https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=Spag 2026-05-19T06:36:14Z User contributions MediaWiki 1.30.0 https://www.explainxkcd.com/wiki/index.php?title=1233:_Relativity&diff=42850 2013-07-04T12:42:31Z

<p>Spag: </p> <hr /> <div>{{comic<br /> | number = 1233<br /> | date = July 3, 2013<br /> | title = Relativity<br /> | image = relativity.png<br /> | titletext = It's commonly believed that Lorentz contraction makes objects appear flatter along the direction of travel. However, this ignores light travel times. In fact, a fast-moving butt would appear rotated toward the observer but not substantially distorted. Shakira was right.<br /> }}<br /> <br /> ==Explanation==<br /> ''Gedankedank'' is a humorous {{w|portmanteau}} of ''Gedankenexperiment'' (German for &quot;{{w|thought experiment}}&quot;) and ''badonkadonk'' (slang term for [http://urbandictionary.com/define.php?term=badonkadonk an attractive, round butt]). <br /> <br /> {{w|Albert Einstein}} often used thought experiments to explore scientific hypotheses too impractical or impossible to actually perform, in order to examine their consequences. Moving close to the speed of light, '''c''', is nigh-impossible with existing technology; and according to Einstein's theory of {{w|special relativity}} accelerating a mass exactly to '''c''' ''is'' impossible. Einstein is well known not to have cared about his appearance, he even showed his tongue to a photographer, so it is unlikely that he pondered how relativistic velocity would affect the appearance of his butt.<br /> <br /> {{w|Lorentz contraction}} is a consequence of special relativity, whereby objects contract in the direction of travel. An object traveling exactly at '''c''' (rather than ''near'' light speed) would be squished completely flat. It would also have infinite mass, infinite energy, and experience no passage of time until slowed by an outside force.<br /> <br /> The appearance of rotation while moving close to the speed of light is known as {{w|Terrell rotation}}. The title text then connects this rotation to the Shakira song &quot;{{w|Hips Don't Lie}}&quot;.<br /> <br /> ==Transcript==<br /> :[A box is shown with Albert Einstein in a thinking pose.]<br /> :Albert Einstein: If I were traveling at the speed of light, my butt would look ''awesome.''<br /> :Einstein was famed for his ''Gedankedank.''<br /> <br /> {{comic discussion}}<br /> [[Category:Comics featuring real people]]<br /> [[Category:Physics]]<br /> [[Category:Portmanteau]]</div>

Spag