Discussion of the theory of relativity

For Meetup Saturday, September 21: discussion of the theory of relativity

In 1905, 26-year-old Albert Einstein, then relatively unknown, couldn’t find employment as a professor of physics. To support himself, he found employment as an examiner of patent applications filed by inventors in the Swiss patent office.

He did his real work in his spare time. That year, which came to be known as his miracle year, Annalen der Physik, a prestigious German scientific journal, published four of his papers. Each one revolutionized physics and our understanding of the universe.

The first paper showed that the photoelectric effect means that quantum mechanics applies to light. The second explained how Brownian motion confirms the existence of atoms. The third introduced his theory of relativity. The fourth gave us what is perhaps the most famous equation in physics: E = mc2. (That equation is a consequence of relativity.)

In his entire career, Einstein received only one Nobel Prize (for his paper on quantum mechanics). Many would argue that he should have received four Nobel Prizes for his 1905 papers alone, plus more for later work, especially for his 1915 paper generalizing the theory of relativity to include gravity.

In our meeting on Saturday, September 21, we will discuss his theory of relativity as published in 1905.

We’ll begin with a discussion of motion (all motion is relative; it is not a property of an object considered in isolation), of attempts to measure the absolute speed of Earth’s orbital movement, and of the speed of light, which is the same for all observers, regardless of their motion relative to the source of the light.

The mathematics of the theory is just high-school algebra. With one simple equation we’ll discuss (the Lorentz factor), one can calculate the strange things that happen (from the perspective of an observer) to a traveler moving relative to the observer: the traveler’s time slows down, mass increases, and length in the direction of travel decreases.

We’ll conclude with an explanation of the twin paradox.

I suggest you bring a scientific calculator to the meeting, so that you can do square roots. Your smartphone should have one (you may have to hold it horizontally).

I hope you’ll join us.

Don