In 2004, C.S.Unnikrishnan of the Tata Institute of Fundamental Research in Mumbai, India proposed that the conservation law of angular momentum can correlate measurements of entangled electrons, explaining the perfect correlations of entangled particles, without the faster-than-light interactions-at-a-distance or "hidden viable" often invoked to explain nonlocaiity.

Unnikrishnan wrote

I derive the correlation function for a general theory of two-valued spin variables that satisfy the fundamental conservation law of angular momentum. The unique theory-independent correlation function is identical to the quantum mechanical correlation function. I prove that any theory of correlations of such discrete variables satisfying the fundamental conservation law of angular momentum violates the Bell’s inequalities. Taken together with the Bell’s theorem, this result has far reaching implications. No theory satisfying Einstein locality, reality in the EPR-Bell sense, and the validity of the conservation law can be constructed. Therefore, all local hidden variable theories are incompatible with fundamental symmetries and conservation laws. Bell’s inequalities can be obeyed only by violating a conservation law. The implications for experiments on Bell’s inequalities are obvious. The result provides new insight regarding entanglement, and its mea- sures

"Correlation functions, Bell’s inequalities and the fundamental conservation laws," arxive.org, 2004

In 2025, Unnikrishnan published "Information versus physicality: on the nature of the wave function of quantum mechanics., in which he wrote...

I derive the correlation function for a general theory of two-valued spin variables that satisfy the fundamental conservation law of angular momentum. The unique theory-independent correlation function is identical to the quantum mechanical correlation function. I prove that any theory of correlations of such discrete variables satisfying the fundamental conservation law of angular momentum violates the Bell’s inequalities. Taken together with the Bell’s theorem, this result has far reaching implications. No theory satisfying Einstein locality, reality in the EPR-Bell sense, and the validity of the conservation law can be constructed. Therefore, all local hidden variable theories are incompatible with fundamental symmetries and conservation laws. Bell’s inequalities can be obeyed only by violating a conservation law. The implications for experiments on Bell’s inequalities are obvious. The result provides new insight regarding entanglement, and its measures,

Unnikrishnan, C. S. "Information vs. Physicality: On the Nature of the Wavefunctions of Quantum Mechanics." Academia Quantum 2.2 (2025).

He also writes...

The question whether a wavefunction that represents a quantum physical state has an ontological existence in space and time (labelled an “ontic” state by some authors), or whether it represents merely the state of an observer’s knowledge about a physical state, and hence only of an “epistemic” status, has been debated since Schrödinger’s influential review paper in 1935 [1]. Schrödinger discussed in detail the difficulty of ascribing an ontological status to the wavefunction, forcing the “rejection of realism”, and he considered an interpretation of the wavefunction as “a catalogue of expectations”. In the initial era of quantum mechanics, there was a belief that a wavefunction had a physical existence, expressed as the wave-particle duality of matter. However, this belief waned quickly, because such an interpretation could not be maintained consistently, especially for multi-particle wavefunctions [1–3]. (The naive and inaccurate identification of the wavefunction with a real ‘matter-wave’ in space is still widespread, though).

The question whether a ψ-function is physically real or not is factually irrelevant for any calculation or quantitative prediction of the quantum theory, because the axioms of the theory as well as the well defined mathematical formalism to obtain the observable statistical results are entirely independent of this consideration [3, 4]. However, a physical understanding of the theory and a causal explanation of quantum phenomena are admittedly related to unravelling the nature of ψ-functions.

Unnikrishnan, C. S. "Information vs. Physicality: On the Nature of the Wavefunctions of Quantum Mechanics." Academia Quantum 2.2 (2025).

Unnikrishnan's references 3,4 are to John von Neumann and P.A.M.Dirac.

Another of Unnikrishnan's recent papers has shown that von Neumann's 1932 "impossibility proof" against "hidden variables" was not as mistaken as claimed by Grete Hermann and years later by John Bell.

Unnikrishnan's position that the wavefunction does not have a "physical existence" is consistent with our view that Ψ is pure information, providing precise knowledge about future experimental outcomes. The wave function is the mathematical solution of Erwin Schrödinger's wave equation. It allows us to calculate the values of physical quantities with extraordinary precision, unparalleled in other sciences.

But just how the immaterial wave can influence the positions of material particles remains a mystery, indeed what Richard Feynman famously called the only mystery in quantum mechanics. It's always the same phenomenon as the two-slit experiment, Feynman said, and there simply is no physical mechanism that can explain it.

Unnikrishnan says that the powerful idea of wave-particle duality misled many physicists to think the wave must be physical and material. He says "ψ-functions [are] an element for calculations and predictions, with no further assumption or speculation about underlying physical states that are totally irrelevant for quantitative quantum mechanical calculations." (Information vs. Physicality. p.4))

Long before Feynman, P.A.M.Dirac 's 1930 Principles of Quantum Mechanics cautioned newcomers to quantum theory (like me in the 1960's) not to imagine there would be classical mechanical explanations.

