Through the end of this year, we're counting down your favorite articles. The metric used is the total number of page views ...

Time travel has long lived in the realm of fantasy, but a growing body of research is quietly shifting it into a serious ...

Shattered glass does not leap back into your hand. Smoke from a match does not gather itself and crawl back inside. In everyday life, time feels like a one-way street, and you only get one chance to ...

You have probably seen the images of the surface of Mars, beamed back by NASA's rovers. What if there were a time machine ...