I have read many attempts to explain quantum entanglement and “spooky action at a distance.” I’ve studied stage magic tricks, so I get used to asking, “How could that have been accomplished without magic?” All of the analogies I’ve read leave holes that allow the effect but require absolutely no unexplainable infinite-distance phenomena. I do believe physicists who tell me, “Trust me, if you knew the math, you’d think this was really weird.” I want to understand better, so instead of asking you to present yet another lesson-by-analogy of quantum mechanics, I’d like to present an analogy and ask you some questions along the way in order to rule out various “cheats” that physics might be using. This will give me an understanding of exactly where the mystery of quantum mechanics lies. I hope you don’t mind my presumption that you’ll take the time to answer.
So, here I go…
Quantum mechanics (QM) says you take two particles, entangle them such that some attribute is simultaneously in multiple states, then separate them by an arbitrary distance. When you measure one of them to ask what the attribute’s actual value is, you can measure the other one at the same moment and the measurement will agree, even if there’s a greater-than-light-speed gap between the two particles at the time the measurements are taken. The spooky action is the “communication” of that measurement between the two particles, faster than light.
The analogy runs like this: I have a bunch of gloves. I pick two of them and then entangle them such that both gloves are simultaneously left-hand and right-hand gloves.
That brings me to the first question…
- A lot of magic tricks are solved by a magician’s force right up front. Can I really pick any two particles and entangle them? Or when I get an entangled pair, are they possibly connected for me already? In other words, am I some how tricked such that every time I get an entangled pair of gloves, both gloves are secretly already right-hand gloves but superposition makes it impossible for me to see whether they are both right or both left? This would be akin to asking the audience to showing the audience a deck of black and red cards, then secretly swapping the deck for one that is all red cards and asking them to pick two, then putting the two in front of a flashing blue light — when the light is on, the card looks black; when the light is off, the card looks red, but it is always actually red. Do I really have a free choice of particles?
Ok, assume I really can pick any two particles. Now I entangle them and put them in separate boxes. Let’s call them particle Alice and particle Bob. Or, for the gloves, glove Alice and glove Bob.
What does it mean to entangle them? If this were a stage magic trick, I’d say, “The magician just made both gloves be right-hand gloves just now and then put them each into a box.” The magic would be reshaping the gloves, but that doesn’t require any spooky action at a distance, just some slight-of-hand tailoring… all local effect. If we cannot measure the particles, that means there must be something that we can do with an entangled particle that we cannot do with an unentangled particle. What evidence makes us believe that two particles are actually in superposition when entangled? Put another way, how does the superposition particle’s interaction with the world change?
Now, assuming that the two particles/gloves really are simultaneously in two states, it might be that one state is tagged somehow such that the particles when measured will always be the same. Going back to the deck of cards earlier, if both cards become “really red” when entangled but only look like superposition, then when they stop being in superposition, both cards will be red. No surprise there, and no spooky action at a distance. Do we know there’s no pre-decided state for the particles to settle in? (How do physicists prove that negative?)
Now I give one box to my lab partner and take one box for myself. My partner and I synchronize our clocks and start a 1 year countdown timer. Then we get on space ships and fly away from each other at the same (very high) rate. With my really good telescope, I see my partner’s clock slowing down as we get further apart (time dilation).
- When my countdown clock reaches 6 months, is there anything I can measure to assure myself that the particle is still entangled? This is similar to question 2, but instead of talking about the pair, I’m now asking about the lone particle. If I can’t test that the individual particle is still entangled, how do I know that the decision wasn’t made as soon as the two particles were put into their respective boxes (or made as soon as the particles reached some light-cone distance from each other)?
At last, my clock hits zero. I open my box. I see a right-hand glove. Nothing magical about that assuming all the previous questions ruled out a pre-decided state and it really was in both positions, it could have been either one. It just happened to be right. In my telescope, I see my lab partner still not yet having opened his box… it’ll be a while before I see that event. So I turn my space ship around and fly back to the origin point.
My lab partner opens his box when his countdown reaches zero. In his box, he finds a right glove. He is unsurprised, just as I was. He also looks through his telescope and sees me still waiting to open my box (time dilation works both ways). He also turns his ship around and flies back to the origin.
We meet up. We report are results. And we are impressed to find that we both got right hand gloves.
We repeat the experiment 10,000 times. 1 million times. Every time, the gloves match. Now we are really impressed, and we think, “Wow. Somehow the gloves are communicating.”
So, in summary…
Do I know the particles are freely chosen? Can I verify entanglement without breaking entanglement? Can I rule out pre-assigned bias of the state when entanglement breaks? If so, then I agree quantum mechanics is weird. If not, then I’m curious why other people think QM is weird.