World Year of Physics Celebrates Einstein’s Theories
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RAY SUAREZ: One hundred years ago this month, Albert Einstein turned our understanding of the world on its head. It was June 1905 when Einstein published his breakthrough theory on the relativity of time and space. This followed papers published earlier in the year, showing that light is made up of tiny particles and that all matter consists of atoms.
Later in September, Einstein unveiled his famous theory, e=mc squared, or energy equals mass times the speed of light squared. Arguably, Einstein’s accomplishments in 1905 constitute the single most important and impressive year in the history of science. One hundred years later, international scientific organizations have declared this the world year of physics, in Einstein’s honor.
So just how revolutionary were these ideas and where do they lead? I talked recently with physicist and writer Alan Lightman, an adjunct professor of humanities at the Massachusetts Institute of Technology. We met in a physics lab at Thomas Jefferson High School for Science and Technology in Alexandria, Virginia. He’s the author of numerous essays and books on science and several works of fiction, including the novel, “Einstein’s Dreams.”
Take us back to that world before the spring of 1905. What was it that Einstein figured out that changed everything?
ALAN LIGHTMAN: Well, he made several great discoveries in 1905. But I think the most profound was a new understanding of time and space. Almost all physicists before and after had dealt with individual phenomena and forces. But Einstein created the stage on which those forces play out their parts. There’s really nothing more fundamental than time and space. That’s the arena in which everything takes place. We have this visceral sense of the absolute nature of time, and Einstein changed all of that.
RAY SUAREZ: The theory of relativity is 100 years old this month. But I’ll bet a lot of people would be hard pressed to explain what it is. So, in a short, sweet way, what is the theory of relativity?
ALAN LIGHTMAN: The fundamental idea of relativity is that there is no condition of absolute rest — that any motion is relative to another body. If you’re driving in a car at 70 miles per hour, what that means is you’re going at 70 miles per hour relative to the road, to the highway.
But the highway is stuck to the Earth, the Earth is spinning around, it’s orbiting the Sun at a certain speed, the Sun is moving around the center of the galaxy at another speed, the galaxy is traveling through space. And you cannot really say how fast your car is going in any absolute sense, only how fast it is going relative to the highway. And that’s where the word relativity comes from.
RAY SUAREZ: Once the cat’s out of the bag in spring 1905, what is released by that knowledge?
ALAN LIGHTMAN: Well, all of physics had to be reformulated after Einstein, because all the forces and phenomena that physics dealt with involve space and time. An object cannot exist without moving through time at a minimum, and so all of the equations of physics had to be rewritten to incorporate this strange new notion of the relative nature of time — that different clocks in motion relative to each other tick at different rates.
RAY SUAREZ: And can we point to things in our daily common lives that are the intellectual spawn of that idea?
ALAN LIGHTMAN: Most common everyday phenomena don’t really depend on relativity because the effects are too tiny at the small earthly speeds that we travel at. One of Einstein’s other theories in 1905, his work on quantum mechanics, has many more applications.
Almost everything that we do in the electronics industry, computers, silicon chips, all of that depends upon quantum mechanics and so was profoundly impacted by Einstein’s work in an applied sense. Relativity doesn’t have that much of an applied effect because our speeds are slow, but it is very important in all of our theories in physics like the electro weak theory, modern gravitation, physics string theory. All of these new theories in physics depend upon relativity.
RAY SUAREZ: So everybody who has just watched me and you talking on television can thank Albert Einstein, at least a little, for that.
ALAN LIGHTMAN: A little bit.
RAY SUAREZ: I think if we asked the first 100 people we met on the street about Einstein, a lot of them would come up with the idea that he is somehow the intellectual father of the atomic bomb, and maybe a subset of that number would say e=mc squared, but they wouldn’t know what “e” is or “m” or “c.” How is that?
ALAN LIGHTMAN: Well, associating Einstein with the atomic bomb is somewhat erroneous, because his work, although it showed that energy could be obtained from mass in the famous formula e=mc squared and quantitatively express how much energy from how much mass, that formula was really not necessary to create the atomic bomb; it would have been created without the formula at all.
So Einstein’s work did not lead to the atomic bomb. It led to so many other things, though. It led to, as I said, the re-conception of time and space; it led to the understanding that light is not a smooth stream of energy but actually comes in individual particles. If we could hear light, it would sound like the pitter-patter of individual rain drops falling on a tin roof. And that idea that light came in little particles led to quantum physics, which is another major revolution of 20th century physics.
RAY SUAREZ: You in “Einstein’s Dreams,” I think, get at the artist in the conceptual thinker that he was. But is there a sort of steel spine?
ALAN LIGHTMAN: Einstein was enormously self-confident, and he did have a steel spine in terms of his belief and his own thinking about physics. Even when experiments contradicted his equations, he believed the equations and not the experiments.
Of course, ultimately, if one after another experiment disagrees with his work, eventually he has to throw in the towel and say that his theory is wrong. But when in doubt, he would always give the preference to his is theory. He had supreme self-confidence in his ability to sniff out the true nature of the world, and he did that not by experiment, but just by thought, by pure thought.
He did this wonderful thing called the Gedanken experiment, which from the German translates to “thought” experiment. And if he needed an experiment, he would imagine it, very cheap form of experiment. But he would just imagine, like an elevator falling through space with its cable cut, and imagine what happened if you did an experiment inside that freely falling elevator.
RAY SUAREZ: But he turned out to be right in a remarkable number of times.
ALAN LIGHTMAN: He was right most of the time. He was not right all the time. And it’s interesting the way he behaved when he went wrong. He was wrong about quantum mechanics, even though ironically he was one of the pioneers of quantum mechanics. He never accepted the uncertainty that is intrinsic, the fact that quantum mechanics depends upon probabilities and not certainties.
He never could accept that fundamental feature of quantum mechanics and resisted the advance of modern physics. From the 1920s on, Einstein became more and more isolated working on his own theories that did not include quantum mechanics. And he would not admit that quantum mechanics was probably a very good description of the world, so he kind of got left in the dust from the 1930s on and became like King Lear, just sort of wandering in the desert.
RAY SUAREZ: Alan Lightman, thanks a lot for being with us.
ALAN LIGHTMAN: Thank you for having me, Ray.