Flash Forward Gets Schrödinger’s Cat a Little Wrong
Posted by Karl Withakay on October 29, 2009
Tonight’s episode of Flash Forward, “Scary Monsters and Super Creeps” contained a flawed portrayal of the Schrödinger’s Cat thought experiment (note the 2 separate links) in a conversation where a quantum physicist is trying to pick up a hot woman on a train by telling her he can explain what caused the flash forward. After mentioning that the most basic concept she needed to understand was quantum superpositions, they have some witty flirting and then the conversation proceeds as follows:
Physicist: “Imagine you have a cat, a teeny tiny cat that fits in the palm of your hand. You also have a poisonous sardine. Once we close your palm there are two possible scenarios: either the cat eats the sardine and dies or the cat doesn’t eat the sardine and lives. Quantum physics says until we open your hand to discover the cat’s fate, both eventualities occur at the same time. For us, the cat is both living and deceased.”
Hot Woman “But how can that be?”
Physicist: “That’s the miracle of quantum mechanics. The observer get to decide.”
The problem is that this thought experiment leaves out an important element of the original, a quantum probability. In the original experiment, the cat’s life or death is dependent not on a poisoned sardine, but on the potential decay of a radioactive isotope source. If the source decays and emits a decay particle, a hammer triggered by a Geiger counter breaks a vial of poison, killing the cat; otherwise the cat lives. The key is that the decay or non-decay of the isotope is a quantum probability, whereas the cat eating a poisoned sardine is not.
Schrödinger originated this thought experiment in an attempt to illustrate what he saw as a flaw in the Copenhagen interpretation of quantum mechanics. According to quantum mechanics, the cat is both alive and dead (because the isotope has both decayed and not decayed) until the observer collapses the quantum wave function by observing the state of the cat (which is dependent on the state of the isotope), even though common sense says the cat was obviously either dead or alive before being observed. The experiment also has nothing to do with the observer “deciding” anything. The act of observation collapses the quantum wave function to one state or the other, but no choice of states is involved or possible.
The Flash Forward thought experiment was an not an example of quantum superposition since no quantum state was involved, and it wasn’t Schrödinger’s/Schroedinger’s Cat.