View full lesson: http://ed.ted.com/lessons/how-fast-are-you-moving-right-now-tucker-hiatt "How fast are you moving?" seems like an easy question, but it's ...
========== How fast are you moving right now? That seems like an easy question. The first tempting answer is, "I'm not moving." Upon further reflection, you realize that maybe the Earth's motion counts. So, a second tempting answer is, "19 miles/second around the Sun." But then you recall learning that the Sun moves around the center of the Milky Way galaxy, and the Milky Way moves within the Local Group of galaxies, and the Local Group moves within the Virgo Cluster, and the Virgo Cluster moves within... "How fast are you moving?" is not an easy question. When Mission Control tells astronauts how fast they're going, there's always an assumed standard of rest. At the start of the voyage, speeds are given relative to the launchpad. But later, whe...