Quantum Mechanics for Poets

I was invited to run an experiment in a science fiction elective class today, because students are reading a story by Greg Bear called “Schrodinger’s Plague”, about a group of physicists who fear that they’ve been exposed to a deadly virus. The story hinges on a parallel with the Schrodinger’s Cat paradox/thought experiment, so I wanted to give students an appreciation for what we were actually dealing with here…

I showed them a two slit interference demo, then contrasted this with what we’d expect to see if we shined light through two slits. We defined these observations as “wavish” and “non-wavish” behavior, respectively.

Then we did an experiment with a coin and two cups (not these, the ones we used had tops on them). I put a coin in one of the cups, and then mixed up the cups so that no one knew which cup had the coin. Two “carriers” then took the two cups on separate paths, carefully, so as not to reveal the path of the coin. When they got to their destination, the teacher of the course mixed the two cups again, and then a “screen” checked to make sure that the coin arrived.

This experiment, we said, caused a “wavish” pattern.

We then did the experiment two more times. In the next run, a “detector” on both sides took the cup and shook it, so everyone knew which cup held the coin. The third time, however, the detector just peeked under the lid of the cup, revealing to no one else what they saw.

We agreed that the first of these latter experiments would cause a “non-wavish” pattern, but the third one tripped people up a bit. Who did the detector represent? Did it matter? Is it possible for the an individual person’s perception of the pattern to change, depending on what they knew?

Physics has solid answers to these questions, and I revealed them eventually, but it was cool to hear the students arguing about what made the most sense. As science teachers, I think we sometimes take for granted that students approach this work with the same empiricism that we do. But to these students, the idea that a pattern might change to something else when someone whispered information in your ear wasn’t so far fetched!

##modern ##physics ##interdisciplinary

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