![]() 1904: Measuring Light From a Moving Train That’s where he resolved to crack the paradox once and for all. This problem would bug Einstein for another 10 years, all the way through his university work at ETH and his move to the Swiss capital city of Bern, where he became an examiner in the Swiss patent office. But nothing like that had ever been observed. Basically, relativity said that the laws of physics couldn’t depend on how fast you were moving all you could measure was the velocity of one object relative to another.īut when Einstein applied this principle to his thought experiment, it produced a contradiction: Relativity dictated that anything he could see while running beside a light beam, including the stationary fields, should also be something Earthbound physicists could create in the lab. Worse, stationary fields wouldn’t jibe with the principle of relativity, a notion that physicists had embraced since the time of Galileo and Newton in the 17th century. The laws were (and are) quite strict: Any ripples in the fields have to move at the speed of light and cannot stand still-no exceptions. For starters, such stationary fields would violate Maxwell’s equations, the mathematical laws that codified everything physicists at the time knew about electricity, magnetism, and light. If he were to run alongside it at just that speed, Einstein reasoned, he ought to be able to look over and see a set of oscillating electric and magnetic fields hanging right next to him, seemingly stationary in space. In that happy environment, he soon he found himself wondering what it would be like to run alongside a light beam.Įinstein had already learned in physics class what a light beam was: a set of oscillating electric and magnetic fields rippling along at 186,000 miles a second, the measured speed of light. (Also see “ Why the FBI Kept a 1,400-Page File on Einstein.”)įirst, though, Einstein decided to put in a year of preparation at a school in the nearby town of Aarau-a place that stressed avant garde methods like independent thought and visualization of concepts. 1895: Running Beside a Light Beamīy this point, Einstein’s ill-disguised contempt for his native Germany’s rigid, authoritarian educational methods had already gotten him kicked out of the equivalent of high school, so he moved to Zurich in hopes of attending the Swiss Federal Institute of Technology (ETH). ![]() ![]() Here’s how Einstein got started on his thought experiments when he was just 16, and how it eventually led him to the most revolutionary equation in modern physics. To bring his process to life, National Geographic created an interactive version of one of Einstein’s most famous thought experiments: a parable about lightning strikes as seen from a moving train that shows how two observers can understand space and time in very different ways. (Read “ 10 Things You (Probably) Didn’t Know About Einstein.”) He liked to think visually, coming up with experiments in his mind’s eye and working them around in his head until he could see the ideas and physical principles with crystalline clarity. That’s because fancy math was never the point for Einstein. His text is plain and clear, and his equations are mostly just algebra-nothing that would bother a typical high-schooler. Albert Einstein’s theory of relativity is famous for predicting some really weird but true phenomena, like astronauts aging slower than people on Earth and solid objects changing their shapes at high speeds.īut the thing is, if you pick up a copy of Einstein’s original paper on relativity from 1905, it’s a straightforward read.
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