High Energy Physics was long completely isolated from foundational questions of Quantum Physics. The quip of HEP physicists was:”Shut up and calculate!”… instead of worrying about entanglement, nonlocality and the ultimate mature of reality. Well, this has now changed, big time. For the first time, quantum entanglement was used to probe gluon geometry inside nuclei. Gluon, which are bosns, have “color” hold the quarks together inside hadrons, but it turns out they can come out a bit. [1]

*The STAR detector, itself about the size of a house, is the first detector sensitive enough to measure the entangled properties of the daughter particles arising from a relativistic heavy ion “near-miss” interaction. This early 2023 result is the first to demonstrate entanglement between two non-identical particles.* (Credit: Brookhaven National Laboratory)

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Many will find baffling that matter waves from different types of particles can be antangled. Here is my take on it:

Careful considerations show that **quantum physics is obtained by simplifying the facts and logic of classical mechanics as much as possible** (*warning: textbooks often say the opposite… without proof!*)

Consider for example spin. Instead of an arbitrary angular momentum axis for each of two entangled particles, as classical mechanics has it, consider just one axis… for both particles, at the same time! And instead of continuous angular momentum, reduce angular momentum to just two values (+ or -)… for that one axis! Out of that most simplified description, this barebone reality, nonlocal entanglement of spin (photon polarization or silver atoms…), or **nonlocal entanglement of two states systems in general, is obvious… being germane to the most simplified, aka, “quantum”, description of the system.**

The spaces one gets that way, by simplifying the classical descriptions, “quantizing” them, often with discrete outcomes, have as basis the quantum outcomes (“states”). To compute therein, use the simplest math: complex numbers and linear algebra operating on amplitude waves. As evolution equations, use the simplest partial differential equations, where evolution is driven by energy. And so on.

Simplifying to the max a barebone description of the electron with the simplest amplitude wave is how Dirac got his equation, out of which popped antimatter, and precise measurements…

The **metalogic of quantum mechanics as the simplest description of classical mechanics extends throughout… As long as one is willing to generalize the notion of space (for example electrons live in 4 dimensional complex space).**

In other words, far from weird, quantum physics is exactly what you would expect by making the simplest parody of reality that one can still compute with. Nonlocality pops out naturally, as soon as one realizes that many “particles” can be entangled in one outcome. That the “particles” are of different nature is besides the point… and now we have the experimental proof of that! Classical mechanics did not forbid nonlocality of quantum amplitudes, but the simplest-description axiomatics obtained by simplifying classical mechanics to the max, required it..

**A spacetime foam has been evoked by relativists as the ultimate nature of reality. Now high energy physics is revealing its nature: inter alia, quantum amplitudes are transferred from one type of particle to another, in the EPR, nonlocal way.** Quantum Physics happens in Quantum Spaces (aka “phase space”) spanned by Quantum Outcomes (“Quantum states”).** Local, classical reality is a statistical effect from a hidden thermodynamics of nonlocal entanglement.**

Patrice Ayme

Reference:** Tomography of ultrarelativistic nuclei with polarized photon-gluon collisions**

“*We measure two outgoing particles and clearly their charges are different – they are different particles – but we see interference patterns that indicate these particles are entangled, or in sync with one another, even though they are distinguishable particles,*” said Zhangbu Xu, a (Chinese) author of the study (this was a very multinational collaboration).

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[1] Gluons do not interact with photons directly, because photons don’t have color. But a photon can transform in an ephemeral quark-antiquark pair, which will interact with the gluon. Ultimately the inner geometry is revealed by the outgoing entangled yet distinguishable pions (with opposite electric charges!)