The thing that's "spooky" about quantum mechanics is that it is NOT just infinitesimal forces causing precision to be impossible. That's more chaos than quantu

The thing that's "spooky" about quantum mechanics is that it is NOT just infinitesimal forces causing precision to be impossible. That's more chaos than quantum. Here's a bit from my own research. I start with a neutron whose spin is pointed up. I then use magnets to bend the neutron's trajectory depending on whether it's spinning to the left or the right. Since the spinning in the up state is a linear combination of spinning in the left or right states, it just so happens that I don't know whether the neutron bends to the left or the right. For most of the neutrons, that's all I do. Another set of magnets pulls the beams back together. They get to the end of the instrument and I measure whether they're spinning up. Since I haven't done anything besides split the beam, they're all still spinning up. However, for a small fraction of the neutrons, I measure which way they bent. I know know whether it is spinning left or spinning right. Let's say it's spinning left. Well, just as spinning up is a linear combination of spinning left and right, spinning left is a linear combination of spinning up and down. Since I know that the beam is spinning left, I no longer know whether it's spinning up or down. When I measure this neutron at the end of the instrument, it only has a fifty percent chance of pointing up. This isn't a couple of photons hitting a particle and changing the velocity slightly. I've gone from all of my neutrons pointing up to only half of them pointing up. You might immediately assume that the problem is that I did something to the neutron when I measured whether it was pointing left or right. The "spooky" thing about this is that I didn't do a single thing to that neutron to measure which way it was spinning. The way I perform the measurement is that, after I split the neutron beam, I put a wall in one of the beams. The other path, however, is just the same as it was before. I haven't touched any of these neutrons. Each of these neutrons goes through the exact same fields and paths as they did in the experiment where all the neutrons were pointed up, except no half of them are pointed down. Quantum mechanics doesn't just say that you have to touch something to measure it and that will effect the outcome. It says that performing a measurement will effect the outcome, even if you don't touch it. That's where some people get spooked. ---- To preemptively answer a couple of questions: 1) No, you can't use magnets to bend neutron beams based on the Lorentz force. However, the neutron does have a magnetic moment which produces a potential with a magnetic field. This leads to an index of refraction change that causes a slight angular splitting of the neutron beam. Nothing ever gets separated by more than a micron. 2) No, I don't really put in a wall to measure just the left spinning neutrons. There's a solid material whose density fluctuations over the micro length scale serve as my effective wall. Thus, I don't actually get half the neutrons flipping at the end of the experiment, but rather a fraction proportional to how much information I get about the left right spin from my single wall.