A century later, Einstein's first ideas still hold power

It's rare that a person gets a chance to overturn humanity's conception of the universe.

But with five scientific papers submitted in 1905, Albert Einstein managed to do that three times: proving the existence of atoms, uncloaking the bizarre realm of quantum mechanics and overturning views of space and time.

Einstein overhauled much of physics at age 26 during a seven-year stint as a Swiss patent clerk, newly married to his first wife and with a 1-year-old son. This year, physicists, authors, cooperative computing projects and even choreographers are commemorating his achievement.

Einstein is best known to the general public for his theory of relativity, the opening salvo of which came in a paper submitted in June 1905. That theory ultimately created a new conception of space, time and gravity. But the Nobel Prize came for his first work of 1905, which helped lay the foundation for quantum physics by suggesting that light behaves both like a wave and as a particle.

"Relativity stretched our notions of space and time, but we still had space and time. Quantum physics destroys our everyday notions," said Richard Wolfson, a professor at Middlebury College in Vermont, in a lecture marking the 100th anniversary of Einstein's annus mirabilis.

And the shock waves spread widely: Decades later, the quantum revolution Einstein helped begin has become a fact of life in microprocessor design.

Einstein's papers that year are neatly packaged resolutions to the physics problems of the day. He launched them without the support--or hindrances--associated with being a typical young university researcher.

"It's unlikely he could have come up with relativity and quantum theory as a junior lecturer in a well-established physics department, where such ideas would probably have been suppressed as cranky coming from a man with no reputation," said Andrew Robinson, a scholar at Eton College and the author and editor of "Einstein: A Hundred Years of Relativity," to be published by Harry N. Abrams later this year.

To a certain extent, Einstein was in the right field at the right time. Experiments to test new theories were more affordable, and the field of physics was young enough to accommodate generalists such as Einstein.

"The outstanding problems in physics now are in some respects harder than the outstanding problems in physics 100 years ago," said Rice University physics professor Doug Natelson. That doesn't mean Einstein had it easy, though. If Einstein hadn't existed, he said, "I doubt it would have been one individual who would have figured out all these things in such a short space of time."

Quantum physics

Einstein's first paper, submitted in March, concerned quantum physics, the peculiar realm of the ultra-tiny in which certainties are replaced by fuzzy clouds of probability. Max Planck started the quantum physics ball rolling in 1900, but Einstein gave it major impetus when he showed that 19th-century physicists' view of light as electromagnetic wave was incomplete.

The word "quantum" refers to discrete packets of light--particles now called photons. Einstein's work helped show that light behaved both as particle and a wave.

Light's wavelike nature could be seen in phenomena such as interference patterns that also appear with waves in water. For example, with both light and water, peaks of two waves can combine into a taller peak, or a trough of one wave can cancel out the peak of another.

But some phenomena don't take well to the wave description. One was the photoelectric effect, in which light shining on metal causes it to emit electrons. Einstein's first 1905 paper relied on the quantum description of light to explain how an increase in the light intensity caused more electrons to be emitted--but not higher-energy electrons, as the wave theory predicts.

"This was revolutionary. Neither classic mechanics nor classical electromagnetic theory could survive in the face of quantum phenomena," said John Stachel, editor of "Einstein's Miraculous Year: Five Papers That Changed the Face of Physics."

Quantum physics didn't even sit well with Einstein himself. "No longer did tiny particles have a definite position and speed...Einstein was horrified by this random, unpredictable element in the basic laws and never fully accepted quantum mechanics," said Stephen Hawking, a cosmologist at the University of Cambridge in England, in an essay in Robinson's book.

Molecules and atoms

The next two papers were easier for the physics community to swallow. They validated the idea that matter was composed of atoms and of groups of atoms called molecules.

Though most scientists accepted the concept, there were significant holdouts. "At that time, there were people who doubted the existence of molecules," Stachel said.

The first of these papers, a doctoral thesis submitted in April, was Einstein's prediction that the size of molecules could be gauged by the effects of dissolving sugar in a liquid. Einstein argued that "the effect of the dissolution of sugar molecules would change the viscosity of fluid; you can measure the viscosity, and from that estimate the size of the molecules," Stachel said. His prediction proved to be not far from reality.

Second was a description of the mechanism underlying Brownian motion--a particle's small random movements named after botanist named Robert Brown who observed pollen grains jiggling in water. Einstein derived a theory that predicted how far a particle will move over time, given such buffeting--a theory that was confirmed a few years later and which demonstrated that properties such as temperature and pressure were reflections of the average behavior of huge numbers of molecules.

