Traditionally, observers play no special role in physics. Like bird watchers in a perfect hide, we observe the outcome of experiments, or gaze at the stars through our telescopes, taking no part in the action. Modern physics, however, tells a different story ... find out more with these articles and videos.
We all know what we mean when we say that something has happened — well, all except for theoretical physicists. That's because the notion of a "happening" becomes fuzzy when you go down to the foundations of the science. Find out more with these articles and videos.