Celebrating 101 years of the general theory of relativity
Five leading physicists from around the world share what Einstein's masterpiece means to them.
Ask somebody on the street what's the first thing they think about when you say, "Albert Einstein." Most people will bring up the genius' famous general theory of relativity, which turns 101 this month. On Nov. 25, 1915, Einstein presented the theory to the Prussian Academy of Science in Germany. To commemorate the anniversary, we asked some of the world's leading physicists to reflect on what the theory means to them.
Last year we celebrated the 100th anniversary of Einstein’s intellectual masterpiece, his general theory of relativity. On the 101st anniversary of the theory, it is appropriate to recall that Einstein was not only a great scientist. He was also a missionary of science, committed to explaining his work to broad audiences. Shortly after completing his theory, he wrote to his friend Michele Besso: “The great success in gravitation pleases me immensely. I am seriously contemplating writing a book in the near future on special and general relativity theory ... if I do not do so, the theory will not be understood, as simple though it basically is.”
– Hanoch Gutfreund is the academic director of the Albert Einstein archives at Hebrew University in Jerusalem.
I think Einstein's theory is beautiful. The idea that space and time can be curved, squeezed and stretched is so hidden from how we experience our day-to-day lives, and yet, if we just reorient our thinking a little bit, it's so profoundly simple. To me, that's the sign of a good scientific theory – it simplifies our understanding of the universe, broadens our capabilities, and leads us to predictions we would have never imagined.
– Kathryn Williamson is an assistant professor of physics and is organizing a large Einstein event in April.
Since I was a small child, I was fascinated with the idea of science as a way of understanding how everything works. Einstein’s theory of relativity is a particularly satisfying example of science in action: a fundamentally new way of understanding space, time and gravity, beautiful in its simplicity, mathematically satisfying. And best of all, it seems to successfully describe physical phenomena on a wide range of scales and gravitational field strengths. General relativity and quantum mechanics are my two favorite subjects to teach because they are so fundamental to our current understanding of the universe, and it’s an amazing experience as a teacher to see young physics students learning how to go beyond the standard “classical” physics intuition that we develop just by watching gravity in action. My entire research program is based on measurement of phenomena that require general relativity for a proper understanding, so it’s really the underpinning of all my work.
– Rachel Madelbaum is an associate professor of physics at Carnegie Mellon University.
The most striking thing about modern physics – beyond its remarkable predictive power – is how fundamentally it challenges our most fundamental and intuitive notions of what reality is like. For example, each of us has a personal sense that "now" is a meaningful concept that all people share. The past is said to be behind all of us, the future is in front of all of us, and "now," consisting of a snapshot of the entire universe and all the other people around us and moving forward with each passing second, somehow feels more real than either the past or the future. But Einstein's relativity leads to a breakdown in this intuitive sense of "now" for observers moving at extremely large speeds relative to one another, because spatially separated events that are simultaneous to one such observer won't be to another such observer. This breakdown in the existence of an objective "now" shared by all people, with its implications for free will, probability and conscious experience, becomes more unsettling to me the more I've thought about it. On the other hand, whatever trouble is going on in our lives here on Earth, perhaps it's some small consolation to know that to a faraway particle traveling away from Earth at nearly at the speed of light, our present day is already in the far past.
– Jacob Barandes is a physics lecturer and the associate director of graduate studies at Harvard University.
Sean T. McWilliams
General relativity is in many ways the ultimate demonstration of the limitless potential of human imagination. Prior to Einstein, there was very little practical reason to revisit Newton's laws, but Einstein found them philosophically unsatisfying, even though they described his world perfectly well, and so he set about developing an alternative based on generalizing his earlier theory of special relativity to accelerated motion. The fact that this generalization did not end up taking the form of a small tweak to his original theory, but instead was a complete rethinking of the fabric of reality, speaks to Einstein's confidence as much as his brilliance. He had exactly one piece of observational evidence, the anomalous perihelion advance of Mercury, but his ultimate theory has successfully predicted the existence of black holes, the Big Bang and most recently, gravitational waves.
– Sean T. McWilliams is a theoretical physicist at West Virginia University.
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Related Topics: Albert Einstein