My editor hates it when I use the word "stuff." Since I write about physical science, he thinks I should use something more scientific, like "atoms" or "energy" or "matter."
But often, "stuff" is the only word that describes what I mean.
Take the stuff we call empty space, for example. The vacuum is a major player today in physics. It has shape. It has properties. It can be frozen or melt. It has a history, and physicists think it has changed significantly over time. And yet, by definition, it's nothing. Not energy, not matter. Just stuff.
And what about mind? Is it matter? Clearly, the brain is composed of matter in the form of neurons, and the atoms and molecules that make them up. But just as clearly, there is something more involved.
After all, every atom in the average body is replaced every half a dozen years or so. What, then, is a person? What and where are thoughts and memories to be found?
A concept like mind--as opposed to the physical brain--cannot be described as energy or matter alone. Instead, it's an exotic kind of stuff, something like a flickering candle flame. Even though the exact molecules of wax or photons of light in the flame are constantly changing, the form stays remarkably consistent. It's an evolving pattern of matter/energy stuff--real enough to touch, even though you can't quite put your finger on it.
Attempts to assign labels more specific than "stuff" are often misleading because so many phenomena combine aspects of both. What do you call a fire, for example? Or an egg in the process of cooking? Some curious alchemy of matter and energy takes place that transforms liquid yolk to solid egg salad, solid wood to light and carbon dioxide. What do you call the caldron of atoms and nuclear fire that fuels the shining of stars?
Carl Sagan once said we were star stuff--not star matter, or star energy. It takes more than matter or energy alone to make exploding stars or chemical elements. It takes the energy locked in matter, and the matter forged from energy, to arrange and secure the particles in place.
It was Albert Einstein, of course, who proved that matter is only a frozen form of energy, and matter and energy are only different forms of the same stuff. Fires and nuclear explosions and the slow metabolic burning of calories in our bodies turn matter into energy; plants take energy from the sun and turn it into matter. You can add some energy to common soot and cook up the toughest stuff in the universe--diamond.
Einstein also showed that space and time coexisted in an inseparable stuff-like state called space-time, and it does not take physics to see why. When it's midnight on Dec. 31, 2000 in L.A., Tokyo will already be well into the new millennium. You can't tell time without knowing where you are. And you can't know where you are unless you also know the time--because every second, everything in the universe (including us) is sweeping through space at breakneck speeds. Every millisecond, your position in space changes by miles.
There is no where without when.
"Stuff" is the only word to use when trying to describe unlikely matings like mind/brain, space/time, matter/energy. In fact, it's a good word to use for just about anything that has definite properties, but can't be easily defined. For example: Magnetic fields and forces. Mathematical objects, like prime numbers, or pi.
Emotions, ideas and poetry are stuff. Maybe that's why a chemist friend who also writes poetry freely sprinkles his writings with "stuff." He, too, has run into reluctant editors, who expect more from a Nobel laureate. He protests: "But it is stuff!"
The stuffiest of all sciences is a field called condensed matter physics--literally, the physics of stuff. It deals with liquids, glasses, metals, fluids, gases, ceramics--the crowd behavior of units of matter and energy congregating in space and time. Everything from sugar cubes to biological systems, miracle glue to human tissue, liquid helium to the structure of empty space. These days, it's where a lot of the most interesting research is taking place.
Even the stuff of dreams is coming from condensed matter these days: UC Berkeley's Marvin Cohen has dreamed up a new kind of stuff that's tougher than diamond. Various experimenters are now trying to condense his dream into concrete reality. It's very hard stuff.