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Physics at Princeton

The Lemonick and Woggy Show

What follows is my attempt to reanimate the anything-goes nature of physics at Princeton in 1966-67.
   - Jack Ritter, class of '70.

In 1966, I was a freshman physics major at Princeton. Our introduction to college physics was provided by the esteemed Professor Aaron Lemonick, who went on to become dean of the Graduate School in 1969. His lectures were notorious and unforgettable, due in part to the demonstrations that brought them to life. The man who created these demonstrations was the perfect lecture assistant. His name was Mr. Woggy ('Wah Gee'.)

Lectures took place in a large hall with built-in wooden seats which rose to great heights in back, like a stadium. You could sit above Lemonick, but you couldn't hide from him. The place resonated with his deep voice. Giant rolling chalkboard panels were stacked stage left, one behind another, like a deck of cards.

He'd fill one with sweeping equations, then giant windmill arms would send it out of sight, and roll in another. After he'd filled them all, previous equations would be rolled out again, to be annihilated by his two foot eraser. Finally he would say something like, "And now my assistant Mr. Woggy will demonstrate this principle." Mr. Woggy was slightly built, never spoke, and moved deftly. (I think he wore a hat.)

Lecture 1: The Inverse-square Nature of Gravity

Woggy comes out and attends to gadgetry, as Lemonick narrates: "My Woggy has simulated the inverse-square effect of gravity with a vacuum cleaner that tries to suck in a ping pong ball attached to a string. The other end of the string goes up through a hole in the center of this smooth metal table, and attaches to our CO2 puck."

The CO2 puck, a recurrent woggyism, was like a smooth metal hockey puck, with tiny holes drilled into its underside. A piece of dry ice was put into its hollow center, then sealed off. As it evaporated, CO2 poured out through the holes. This made the puck float on a layer of gas, and glide "frictionlessly." (This was before Air Hockey.)

The end of the vacuum cleaner was a narrowing cone. As the ball was sucked into it, the string pulled the puck toward the hole in the table. As the ball was pulled into the narrowing channel, it took up an increasing percentage of the cross sectional air flow. In addition, the air pulling on it was travelling faster. The compounding of these two effects caused the ball to tug on the string with a force proportional to the square of the distance it moved. Correspondingly, the distance between the hole and the puck decreased. Thus, an inverse-square force was born.

Lemonick pushed the puck, and it fell into an elliptical orbit, just like a planet around the sun. He could make eccentric orbits, with the puck really whipping around the hole at the close end, or he could make steady circular orbits. It got applause.

Lecture 2: Super Conductivity and Electromagnetism

"Mr. Woggy has provided us with a vertical electromagnet, and a metal hoop that fits around it like a collar." He set the hoop down, at the bottom end of the electromagnet, then turned it on. The hoop jumped up six inches, then fell back down. "When I turned it on, the increasing magnetic field induced an accelerating circular current in the hoop, which momentarily forced it upward. Now let's see what happens when I turn the hoop into a superconductor."

He placed the hoop in a little container, poured liquid nitrogen over it, and placed the hoop back on the magnet, using tongs. He turned the electromagnet on again. This time the hoop shot off of the magnet, flew thirty feet into the air, and disappeared into a hole in the ceiling. A rubber chicken fell back down. More applause.

Lecture 3: Elastic Collisions among Mixed Gas Molecules

"This time we have lots of little CO2 pucks. Some have more mass than others. They will float on the same flat table, which is walled off at the edges to form a coral. Mr. Woggy has retrofitted the pucks with steel bumpers, so they can bounce off of one another, as well as off of the containing walls." It was the two dimensional analog of a mixed gas. The heavy pucks represented the more massive molecules. The pucks floated around slowly.

He gave one a push. It hit others, which hit others. This chain reaction soon led to boxed-in chaos. Each puck bounced continuously off others. The heavy ones muscled through the crowd, suffering minor deflections. The light ones ricocheted around like helpless BB's. The whole thing was so elastic and frictionless it could have continued forever, it seemed. Even more inspiring was the one dimensional case: upside down, V-shaped pucks hovering on top of a triangular rail. It looked like the inside of a plugged up machine gun.

Lecture 4: Damped Oscillation and the Heart

"Damped oscillation is everywhere, even in our blood. When the heart contracts, the thrust of the blood going out causes the heart to jump in the opposite direction. The surrounding muscles then send it back, with a little push. And so on. The combined momentum of this, plus the blood itself, has a net effect on the body."

Two metal rods had been laid on top of a perfectly horizontal table. A long plank rested on top of the rods, which acted as rollers. "Now I need one of you to volunteer. To come down here and lie on this board." Some guy did. There was a small mirror glued to one of the rollers. A laser was aimed at the mirror. The reflected beam went way up to the ceiling.

"The movement of the board is being amplified by the reflected beam. Look up there." The blurry red dot of light moved back and forth, then settled on a spot in the middle. This sequence repeated continuously. It was like a visual stethoscope. I recall another phenomenon nearly as remarkable: his pulse was normal.

Maybe my recall of all this seems suspicious. My explanation is this: I have periodically recounted these four stories to anyone who would listen, keeping their memories refreshed.

Each one closely follows a well-known principle. If you love physics and you remember an equation, you tend to remember the first time you saw that equation get up and walk. These memories are steeped in fondness as well, thanks to a waving bear of a man, Professor Aaron Lemonick, and his accomplice, the wily Mr. Woggy.

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