corners, just as ocean waves wash around the sides of a harbor wall, and cast a shadow that was fuzzy-edged. The observation of clean-edged shadows, together with Newton's huge stature in science, guaranteed almost unanimous support for the corpuscular view. Then came a sea change. Early in the nineteenth century, the balance of opinion started to shift emphatically the other way, and the wave picture of light moved to center stage.
The instigator of this shift was Thomas Young, an English physician, physicist, and linguist extraordinaire. The first of ten children of Quaker parents, Young was a precocious youngster of fiercely independent mind who learned to read at the age of two, knew Latin as a six-year-old, and was fluent in thirteen languages while still a teenager. Later he played a key role in unraveling the mysteries of Egyptian hieroglyphics through his deciphering of several cartouches-oval figures containing royal names-on the Rosetta stone. But his greatest claim to fame lies with his work on optics.
Having studied medicine in London, Edinburgh, Gottingen, and Cambridge, Young bought a house in London with money left him by a wealthy uncle and set up practice there. From 1811 to the time of his death, he served as a physician at St. George's Hospital. His main medical interest, though, wasn't in treating patients but in doing research. Human vision and the mechanism of the eye held a special fascination for him.
As early as 1790 or thereabouts, barely out of school, Young had hatched the original theory of how color vision comes about, building on work by Newton. Through his experiments with prisms back in 1672, Newton had shown that, rather surprisingly, ordinary white light is a thorough blend of all the rainbow colors from red to violet. Objects have a particular hue, Newton realized, because they reflect some colors more than others. A red apple is red because it reflects rays from the red end of the spectrum and absorbs rays from the blue end. A blueberry, on the other hand, reflects strongly at the blue end of the spectrum and absorbs the red. Thinking about Newton's discovery, Young concluded that the retina at the back of the eye couldn't possibly have a different receptor for each type of light, because there was a continuum of colors from red to violet. There was no way there could be such a vast number of specific receptors. Instead, he proposed that colors were perceived by way of a simple three-color code. As artists knew well, any color of the spectrum (except white) could be matched by judicious blending of just three colors of paint. Young suggested that this three-color code wasn't an intrinsic property of light, but arose from the combined activity of three different "particles" in the retina, each sensitive to different parts of the spectrum. In fact, we now know that color vision depends on the interaction of three types of cone cells: one especially sensitive to red light, another to green light, and a third to blue light. Considering that Young set out his three-color theory before cone cells had been discovered, he came remarkably close to the truth.
While still a medical student at Emmanuel College in Cambridge, Young also discovered how the lens of the eye changes shape to focus on objects at different distances. In 1801, just after his move to London, he showed that astigmatism results from an abnormally shaped cornea. At the age of only twenty-eight, Young was already professor of natural philosophy at the Royal Institution and lecturing on just about everything under and above the sun: acoustics, optics, gravitation, astronomy, tides, electricity, energy (he was the first to give the word energy its scientific significance), climate, animal life, vegetation, cohesion and capillary attraction of liquids, and the hydrodynamics of reservoirs, canals, and harbors. His epitaph in Westminster Abbey says it all: "a man alike eminent in almost every department of human learning."
It was Young's work on optics that eventually made him famous-and a heretic in his own land. Having pioneered physiological optics it was only a short step to considering the fundamental essence of light, and in that fateful year of 1801, Young turned his mind to light's basic nature. His interest in this question was piqued by some work he'd done in the mid-1790s on the transmission of sound, which he came to believe was analogous to light. Sound was made of waves. Young suspected that light was, too. So in 1802, he devised an experiment to put this theory to the test.
If light were made of waves, then from a very narrow opening in its path it should head out as a series of concentric, circular ripples. To grasp this idea, imagine a long rectangular trough of water. Halfway down the trough is a barrier with a small hole in it. Straight, parallel waves, like the lines of waves marching toward a shore before they break, are created by moving a plank of wood back and forth at one end of the trough. When a wave reaches the barrier it is stopped dead in its tracks-except for at the small hole. This opening serves as a new source of waves, but of expanding circular waves, as if a pebble had been dropped into the water at that point. On the side of the tank beyond the barrier, the secondary waves fan out, circles within circles. Now suppose there are two little holes in the barrier across the water tank. Both act as sources of circular waves. What's more, these waves are exactly in step-in phase, to use the scientific description-because they've come from the same set of waves that arrived at the barrier. As the circular waves spread out from the two holes, they run into one another and interact. They interfere. Where two crests or two troughs coincide, they combine to give a crest or trough of double the height. Where a crest meets a trough, the two cancel out to leave an undisturbed spot. Drop two pebbles of equal size close together in a pond and you'll see an instant demonstration. The result is an interference pattern.
