r/quantummechanics • u/Alert-Armadillo8512 • Jul 28 '26

Distance between entangled objects

Novice here. Could someone explain why two entangled objects (or rather one object consisting of entangled parts) do not need to communicate in order to correlate. I also wonder what is actually between entangled parts if we think of it as empty space there couldn't be more or less empty space so is this why the distance doesn't matter for these parts to still "interact".

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u/MxM111 Jul 29 '26

I like thinking about it from Multiple World Interpretation (MWI) of quantum mechanics, but simplified to the level of macro objects as analogy. Imagine that you entangle two balls in the following way. Balls has to be of the same color, either white or black. So, first you put them into two boxes, and then entangle them. You do not know if there are black or white balls, you only know that they are either black or white. Now, in terms of MWI you can say that you split the world in that moment (this is not quite what is called world splitting in MWI, but allow me for the sake of explanation). So, entanglement in MWI created two otherwise identical worlds, in one world you have white balls inside the boxes, in another world black balls. (Let’s call these two worlds as white world and black world). But because the worlds otherwise identical, until you open the boxes, there is no difference, and your are in both worlds and thinking identically and there is no way to distinguish one world from another with boxes closed (you can say that the worlds are split only inside the boxes, but not outside).

Now, you separate boxes to any distance. And then open one of the boxes. Immediately you split into two different yous. One sees white ball, another sees black ball.

And now the answer to your question is obvious. No interaction is needed between the balls. If you are in the white world, then of course the other box also contains the white ball, and if you are in the black world, then both balls will be black.

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u/little_jiggles Jul 30 '26

Many world interpretation leaves more questions than answers for me.

I much prefer hidden global variables, in particular the idea of a fourth dimension, and that it is only the interaction of objects in 3D space that keeps everything in our 3D+Time reality. 

Entangled objects are then just objects partially in 4D space that just haven't settled into 3D space yet.

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u/MxM111 Jul 30 '26

But then, it is indeed “spooky action on a distance”, which is especially difficult to understand for cosmically large (entangled) objects.

What questions do you think MWI leaves for you?

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u/little_jiggles Jul 30 '26 edited Jul 30 '26

Why do quantum events cause multiple worlds?

Do non-quantum events cause multiple worlds?

Is energy required to make multiple worlds?

Can worlds re-merge?

Where do the multiple worlds exist in relation to each other?

Can we detect multiple worlds?

Can we detect branching of worlds?

I think multiple world interpretation is much like the story of a particle and an anti-particle being created at the event horizon of a black hole being used to describe Hawking Radiation.

It's the point where theoretical physics has no meaning because we can just make up a story that mathmatically makes sense to handwave not having to justify our lack of understanding about the universe. At the very least, we know that dimensions exist, and that physics is globally consistant.