Entrophy and the teenage mind
Dr. Maureen Hunter | TLT From the Editor April 2009
Apparently the Second Law of Thermodynamics explains why my daughter can’t clean her room.
‘The higher the entropy of this room, the higher my grade,’ she said.
The English scientist and novelist C.P. Snow once said that the Second Law of Thermodynamics was the scientific equivalent of Shakespeare’s Hamlet.
So what is the Second Law of Thermodynamics? For me, I just think of my teenage daughter’s room.
“Don’t tell me there’s food in here again and you’re conducting another so-called biology experiment,” I said, eyeing a half-eaten sandwich left on the desk in her bedroom.
“No, no, we’re done with biology. Had the exam yesterday.”
“Good!” I said. “Now you have time to clean your messy room.”
“Can’t do.”
“Why not?”
“Now we’re studying the Second Law of Thermodynamics,” she answered. “Entropy, Mom. You know—the tendency of systems to become messier quite spontaneously in spite of everything you do. I’m conducting research for a homework assignment. I call it the entropic room experiment.”
“The entropic room experiment?” I questioned.
“Oh, yes,” she said, handing me a graded school report. I looked down at the report. It read, “Very clever, A+.”
“I’m using my bedroom as a large-scale model,” she continued. “My books, my papers—everything in here represents atoms and molecules.”
“I can see your experiment includes dirty and clean clothes, too! Pick them up.”
“But, Mom, we’re studying closed systems. No energy input allowed.”
Just then a lone paper slipped off a corner of her desk that was buried under two feet of school debris.
“Ah, an increase in entropy already,” she said. “Thanks, Mom, for always encouraging me to study science. In a closed system, entropy can never decrease. And the higher the entropy of this room, the higher my grade.”
“Just do your report on how heat tends to diffuse evenly and that it flows from hot to cold,” I said.
“The second law reaches far beyond the concept of heat,” she said. “In its most general form the second law comments on the state of order of the entire universe. I don’t mean to be rude, Mom, but seriously, just look in the mirror at those crow’s feet to see entropy in action.”
“I’m beginning to like this law less and less,” I said. “Please clean your room.”
“But, Mom, a clean room is boring. Just think of it—entropy is a measurement of its disorder. It’s the logarithm of the number of different possible ways you can achieve a particular configuration. There are so many more ways to achieve a disordered state than an ordered one. The second law offers more possibilities in life.”
“Hmm,” I said.
“The second law is one of the most profound laws in science with consequences far beyond your crow’s feet. It dictates the very direction of time. Of all the great laws of nature, only the second law of thermodynamics incorporates the arrow of time.”
“Laura,” I said. “In your scientific career you’ll learn that the laws of arguing with your parents are just like the laws of thermodynamics—the first law states that you can’t win, the second law states that you can’t even break even. So pick up your room and work on an experiment that violates the second law, because any violation of it, however small, would solve the world’s energy problems and earn you a trip to Stockholm to accept the Nobel Prize.”
Maureen Hunter is technical service manager for King Industries in Norwalk, Conn. You can reach her at mhunter@kingindustries.com.