The Simplicity of Physical Law

a rigorous basis for quantitative thinking

I often tell my daughter there are only a handful of important physical laws that model a disproportionate share of our expectations about the natural world. These laws concern conservation, waves and dissipation.

Although it often escapes my memory where my eyeglasses are, they are unquestionably as I left them last night when I took them off. The cold water in my vacuum-sealed Swell bottle stays cold. The chemical energy stored in gasoline can be converted to a Sunday drive and a hot engine. The battery in an unused smoke alarm lasts a long, long while and, try as we might, stopping the world and getting off won’t ever be realized. Conservation.

Reflection, refraction and interference are all phenomena that can be understood in terms of waves. ‘Objects in mirror are closer than they appear’ puzzled me as a child. Sunlight passing through old bevelled glass on our front door always made beautiful rainbows on the floor. When warm summer rain falls in puddles, the smell of worms, and overlapping rings of ripples give way to childhood memories. Waves.

Hot tea gets cold and iced tea gets warm. A few grains of salt disappear in boiling water. Balloons pop but never un-pop and the comforting smell of toast in the morning slowly goes away. Dissipation.

This little rant is a good deal more than half of the physics that students shy away from. I wish they wouldn’t.