What is time? A deceptively simple question, yet it is the key to understanding relativity. It is also the reason my hair is going grey. When we describe motion, we do so as a function of time.
Ten meters per second, 100 miles per hour. But the mathematical description of velocity is moot. Unless we can define time.
Is time universal? In other words, is there an audible tick-tock throughout the galaxy? A master clock, so to speak, forging ahead like Mozart's metronome?
The answer, my friends, is... Please know, time is not absolute. In fact, for us believing physicists, the distinction between the past, present, and future is but a stubborn illusion.
A lot to consider, I know. I know. But understanding time is essential to understanding relativity. Now, I want you all to close your eyes.
Not to worry, I don't bite. But I am on the lookout for a new pen. Go on.
Close your eyes. To truly grasp the idea of time, we must take a step back and ask, what is light? So journey with me to the sun. Light travels from the sun to the earth through space, yes?
When I was your age, I wanted to know how can something light travel through nothing, space? Let us isolate a light beam and travel alongside it. But let us go faster.
Are you there with me? Faster. Faster. What is time?
Herr Einstein, wake up! I wasn't sleeping, sir. I was thinking. Oh, really?
About what exactly? The secrets of the cosmos, I suppose. I suggest you think about trigonometry instead, with your eyes open.
And sit up! Laws of sines and cosines. c squared equals a squared plus b squared subtract 2 a e to the i minus 3. Equation.
Herr Einstein, are you still too busy contemplating the secrets of the cosmos to solve this equation? Oh, no sir, I've already solved it. Leave.
Now. On what offense? Your mere presence spoils the respect of the class for me! That is not an objective reason! Out!
The natural log of a constant multiplied by x equals the natural log of 1 plus v squared. And since v equals y over x, that gives us the final function. x squared plus y squared minus cx cubed equals zero. And speaking truthfully, sir, your mere presence spoils my respect for the future of Prussian mathematics.
Art.