I'm having trouble understanding the spooky action at a distance part. Two entangled particles are separated. The measurement of the spin of one immediately tells you the spin of the other. Since ngular momentum must be conserved, the spin of the two particles is opposite one another. Whats spooky about this? If you pull a right hand glove out of a box, isnt it reasonable to assume the second glove will be left? I feel like I'm missing something.

Too deep bro, need more info.

I don't understand much, but I think your assumption is incorrect.  The two particles are entangled, but I'm not aware that the sum of their angular momentum must be zero.  In other words they don't necessarily need to have opposite spins.  But maybe I'm wrong.

Your example, even if accurate (see other posts), doesn't show entanglement, as they could easily just have been created with those matching properties and went on their merry way.

For an example of action at a distance, consider a pair of photons, entangled with matching polarization (or not matching, but a known fixed relationship without having to be measured).  And then apply the wizardry of a series of polarizing filters.

In this experiment, we have three polarizing filters.  Starting with two filters, rotated by 90 degrees, they will stop any photon from passing, as a photon which passes through the first will be stopped by the second.  Now, add a third filter between the first, rotated so that it is 45 degrees from each.  A certain number of photons will now pass through the filter (the first weird part), showing that the center filter changed the orientation of photons which passed through the first filter.  All photons which make it through to the other side will have their polarization matching that of the last filter.  We haven't measured anything, but we know that the photon CANNOT have entered the filter setup with the polarization that it left, otherwise it would have been stopped by the first filter.  As a statistical property, we are fairly comfortable with the idea that a polarizing filter, if it passes a photon, will in effect set the polarization of the photon to match the filter, and that statistically the closer to "aligned," the more likely it is to pass.  Thus, some photons which passed the first filter make it through the second filter, and some that make it through the second filter likewise make it through the third filter, though if the second filter was not there none would pass.  This isn't all that spooky.

NOW measure the polarization of the entangled photon, and what will you find?  You will find that photons which passed through all filters have their entangled photons maintaining the relationship they had when they were created.  This is true even though classic physics tells us that the photon that passed through the filter does not have the polarization that it started with (if it did, it would have been stopped by the first filter).  This means that the entangled photon at some point changed its polarization, even though it passed through no filters.  THAT is action at a distance, because changes made to the first photon after the pair were created have affected the second without apparent interaction.  Also note that the effect is instantaneous, not bound by the speed of light.

Mike

Note - it must be pointed out that this DOES NOT enable instantaneous communication - you can't arbitrarily change the photon's orientation, only measure it to find out whether it is or is not oriented in a specific direction.  The act of measuring will set 50% to that orientation and 50% to the opposite (well, 90 degrees off, technically), but you have no control over which 50%, and at the other end, their test will do the same.  So someone looking at an entangled photon at the other end will be able to determine its polarization, but NOT whether that is due to the original being changed or simply having always been that way.  Entanglement is "broken" at the first measurement, so any changes after that will not be reflected at the other end.

Think of it this way, think of the Schrödinger’s cat experiment, now put them on two different universe, the entanglement comes from the moment one cat is determined to be alive or dead, there is a faster than speed of light connection to the can in the other universe that determines wheather it’s live or dead.  One problem is traveling faster than speed of light for this phenomenon to be true!

Computationally you can actually calculate the conflict.  IIRC, there’s a good video on YouTube about this.

https://youtu.be/ZuvK-od647c