EdObserver

If you’re not a physicist, trying to understand the Shrödinger’s Cat paradox can make your head spin. Don’t feel too bad, though, because 80 years ago, more or less, the Schroedinger’s Cat paradox made the heads of the most brilliant minds in physics spin!

One of the simplest explanations of the paradox has been provided by John H. Lienhard as part of the University of Houston College of Engineering’s “The Engines of Our Ingenuity” series.

Professor Lienhard starts out quoting a remark by physicist Abner Shimony:

“Physical systems cannot be said to have definite properties independent of our observations.”

What Shimony is doing here is giving a simple description of a thought experiment that’s come to be known as “Shrödinger’s Cat.”  The Cat is “a creature born in the strange new thinking of quantum mechanics,” observes Lienhard. But the concept of Shrödinger’s Cat has implications for everyday life, not just quantum mechanics.

“The riddle of the cat begins with Heisenberg’s uncertainty idea,” says Lienhard, continuing, “the most precise measurement we could ever make would be to shoot one photon of light at a moving object. But even so delicate a peek will change the position and motion we’re trying to measure. …

“Schrödinger said that if that’s the case, let’s seal a cat, a geiger counter, a fragment of radioactive material, and a bottle of poison gas into a box for one hour. There’s a 50-50 chance that radioactive decay will trigger the geiger counter, activate a mechanism that breaks the bottle, and poison the cat. He asks if we’ll find a live cat or a dead one when we open the box.

“That sounds like the “Lady or the Tiger,” but it’s much worse. The man who has to open either of two doors knows a lady is behind one and a killer tiger behind the other. He doesn’t know which door leads to the tiger, but the answer is knowable. Radioactive decay occurs on the level of indeterminancy. No knowledge of the system inside the box will ever let you predict the fate of Schrödinger’s Cat. Whether it lives or dies is absolutely unknowable — until you open the box.

“Physicists agonize while that Cheshire cat sits and smiles.” Steven Hawking, the physicist who writes about black holes from his wheelchair, throws up his hands and cries: “When I hear of Schrödinger’s Cat, I reach for my gun.”

Cartoon by Nick D. Kim, lab-initio.com. Used by permission.

“But in the end we have to look inside the box to learn whether the cat is alive or dead. So it is that the observer determines the truth [emphasis added].”

You can read Prof. Lienhard’s entire discussion of Shrödinger’s Cat on the University of Houston’s website, or listen to it, courtesy of the Friends of KUHF in Houston. If you want to learn more about the atom, quantum mechanics and Heisenberg’s uncertainty principle, you can watch the short YouTube video. A straight-forward statement of the uncertainty principle, by Michio Kaku of CCNY, comes about five minutes into the video.

To get the full impact of how the Schrödinger’s Cat paradox can affect human interactions, you might want to watch “The Tangerine Factor” episode of CBS’ comedy series, “The Big Bang Theory.” Sorry, but we can’t provide a direct link.