dilation

WHEN it comes to making decisions, timing can be everything, but it is often beneficial to conceal the decision that has been made. Take a game of poker, for instance: during each round, the player has to decide whether to bet, raise the stakes, or fold, depending on the hand they have been dealt. A good player will have perfected his "poker face", the blank expression which conceals the emotions he feels and the decisions he makes from the other players sitting at the table. Increasing numbers of researchers are using brain scanning techniques to perform what is commonly referred to as "…

There's a graduate student that I'm sort-of mentoring/working with at Arizona, named Xiaoying Xu (hi Xiao!). She's bright and curious, and she asks some very good questions. She asked me one yesterday that's pretty tough to wrap your head around: How do I explain to someone why light doesn't age? Well, here on Earth, time progresses at a certain speed. That is, if I measure how many seconds tick by as the Earth revolves once around the Sun, I'll get 31,556,926 seconds. (31,558,150 if I'm measuring a sidereal year.) But let's say in the course of that year, I put you on a rocket ship, and…