UN Declares 2005 as World Year of Physics to Celebrate Einsteinís Miracle Year
Last summer the United Nations General Assembly approved a resolution declaring 2005 as the World Year of Physics. This declaration honors the centennial of the "Annus Mirabilis," or miracle year when a daring young scientist published an extraordinary series of papers that was to launch a scientific revolution and redefine our whole concept of "reality." This was Albert Einstein, who was then 26, and doing physics in his spare time from his work at the Swiss patent office. Luckily for us, he did not stick to his day job.
In 1905, Einstein published an incredible series of scientific papers, remarkable for their breadth and enduring consequences. He took the first step toward a theory of space and time, known today as Special Relativity. He built the foundation for the quantum theory of light, with an analysis of the photoelectric effect. He provided the definitive proof of the existence of atoms, ending a millennia-old debate about the fundamental nature of matter. And he ended that remarkable year by identifying the equivalence of matter and energy, forever afterward encapsulated in the worldís most famous equation, E = mc2. If he had been run over by a horse-drawn carriage at yearís end, history might still have acknowledged him as the twentieth centuryís greatest genius. Incredibly, his finest work was yet to come. He would dominate science for the next two decades and become Earthís most famous individual.
Then his star began to fade, and his prestige was eclipsed by other luminaries. Had he become a relic of the past, outshone by brighter minds now hard at work building twentieth century science? Or had he simply leaped ahead to set the foundation for the science of the twenty-first century? Read on while we figure that out.
The scientific revolution launched in 1905 by Einstein's work was so broad it's hard for us to imagine now what life would be like had it not occurred. The quantum theory--the laws describing the microscopic world of atoms and their constituents--and relativity theory--the laws of how space and time and matter and energy behave, are the two main pillars of modern science. Without them we would not understand chemical bonds. Forget about modern drugs and materials. We would not know about the building blocks of matter and how they behave. Forget about that MRI scan used to save your grandmotherís life or the laser eye surgery that cured your auntís cataracts. We would not understand how electric currents flow through matter. Forget about the computer on your desk and about researching on the internet. For that matter, forget about the computer in your coffeemaker! While we're on the topic of coffeemakers, forget about the electricity from a nuclear reactor that brews your coffee. Forget too about the global positioning system that allows planes and ships to travel the world or the pocket GPS receiver that can guide a hunter lost in the woods to safety. Gazing at the sky, we would not understand how energy comes from the sun, how the heavens work, or how we came to be here.
Einsteinís greatest opus, forged in the years from 1907 to 1915, was the General Theory of Relativity. Its scope was literally as big as the universe. Special Relativity showed that concepts of time and space were relative. Scientists in a spaceship laboratory hurtling past Earth at near the speed of light, and their colleagues in an earthbound laboratory, would both agree that their experiments obeyed the laws of physics. But they would tell vastly different stories of what they saw outside their windows, peering into the other groupís lab. Clocks would slow down and rulers would shrink. Everything was relative, everything except the speed of light. Common sense argued that this was total rubbish; but experiments showed that in fact it was true. Yet inside this revelation there lurked a dark secret. It only worked if one ignored gravity. Two and a half centuries earlier, Isaac Newton had described how gravity behaved. But no one had ever described how it actually worked. Einstein felt compelled to do so.
Einstein discovered a vital clue as to how gravity could work. Imagining a laboratory moving through space, he realized that all the effects of gravity were equivalent to the effects of acceleration. The mathematician, Herman Minkowski, a professor at the Swiss institute where Einstein had studied, provided another crucial piece of the puzzle. Einstein developed Special Relativity by following physics. But Minkowski discovered a mathematical pattern in Einsteinís work. The relationships between space and time in Einsteinís theory traced the same patterns as the mathematical description of how we see an object from different perspectives. In this case, the physics was telling us of a pattern of rotations in four dimensions: the three familiar dimensions of space--length, width and heigh--and an oddly defined dimension of time.