Relativity

Einstein's final two 1905 papers concerned relativity, the mind-bending idea about the ticking of clocks and the speed of light that most people associate with Einstein.

In June came the first paper, describing special relativity. In it, Einstein proposed a solution to a problem that had plagued physicists concerned with the spread of light waves. The prevailing belief was that light waves traveled in a fixed medium called the ether, analogous to how water waves travel in the medium of the ocean and sound waves travel in the medium of the air.

Under that belief, the speed of light would vary according to how fast an observer was traveling compared with the ether. Physicists Albert Michelson and Edward Morley famously failed to find that difference in an experiment to measure changes in the speed of light as the Earth moved in different directions compared with this theoretical ether.

Einstein's June paper simply did away with the idea of the ether and said light moves at the same speed--about 186,000 miles per second-- regardless of the speed of the observer. The same beam of light will appear to be a different color to two observers moving at different speeds, but the beam will still be moving at the same speed compared with either of them.

One consequence of this theory is that there is no single universal clock ticking in lockstep across the entire universe. Rather, time passes differently for different clocks moving at different speeds.

In September, Einstein submitted a follow-up paper that introduced another notion: Mass and energy are equivalent, and a change in a particle's mass is associated with a change in its energy. The paper didn't include the famed equation E=mc2, but it laid the groundwork, Stachel said.

It wasn't until 1932, Stachel said, that physicists observed that a tiny amount of mass disappeared in radioactive decay--mass that was converted into the energy of emitted gamma rays or beta particles. A more notable illustration came at the end of World War II, when the mass lost from fissioning atoms became the energy of the explosions over the Japanese cities of Hiroshima and Nagasaki.

Einstein's relativity work wasn't done with the debut of special relativity in 1905. A decade later, the broader general relativity theory emerged, complete with its predictions that gravity could bend the path of light through an effect astronomers now call gravitational lensing.

Where Einstein's rubber hits the road

Einstein's work remade science, but most of its effects on today's technology industry have been indirect.

"It's a stretch to talk about Einstein's contributions to computing," said Tom Theis, director of physical sciences for IBM's research group. But Einstein's work has been relevant to the field, and more need to follow in his footsteps, Theis said: "Continued support of basic research is necessary to lay the foundations for tomorrow's technology."

Robert Chau, director of transistor research and nanotechnology at Intel, deals with Einstein's legacy daily as he tries to create ever-smaller transistors, the on-off switches at the heart of microprocessors.

"It laid down the foundation for modern physics, for what we do today for nanodevice study," Chau said. Quantum mechanical constraints arrived in microprocessor design in about 1990, when electron behavior called "tunneling" began affecting the thinnest transistor components. This quantum mechanical effect leads to wasted power and heating problems and now is a dominant concern.

Einstein's 1905 papers did have some direct connections to today's engineering work. One widely cited example is the Global Positioning System, the navigation technology based on satellite signals with precise timing information. The GPS satellites move fast enough compared with the Earth's surface that relativistic time changes must be taken into effect.

The photoelectric effect also is employed in a technology called X-ray photoemission spectroscopy, which underlies diagnostic tools in the microprocessor industry. "It lets you characterize the interfaces between materials," for example how electrons move between metals and semiconductors in chips, said Rice's Natelson.

Einstein's theories were connected to experimental reality, and physicists taking inspiration should follow that strategy--especially proponents of today's string theory--said Philip Anderson, a Princeton University physics professor whose essay on Einstein appears in Robinson's book.

"In the half a century since his death, the mystique surrounding Einstein has created a cult that in my view starts clever physics students by the thousand off in the entirely wrong direction," Anderson wrote. "The cult makes Einstein into the embodiment of a 'pure' theorist, a genius so brilliant that he snatches his ideas from thin air and achieves revolutionary advances solely by the exercise of mathematical reasoning."

Experiments to prove Einstein's theories are still active. Today, physicists involved with the Laser Interferometer Gravitational Wave Observatory (LIGO) project are trying to verify the existence of gravity waves, which physicists agree is a consequence of Einstein's general relativity theory. Einstein himself became skeptical of the prediction and even tried to disprove it, Stachel said.

It's a measure of the scientist that his ideas are still at the forefront of physics. "In my opinion, he was a true genius," Chau said, "well ahead of his time and, in many aspects, beyond modern days."