out the universe until you understand your toaster because there’s a lot of fundamental physics in your toaster. [Laughs] One is, they glow. It sounds obvious. It’s hot so it glows, right? But that dull red glow that gets brighter and brighter as it gets hotter comes from one of the most fundamental laws of physics. That law says that anything that has a temperature above absolute zero is glowing. The type of light it gives out depends on how hot it is. So, the hotter it gets, the shorter the wavelengths.
The other interesting thing in a toaster is an electromagnet. When you push the lever down on the side of the toaster and the toast stays down inside the toaster, the thing holding it down is an electromagnet. The lever connects up a little circuit and sends a current round in a spin. And when a current is going round in circles, the laws of physics say that it will generate a magnetic field. When the toast is done, the current is switched off, the magnetic field goes away, and your toast pops up. You’ve got two of the most essential foundations of physics. And they are both in your toaster!
You say, “The fabric of our civilization is woven together with electromagnetic threads.” Why is electromagnetism so important?
Each of us has three life support systems: We have a body, a planet, and a civilization. Our civilization is keeping us alive now in just the same way that the other two do. We are absolutely dependent on it. And the thing that connects our civilization together is electromagnetism.
There are two forms: visible light—signals we can see from a long way away—which has connected humans for a long time. And now there are the signals we can’t see: radio signals, Wi-Fi signals, mobile phone signals. They’re making a web of electromagnetic waves that we walk through. We don’t see them directly but we use radios, TV, and the Internet, which all depend on them.
One hundred years ago that didn’t exist! Earth was dark in the radio wave and microwave wavelengths. Today, we’ve lit it up with this web of light. Light that we can’t see! But that is communicating! The fabric of our civilization is now stitched together with that communication. If you want to buy something, need medical help, or want to learn something today, you are absolutely reliant on signals being sent to you by electromagnetic waves. We take this web of communication for granted. But we should really appreciate it as a luxury.
In both the U.K. and the U.S., there is a steady decline of high school students opting for physics, particularly among girls. What can be done to make the subject more attractive?
When people hear the word physics, they think quantum weirdness or cosmology, something extremely tiny or very big. What we’re not talking about is all the stuff in the middle. The equations for Newton’s Laws of Motion can be written down quite easily. But those simple laws can help us understand the way our human systems and bodies work, and you can see their effects in the real world. That is a very important reason to study physics.
Physics has this image of being terribly po-faced: a guy with a beard working late at night in a dark room. There’s nothing human in that view of physics. But physics is about making things happen, and we’re not doing well enough at conveying the message that once you understand the framework of the world, you have a different perspective. Even if you’re not going to become a physicist, that is a useful thing for a citizen to have.
Physics is also about how things work. During your lifetime you’re going to be sold toasters or washing machines or cars, and you need to know which questions to ask. Physics is about giving you the basic map of the world.
This interview was edited for length and clarity.