Seminar Explores Theory of Relativity

Imagine one day you wake up and you are really craving a delicious crepe, so you decide to drive to the Skinny Pancake in Burlington. If, like me, you are not a native Vermonter, you would probably use some sort of GPS to aid you in your journey. However, you might take for granted how much physics goes into ensuring that your GPS can accurately guide you from point A to point B. More specifically, if your GPS did not account for the effects of the relative motion between your car and the satellites that are reporting your position, then, at the end of your drive, you would be approximately a mile from your intended destination, and you would be deprived of a crepe.

But what exactly does it mean that your car is moving relative to a satellite and how does that, in turn, affect your ability to arrive at Skinny Pancake? These are the exact questions addressed by Benjamin F. Wissler Professor of Physics Richard Wolfson and Professor of Physics Noah Graham in a joint lecture titled “A Century of Relativity: A Global Perspective,” which examined the implications of Einstein’s theory of relativity.

This November marks the hundred-year anniversary of the theory. In order to celebrate this milestone, the Rohatyn Center for Global Affairs sponsored the lecture. This talk represents the first in the Center’s new and exciting program, “The Future of the Past,” which seeks to demonstrate the past continuing to impact our lives.

The theory of relativity is composed of two theories, the theory of special relativity and the theory of general relativity. Professor Wolfson began the lecture by offering an overview of the key aspects of the theory of special relativity. Pulling from his book, Simply Einstein: Relativity Demystified, Wolfson described how the famous expression E = mc2 is not central to the theory itself, but instead was simply added as a footnote, a literal afterthought. It is the relativity principle that is really at the heart of the theory. Before Einstein, it was assumed that physical reality was the same for everyone regardless of their state of motion. Einstein showed that this is false and that physical reality is only relative to your state of motion. Because of this, statements such as “I am moving” or “I am stationary” are meaningless. Motion can only be described as relative to something else.

The effects of this can be seen if you imagine a game of tennis. Professor Wolfson described how, if you go to play tennis on the courts outside of Proctor, you have certain expectations for how the ball will bounce, and what will happen after you hit the ball with your racket. If you were then transported to a tennis court inside of a cruise ship that is moving at a constant speed relative to the Proctor tennis courts, you would still expect the same physical laws to apply. Intuitively, you know that the way that the tennis ball bounces will not suddenly change on the cruise ship. This is because you are still stationary relative to the cruise ship, similar to how you were stationary relative to the Proctor tennis courts. Imagine then, that you are transported to Jupiter, which is moving thousands of meters per second relative to the Proctor tennis courts. The same physical laws will still apply because you are stationary relative to Jupiter. Wolfson attributes the unchanging nature of your game of tennis to the relativity principle. According to the principle the laws of physics are the same for everyone as long as they are experiencing uniform motion. The relativity principle also applies to electromagnetic phenomena. A microwave, which relies on electromagnetic radiation, will work just as well in Proctor, as it would on the cruise ship or on Jupiter. This means that Matt Damon can microwave himself some delicious Easy Mac while he waits for us to rescue him from wherever he is stranded next.

The consequences of the relativity principle are somewhat mind-boggling. If all motion is relative, then the space and time you are experiencing in your frame of reference are not absolutes. This means that if you purchase a new hot-rod convertible and take it out for a spin on the freeway, the clock within your car would appear to be ticking more slowly from the perspective of someone stationary on the side of the freeway, holding a clock of their own. However, from your perspective, you and your snazzy car are stationary and the freeway is moving underneath you. Therefore, you would see that the clock held by the person standing on the side of the freeway ticking more slowly than the clock within your car. Wait, what? One of the crazy consequences of special relativity is that both time and space are dependent on your state of motion. One of the invariants is the speed of light. This means that both you in your hot-rod and the person on the side of the freeway will measure the same value for the speed of light, even though you are experiencing relative motion. So why don’t we see the effects of this in everyday life? The effects of the relativity principle only become apparent when the relative speeds approach the speed of light, something we almost never experience in our daily lives, except for example, when you are using a GPS to navigate towards your delicious crepe because the satellite involved in GPS technology moves at high velocities as it orbits.

If the effects of special relativity seem strange to you, then the effects of general relativity will appear absolutely absurd. In general relativity, Einstein theorized that space-time itself is curved. Massive objects, such as our sun, warp space-time and pull less massive objects, such as the earth, towards them. Einstein correctly claimed that gravity is attributed to the existence of the bending of space-time. Professor Graham, a theoretical physicist, explained how we would need a four-dimensional map, three dimensions of space and one dimension of time in order to accurately represent the shape of our universe. Not only does General Relativity require the existence of higher dimensions, but it also predicted a number of strange objects, such as black holes.

According to Professor Graham, perhaps the most astounding aspect of the theory of relativity is that Einstein derived it without any experimental evidence. It is one of the occurrences where science was just as creative as art. Take a moment to appreciate that. Einstein was able to completely reimagine the very shape of the universe he existed in based only on his intuition about how physical laws should work. So, the next time you are driving to eat a delicious French pancake, or anywhere else for that matter, take a moment to appreciate the beautiful theory that your navigation relies on and the brilliant man that is credited for its creation. Even a century after its creation, Einstein’s theory of relativity continues to captivate and amaze.