Tracking time is one of those things that seems easy, until you really start to get into the details of what time actually is. We define a second as 9,192,631,770 oscillations of a cesium atom.

In 1916, only a year after Albert Einstein had published his general theory of relativity, Karl Schwarzschild used ...

Add Yahoo as a preferred source to see more of our stories on Google. "That's the Pinwheel galaxy," I said. The name is derived from its shape – albeit this pinwheel contains about a trillion stars.