Idiot of the Day: This one's not too swift


The most remarkable thing about this anecdote, from reader Dan, is that the idiot in question actually got into college:

This wasn't recently, but when I was taking a physics class in college, we were discussing the speed of light. When our instructor started talking about length dilation (how something's length increases as it approaches the speed of light), someone raised their hand and asked, "Is that why a plane gets bigger as it flies toward you?"

Here are some more (correct) facts about the speed at which light travels in a vacuum:

* It's 186,282.397 miles per second, or 299,792,458 meters per second. Should you ever need to recite this second number on command, you can remember it with either of the following mnemonics: "Constant Which We Remember Well Because It's Light's Velocity" (the first letters correspond to the numbers on a phone keypad) or "We Guarantee Certainty, Clearly Referring To This Light Mnemonic" (count the letters of each word).

* It's usually abbreviated "c" (as in E=mc²) which stands for either "constant" or the Latin "celeritas," meaning "swiftness."

* From Wikipedia: "[One] consequence of the finite speed of light is that communications with spacecraft are not instantaneous, especially as distances increase. This delay was significant for the communication of Houston ground control and Apollo 8 when it became the first spacecraft to orbit the Moon: For every question, Houston had to wait nearly 3 seconds for the answer to arrive, even when the astronauts replied immediately. This effect forms the basis of the Global Positioning System (GPS), and similar navigation systems. One's position can be determined by means of the delays in light signals received from a number of satellites, each carrying a very accurate atomic clock, and very carefully synchronized."