Secrets of the universe

A few years ago, in Berne, I visited the apartment where Einstein wrote his theory of special relativity, which changed our understanding of the world forever. It’s a small apartment, plain and nondescript. The best thing about it is the view. From the window you can see Berne’s huge medieval clock, the Zytglogge. It was this clock which inspired Einstein’s great breakthrough. At the end of every humdrum day, in his dead- end job at Berne’s patent office, he took the tram home, past the Zytglogge, back to this apartment. As he gazed at that clock through the tram window, he wondered: what if his tram could travel at the speed of light? Logically, the light from the Zytglogge should never overtake him. Relatively speaking, it should remain static, just as two trams travelling side by side at the same speed in the same direction remain static in relation to each other.