Spooky Action

Imagine throwing a pickle across the room you’re in right now.

You shake any extra vinegar away from that dill-marinated cucumber before lobbing it at the wall. Splat!

If it’s soft enough, some of the pickle will stick to the wall, but if it’s hard enough, it’ll bounce off entirely, landing on the floor several pickles away from the wall.

This is how things generally seem to work to us: we do something over here, and then something happens over there. This is so intuitive to us that it seems silly to even describe what happens to our sandwich flavor-bomb.

We are wired to understand the world at this scale. Think of all the times our forebears must have had to dodge quickly in order to avoid certain death, and you can see why we’ve evolved to be so focused on things around the same size as us.

At the smallest scales of nature, things are… well, different.

Unlike our pickle, the quantum realm offers us a notion called entanglement. This means that the two particles (or objects) can influence one another instantly, with no delay between action and reaction, or between cause and effect.

When two objects are in this state, they behave in a manner that seems more like magic than reality to us. It’s as though you flip a coin over here and get heads, so you know that a coin on Mercury is now showing tails, and vice versa. You know this state instantly with this idea of entanglement.

Einstein hated this so much.

This went against the idea of an orderly, predictable universe where one thing clearly caused another thing to happen. This hesitance might seem a bit incongruous for the guy who first pointed out that there is no such thing as “at the same time,” but Einstein had his reasons.

For starters, there was locality. The principle is that any object can only be affected by its immediate surroundings. In other words, the pickle goes splat when it finally reaches the wall, but not instantaneously when you throw it.

Normally, light speed is the ultimate limiting factor in the universe. Time and space bend around this constant speed, and nothing can go any faster than this speed, c. When something happens over there at the same time as it happens over here, this seems to violate this principle in particular, something utterly central to the idea of relativity.

We prove the usefulness of constant light speed every day when we use GPS-enabled technology, which counts on light’s constant speed in order to determine precisely where something is, for these satellites truly only measure the time a signal takes to return. They already know the speed of the signal, so the time tells you exactly how far away the thing is.

Einstein called the phenomenon he hated so much spooky action at a distance. This shows a surprising mastery of language for a physicist—physicists are famously very bad with naming things. Calling it spooky invoked the supernatural, implying that the action was anything but natural.

Pointing out that this action was at a distance called attention to Einstein’s central objection, that light could not convey information instantaneously.

Quantum mechanics seemed utterly counter to human intuition, and even seemed to violate basic logical principles. The very idea that nothing existed until you looked at it bothered him intensely. Schrödinger's cat was intended to point out the absurdity of the notion that a particle can be in two states at the same time, claiming that there’s no way a cat inside a box could be simultaneously alive and dead. 

Instead, many physicists worked hard to describe wave-function collapse by invoking more comprehensive theories like QFT (Quantum Field Theory) and eventually RQM (Relational Quantum Mechanics), offering explanations that make logical (if not intuitive) sense. For those interested in diving deeper into QFT or RQM, feel free to join the discussion in the comments:

Even worse for Einstein, entanglement has been proven experimentally. Not only have tiny photons been entangled, but so have actual molecules. Entangling multiple sets of atoms means that lots of different particles are simultaneously in the same quantum state, and this is a notable and impressive feat.

Could this spooky action represent a new paradigm for us in technological development? Perhaps one day, but for now, we are steadily refining our understanding of how entanglement works, running ever more sophisticated experiments to test the limitations and to better grasp how it all works.

I’ll tip my hat to Einstein once more for his excellent naming convention, and offer my deepest sympathies for having to concede that spooky action really does happen at a distance.