Thursday Thirteen: 13 Things You Didn’t Know About Relativity


1. And yet it moves. The idea of relativity was discovered, not invented, by Galileo Galilei in 1639 “when he showed that a falling object behaves the same way on a moving ship as it does in a motionless building.”

2. There’s nothing relative about it. Einstein never used the term “relativity,” instead preferring “invariance theory.” Because the laws of physics appears the same to all observers, there’s nothing “relative” about it.

3. And you thought it was Picard. The idea of the space-time continuum was devised by Hermann Minkowski. From Wikipedia: “By 1907 Minkowski realized that the special theory of relativity, introduced by Einstein in 1905 and based on previous work of Lorentz and Poincare, could be best understood in a four dimensional space, since known as ‘Minkowski spacetime,’ in which the time and space are not separated entities but intermingled in a four dimensional space-time, and in which the Lorentz geometry of special relativity can be nicely represented.”

4. Verdammt! Austrian physicist Friedrich Hasenörl published the basic equation E = mc2 a year before Einstein did, but he failed to connect the equation with the principle of relativity.

5. Now der are two of dem. There are two relativities: Special relativity and general relativity. The former applies to objects moving at constant speed and the latter explains acceleration and gravity.

6. OOPSY. The early version of general relativity had a major error, a miscalculation of the amount a light beam would bend due to gravity.

7. But this one goes up to eleven. No physical object can travel at or faster than the speed of light. The speed of light is generally considered to be a physical speed barrier.

8. It’s all relative? Matter determines how space curves. Curved space determines how matter moves.

9. Not over the hill yet. The age of the universe is widely believed to be 12 to 13 billion years old, and still expanding as a result of the “big bang.” This produces a type of horizon in space, where light has not yet reached Earth from objects further away than 12 to 13 billion light years.

10. Best. Costume. Ever. The Doppler effect causes objects moving away to have their light spectrum red-shifted while objects approaching have their light blue-shifted. This really means that the wavelengths of light they radiate (or reflect) are moved downward or upward on the frequency spectrum. These measurements were the first clue that the universe is expanding.

11. Happy Earth Rotation Day. One second is exactly 9,192,631,770 beats of a Cesium atom, very close to 1/(24 x 60 x 60) of an ‘earth rotation’ day. An earth rotation day is the varying time it takes for the earth to rotate once relative to the sun.

12. Way more productive than checking your Gmail for the 100th time. Einstein’s full-time job at the Swiss patent office meant he had to hash out relativity during hours when nobody was watching. He would cram his notes into his desk when a supervisor came by.

13. Rules are relative too. According to Einstein, nothing travels faster than light, but space itself has no such speed limit; immediately after the Big Bang, the runaway expansion of the universe apparently left light lagging way behind.

Source: Discover Magazine’s 20 Things You Didn’t Know and Einstein’s Relativity Facts.

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