Einstein probed for the consequences of this newfound symmetry. If Special Relativity could be explained by geometry, could geometry also provide a picture uniting gravity and acceleration? With singular focus, Einstein eventually discovered the key to the puzzle. It was the shape of space and time! In General Relativity, the flow of matter and energy through space and time follows from the shape of space and time. This shape results from the warping of space and time, caused by the matter and energy in space and time. Matter, energy, space, time and gravity are intricately braided together, always and everywhere. The mere presence of matter in space should cause light to move through space like it was moving through a cosmic window glass distorted by bubbles and defects. These space warps should bend the light from distant stars. In 1919, the bending of starlight was first observed in photographs of stars near the limb of the Sun, taken during a total eclipse. The news made banner headlines in newspapers across the globe. Reality, it seemed, was not as it had appeared to be!
General Relativity provided the framework for the new science of cosmology--the history of our universe. Einstein himself wrote one of the first papers in this field, and other thinkers soon followed. But the emergence of quantum mechanics in the 1920s would eventually eclipse relativity and cosmology as the "hot" fields of science. Although he laid the foundation for quantum mechanics and produced, with the Indian scientist S. Bose, a seminal work in quantum theory predicting a new form of matter, Einstein found the emerging theory distasteful. True, it accurately described the way the world worked on the microscopic level of atoms and subatomic particles, but it described a world where chance overruled order and predictability. Einstein believed there must be a better way. He divorced himself from the rest of twentieth century science and worked, reclusively, toward a master theory where relativity and quantum theory--the two great theories of modern science--would be joined. He would live out the last quarter century of his life in a scientific wilderness, questing for a "Theory of Everything."
Fast-forward fifty years. Following Einsteinís death in 1955, technological advances ushered in a "golden age" of experimental relativity. Einsteinís theory was found to be a masterpiece of precision. Seemingly fantastic aspects of the theory, such as black holes, have been found to exist throughout our universe. Monumental laser interferometers, like LIGO, now search the heavens for evidence of the spacequakes--those ripples in space-time known as gravitational waves--created by such phenomena as the forming or colliding of black holes and neutron stars. Cosmology enjoyed a rebirth as evidence for the Big Bang mounted. In 1964, relic light from the Big Bang was first detected. By 2003, we had detailed two-megapixel images of our infant universe when the first atoms formed! But the euphoria of discovery awakens a new respect for the last pursuit of Einsteinís later years. First comes the deepening realization that, in the earliest moments of the Big Bang, the macroscopic world we occupy today and the microscopic world were the same. To understand how the structure and natural history of our universe came to be, we will need to join together quantum theory and relativity. Finally, in 1998, two independent groups of astronomers announced a nearly unthinkable surprise: the expansion of the universe, long thought to be slowing, is actually speeding up. Some weird form of energy appears to be acting like an "anti-gravity," driving space to expand. The universe may be running away and we have no explanation why! Is it caused by the type of anti-gravity that Einstein once included in his theory, but later cast out, declaring it the greatest mistake of his life? Is it caused by some other new physics that comes from a bigger and better theory of everything? We will need to wait for the twenty-first centuryís answer.
Fittingly, the US has adopted "Einstein in the 21st Century" as its theme for 2005, the World Year of Physics. No effort better reflects this theme than the search for gravitational waves, so it should come as no surprise that LIGO is playing a lead role in the national celebration. LIGO scientists have developed a free program, called Einstein@Home, to allow anyone--anywhere in the world--with a personal computer and internet connection to help search our galaxy for undiscovered neutron stars, using LIGO to sense their telltale ripples in space-time. You can use your idle computer cycles to help make history! A roll-out event was held at the LIGO Hanford Observatory in early January, and a monthly series of "World Year" physics and astronomy events for people of all ages has been planned. Details can be found at the LHO World Year 2005 Public Events page.
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