The experiment, described in a paper published in 2024 in Physical Review Letters,, harks back to a conundrum vividly framed nearly a century ago by Erwin Schrödinger, one of the founders of quantum mechanics. What would happen, Schrödinger asked, to a cat trapped in a closed box with a vial of poison that has a 50-50 chance of shattering and killing the cat? According to quantum mechanics, the cat is at once alive and dead, existing in both states until someone looks inside the box. That’s because according to quantum theory, it’s only when an observer makes a measurement of the system—opens the box and checks—that the two possibilities have to collapse into one. The story is meant to illustrate how applying these quantum rules to big things—basically, anything visible to the naked eye—leads to absurdities.