Thomas Young carried out the equivalent of this waterwave interference experiment using light. In a darkened room, he shone light upon a barrier in which there were two narrow, parallel slits, within a fraction of an inch of each other. Then he looked at the outcome on a white screen set farther back. If light were made of particles, as Newton claimed, the only thing showing on the screen ought to be two bright parallel lines where the light particles had shot straight through. On the other hand, if light, like water, were wavelike, the secondary light waves spreading out from the two slits should create a pattern of alternate dark and light bands, where the light from the two sources respectively canceled out and amplified. Young's result was literally black and white: a series of interference bands. His double-slit experiment argued powerfully in favor of the wave model of light.
Flushed with success, Young used his proof of the wave character of light to explain the beautiful, shifting colors of thin films, such as those of soap bubbles. Relating color to wavelength, he also calculated the approximate wavelengths of the seven colors of the rainbow recognized by Newton. In 1817, he proposed that light waves were transverse, in other words that they vibrate at right angles to the direction in which they travel. Up to that time, supporters of the wave theory of light had assumed that, like sound waves, light waves were longitudinal, vibrating along their direction of motion. Using his novel idea of transverse waves, Young was able to explain polarization-a phenomenon that looms large in our story of teleportation-as the alignment of light waves so that they vibrate in the same plane.
For these breakthroughs, Young ought to have been hailed as a wunderkind, a youthful genius who set physics on its head. But he'd had the audacity to challenge the authority of Newton in the great man's own domain, and that was the scientific equivalent of hari-kari. A savage, anonymous review of Young's work in 1803 in the Edinburgh Review (now known to have been by Lord Henry Brougham, a big fan of the corpuscular theory) cast Young into scientific limbo for at least a decade. Newton had been dead eighty years when Young officially published his findings on interference in 1807. But the godlike status of the great man in Britain meant that Young's compelling results were pretty much ignored by his compatriots.
Instead it fell to a Frenchman, Augustin Fresnel, to persuade the world a few years later, through a series of demonstrations that were more comprehensive than those of Young, that light really was a series of waves and not a movement of minuscule particles. By the mid-nineteenth century, when Leon Foucault, another French physicist, showed that, contrary to the expectations of Newton's corpuscular theory, light traveled more slowly in water than in air, the wave picture of light was firmly established. All that remained was to clear up some details. If light consisted of waves, what was the nature of these waves? What exactly was waving?
In the 1860s, the final pieces of the puzzle of light seemed to fall into place thanks to the work of the Scottish theoretical physicist James Clerk Maxwell. What Maxwell found was a set of relationships-four simple-looking formulas (though not so simple in fact!) known ever since as Maxwell's equations-that bind electricity and magnetism inextricably together. These equations explained, for example, all the results of the pivotal experiments on electric currents and magnetic fields that Michael Faraday had carried out in the 1830s at the Royal Institution in London. Maxwell's equations assume that around magnets, electric charges, and currents there exist regions of influence known as fields. Crucially, the equations show that it's meaningless to talk about these fields on their own. Wherever there's an electric field, there's always an accompanying magnetic field at right angles to it, and vice versa. The two can't exist apart, and together they produce a marriage called an electromagnetic field.
As Maxwell's equations make clear, change the electric field and the magnetic field responds by changing as well. The disturbance to the magnetic field then causes a further shift in the electric field, and so on, back and forth, action and reaction. Maxwell was aware of the implication of this two-way feedback. It meant that any fluctuation in an electric or magnetic field gives rise to electromagnetic waves. The frequency of these waves equals the rate at which the electromagnetic field waxes and wanes. Using his formulas, Maxwell could even figure out the speed at which electromagnetic waves should travel: 300,000 kilometers per second. But this value was already very familiar in science. It was equal to the speed of light, which by the mid-nineteenth century was known quite accurately, and there was no way Maxwell was going to take that as mere coincidence. In 1867, he proposed that light waves were none other than electromagnetic waves. "We can scarcely avoid the conclusion," he wrote, "that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena."
(Continues...)
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Table of Contents
Acknowledgments.Prologue.
Introduction: A Brief History of Beaming Up.
1. Light Readings.
2. Ghosts in the Material World.
3. The Mysterious Link.
4. Dataverse.
5. Secret Communications.
6. A Miracle in Montreal.
7. Small Steps and Quantum Leaps.
8. A Computer without Bounds.
9. Atoms, Molecules, Microbes . . ..
10. Far-fetched and Far-reaching.
Epilogue.
Chronology.
References.
Bibliography.
Index.