Storm in a Teacup: The Physics of Everyday Life(2)

I studied physics because it explained things that I was interested in. It allowed me to look around and see the mechanisms making our everyday world tick. Best of all, it let me work some of them out for myself. Even though I’m a professional physicist now, lots of the things I’ve worked out for myself haven’t involved laboratories or complicated computer software or expensive experiments. The most satisfying discoveries have come from random things I was playing with when I wasn’t meant to be doing science at all. Knowing about some basic bits of physics turns the world into a toybox.

There is sometimes a bit of snobbery about the science found in kitchens and gardens and city streets. It’s seen as something to occupy children with, a trivial distraction which is important for the young, but of no real use to adults. An adult might buy a book about how the universe works, and that’s seen as being a proper adult topic. But that attitude misses something very important: The same physics applies everywhere. A toaster can teach you about some of the most fundamental laws of physics, and the benefit of a toaster is that you’ve probably got one, and you can see it working for yourself. Physics is awesome precisely because the same patterns are universal: They exist both in the kitchen and in the farthest reaches of the universe. The advantage of looking at the toaster first is that even if you never get to worry about the temperature of the universe, you still know why your toast is hot. But once you’re familiar with the pattern, you will recognize it in many other places, and some of those other places will be the most impressive achievements of human society. Learning the science of the everyday is a direct route to the background knowledge about the world that every citizen needs in order to participate fully in society.

Have you ever had to tell apart a raw egg and a boiled egg without taking their shells off? There’s an easy way to do it. Put the egg down on a smooth, hard surface and set it spinning. After a few seconds, briefly touch the outside of the shell with one finger, just enough to stop the egg’s rotation. The egg might just sit there, stationary. But after a second or two, it might slowly start to spin again. Raw and boiled eggs look the same on the outside, but their insides are different, and that gives the secret away. When you touched the cooked egg, you stopped a whole solid object. But when you stopped the raw egg, you only stopped the shell. The liquid inside never stopped swirling around, and so after a second or so, the shell started to rotate again, because it was being dragged around by its insides. If you don’t believe me, go find an egg and try it. It is a principle of physics that objects tend to continue the same sort of movement unless you push or pull on them. In this case, the total amount of spin of the egg white stays the same because it had no reason to change. This is known as conservation of angular momentum. And it doesn’t just work in eggs.

The Hubble Space Telescope, an orbiting eye that has been whooshing around our planet since 1990, has produced many thousands of spectacular images of the cosmos. It has sent back pictures of Mars, the rings of Uranus, the oldest stars in the Milky Way, the wonderfully named Sombrero Galaxy, and the giant Crab Nebula. But when you’re floating freely in space, how do you hold your position as you gaze on such tiny pinpoints of light? How do you know precisely which way you’re facing? Hubble has six gyroscopes, each of which is a wheel spinning at 19,200 revolutions per second. Conservation of angular momentum means that those wheels will keep spinning at that rate because there is nothing to slow them down. And the spin axis will stay pointed in precisely the same direction, because it has no reason to move. The gyroscopes give Hubble a reference direction, so that its optics can stay locked on a distant object for as long as necessary. The physical principle used to orient one of the most advanced technologies our civilization can produce can be demonstrated with an egg in your kitchen.

This is why I love physics. Everything you learn will come in useful somewhere else, and it’s all one big adventure because you don’t know where it will take you next. As far as we know, the physical laws we observe here on Earth apply everywhere in the universe. Many of the nuts and bolts of our universe are accessible to everyone. You can test them for yourself. What you can learn with an egg hatches into a principle that applies everywhere. You step outside armed with your hatchling, and the world looks different.

In the past, information was treasured more than it is now. Each nugget was hard-earned and valuable. These days, we live on the shore of an ocean of knowledge, one with regular tsunamis that threaten our sanity. If you can manage your life as you are, why seek more knowledge and therefore more complications? The Hubble Space Telescope is all very nice, but unless it’s also going to look downward once in a while to find your keys when you’re late for a meeting, does it make any difference?

Humans are curious about the world, and we get a lot of joy from satisfying our curiosity. The process is even more rewarding if you work things out for yourself, or if you share the journey of discovery with others. And the physical principles you learn from playing also apply to new medical technologies, the weather, mobile phones, self-cleaning clothes, and fusion reactors. Modern life is full of complex decisions: Is it worth paying more for a compact fluorescent light bulb? Is it safe to sleep with my phone next to my bed? Should I trust the weather forecast? What difference does it make if my sunglasses have polarizing lenses? The basic principles alone often won’t provide specific answers, but they’ll provide the context needed to ask the right questions. And if we’re used to working things out for ourselves, we won’t feel helpless when the answer isn’t obvious on the first try. We’ll know that with a bit of extra thinking, we can clarify things. Critical thinking is essential to make sense of our world, especially with advertisers and politicians all telling us loudly that they know best. We need to be able to look at the evidence and work out whether we agree with them. And there’s more than our own daily lives at stake. We are responsible for our civilization. We vote, we choose what to buy and how to live, and we are collectively part of the human journey. No one can understand every single detail of our complex world, but the basic principles are fantastically valuable tools to take with you on the way.