Nevertheless, the prominent physicist David Bohm in the 1950's proposed a fast-than-light quantum potential function whose gradient was the force that moves particles into the positions on the screen behind the open two slits. And some such "hidden variable" was at work in two-particle quantum entanglement, Bohm claimed. Followers of "Bohmian Mechanics" believe that the universe has been shown to be completely deterministic, as they think Albert Einstein really wanted (he didn't).

Returning to Unnikrishnan's strong defense of conservation principles. It is rarely argued that Einstein, Podolsky, and Rosen were using conservation of linear momentum to know instantly the position (or momentum) of the other particle when they measured the first particle, just as David Bohm in 1952 and John Bell in 1964.

In an important article written before Bell's Theorem paper, Eugene Wigner in 1963 cited the conservation of both linear momentum and angular momentum. Wigner wrote

If a measurement of the momentum of one of the particles is carried out — the possibility of this is never questioned — and gives the result p, the state vector of the other particle suddenly becomes a (slightly damped) plane wave with the momentum -p. This statement is synonymous with the statement that a measurement of the momentum of the second particle would give the result -p, as follows from the conservation law for linear momentum. The same conclusion can be arrived at also by a formal calculation of the possible results of a joint measurement of the momenta of the two particles.

One can go even further: instead of measuring the linear momentum of one particle, one can measure its angular momentum about a fixed axis. If this measurement yields the value mℏ, the state vector of the other particle suddenly becomes a cylindrical wave for which the same component of the angular momentum is -mℏ. This statement is again synonymous with the statement that a measurement of the said component of the angular momentum of the second particle certainly would give the value -mℏ. This can be inferred again from the conservation law of the angular momentum (which is zero for the two particles together) or by means of a formal analysis.

("The Problem of Measurement," in Wheeler and Zurek, Quantum Theory and Measurement, p,340)

Conservation laws are the consequence of extremely deep properties of nature that arise from simple considerations of symmetry. We regard these laws as "cosmological principles." Physical laws do not depend on the absolute place and time of experiments, nor their particular direction in space. Conservation of linear momentum depends on the translation invariance of physical systems, conservation of energy the independence of time, and conservation of angular momentum the invariance under rotations. Conservation laws are the consequence of symmetries, as explained by Emmy Noether.

The Bohm version of the EPR experiment starts with two electrons (or photons) prepared in an entangled state that is a mixture of two-particle states, each of which conserves the total angular momentum and, of course, conserves the linear momentum as in Einstein's original EPR example. This information about the linear and angular momenta is established by the initial state preparation.

Quantum mechanics describes the probability amplitude wave function Ψ₁₂ of the two-particle system as in a superposition of two-particle states. It is not a product of single-particle states, and there is no information about the identical indistinguishable electrons traveling along distinguishable paths. With slightly different notation, we can write equation (1) as

The probability amplitude wave function Ψ₁₂ travels away from the source (at the speed of light or less). Let's assume that at t₀ observer A finds an electron (e₁) with spin up.

At the time of this "first" measurement, by observer A or B, new information comes into existence telling us that the wave function Ψ₁₂ has "collapsed" into the state | 1₊2_- >
(or into | 1_-2₊ >). Just as in the two-slit experiment, probabilities have now become certainties, one possibility is now an actuality. If the first measurement finds a particular component of electron 1 spin is up, so the same spin component of entangled electron 2 must be down to conserve angular momentum.

And conservation of linear momentum tells us that at t₀ the second electron is equidistant from the source in the opposite direction. As with any wave-function "collapse", the probability amplitude information changes (it does not "travel" anywhere). Nothing really "collapses." Nothing is moving. Only information is changing.

If the measurement finds an electron (call it electron 1) as spin-up, then at that moment of new information creation, the two-particle wave function collapses to the state | + - > and electron 2 "jumps" into a spin-down state with probability unity (certainty). The results of observer B's measurement at the same or a later time t₁ is therefore determined to be spin down.

Notice that Einstein's intuition that the result seems already "determined" or "fixed" before the second measurement is in fact correct. The result is determined by the law of conservation of momentum.

Note the quantum mechanics claim that the particular spin values did not exist is also correct. Which of the two-particle quantum states | + - > or | - + > occurs is completely random. It is the result of "Nature's choice," as Paul Dirac described it.

Note also that before the measurement the two-particle wave function was rotationally symmetric, with no preferred angular direction. The preferred angle comes into existence as a result of what Werner Heisenberg called the "free choice" of the experimenter.

This choice of measurement angle breaks the rotational symmetry of the two-particle wave function. As Erwin Schrödinger described it to Einstein in his 1935 response to the EPR paper, the measurement disentangles the particles and projects the pure-state superposition into a mixed-state product of single-particle wave functions, either + - > or | - + >.

The joint property of conserved total spin zero is true for either + - > or | - + >.