According to physics lore, it was Albert Einstein who coined the term “spooky action at a distance” as perjoritive description to be applied to systems which seemed to exhibit behaviors that were not explainable by direct causal means.
Direct causal means?
For example. Imagine you’re standing up holding a bright red rubber ball at arm’s length in front of you. What would happen if you let go of the ball? It would fall down, right? Here’s the odd question. How does the ball know which way is down? The ball doesn’t have eyes, it can’t tell where the ground is. It’s spooky if you think about it.
Imagine the same ball dropped into a moving stream. The ball will immediately begin to move downstream. How does the ball know? It knows because the water molecules in the current push on it from one side and move away on another. The ball’s motion is a reaction to the environment.
So, again, how does the ball know which way to go? Supposedly according to Newton, the ball will fall toward the center-of-mass of the earth/ball system. But how does the ball know? How does the center-of-mass tell the ball? It’s spooky action at a distance!
Einstein’s theory of General relativity effectively explains this behavior by noting that time runs slower as we move deeper into a gravity well. So, it’s not that the ball knows where the center-of-mass is. But it can tell that on one side of the ball time is running slower than on the other side. And apparently, according to the way Einstein’s field equations work, objects move in a direction that causes them to experience slower time.
So that’s all well and good. It explains in a direct sort of causal way why a ball falls down. It’s the kind of causal deterministic answer that classical physics expects to always be able to find. And that’s why classically convinced physicists have issues with the spooky-action-at-a-distance of quantum physics, particularly in the situation where two or more particles have their wave functions entangled.
But perhaps people have argued, it might only be that this sort of quantum non-local, non-causal behavior occurs only in the situation of entanglement. If that’s the case, then yes, perhaps it’s weird, but it might eventually be explainable, and we’ll all end up back in nice rational land.
So, a group of physicists in Austria decided to see if they could observe quantum vs. classical behavior in the simplest system imaginable. A single massless photon.
” The physicists used a “qutrit” – a quantum system consisting of a single photon that can assume three distinguishable states. “We were able to demonstrate experimentally that quantum mechanical measurements cannot be interpreted in a classical way even when no entanglement is involved,” Radek Lapkiewicz explains. The findings relate to the theoretical predictions by John Stewart Bell, Simon B. Kochen, and Ernst Specker.
Quantum physics is in stark contrast with what we perceive and experience in our everyday lives and what we understand as “classical physics”. Let us, for example, examine a globe: from a given point of view we can only see one respective hemisphere at any given time. When spinning the globe once around its axis we are able to construct a meaningful and “true” picture of our planet assuming that the shape of the continents stays the same, even when we cannot see them.
Therefore, by means of our experience and the assumptions made in classical physics, we can assign certain properties to a system without actually observing it. This is no longer the case if one pictures a “quantum globe”. Contrary to a globe where –due to the assumptions of classical properties– the various pieces fit together as they do in a puzzle, the pictures of the quantum globe do not fit together. Yet the pattern is not random: it is possible to predict by how much the individual parts will differ from each other after an observation.”
What does this mean? At one level it’s confirmation of a long series of experiments stretching back into the 1970’s that have again and again demonstrated that quantum behavior is a fundamental quality of small scale physics. It can’t be explained away and it can’t be placed into a classical container. It just can’t.
And that means that binary world-views of yes and/or no don’t apply in certain situations.
But binary world-views do apply in others. Like at our length scale as humans.
Complicated world. One rule does not fit all.
I suppose at the very least we need to draw the conclusion that the reality we experience is not ultimately capable of being reduced to a simple explanation. I liked reductionism. But apparently the Universe has discounted my vote.
So there we are. We are going to have to recognize that simple answers won’t work in all cases.
Sort of sounds like the basic dictum of Anglican Moral Theology. “Circumstances alter cases.”
More on that later.