Quantum Entanglement and the Misplaced Ghost of Einstein

Sabine Hossenfelder asks: did Einstein reject the idea of entanglement? The popular story says yes. The reality is more subtle: Einstein did not deny entanglement as a mathematical feature of quantum theory — he resisted the ontological claim that measurement instantaneously brings reality into being.

The confusion arises because two distinct issues were knotted together in the 1935 Einstein–Podolsky–Rosen paper:

1. The measurement problem — how a quantum system shifts from a potential spread of outcomes to a single observed value.

2. Entanglement — correlation between subsystems such that neither can be fully described in isolation.

Einstein’s critique was directed at (1), not at (2). He found it intolerable that observation itself should be construed as the event that actualises reality, especially if this “update” propagated instantaneously across spacelike separation. Entanglement was a device he and his co-authors used to sharpen the paradox of measurement.

From a relational ontology perspective, the problem is easy to diagnose: a slippage of strata.

• Theory: Quantum mechanics is a system — a structured potential for how particles may be construed.

• Experiment: Measurement protocols instantiate this system, cutting across entangled states to yield determinate values.

• Metaphor: “Spooky action at a distance” reimagines this cut as a physical influence, as if observation itself were a signal racing faster than light.

The last step is the mistake. There is no ghostly signal. There is construal. An entangled system is re-construed when measurement carves out one actualisation from the spread of possibilities. The correlation persists not because one particle “informs” the other, but because both are already positioned within a single systemic potential.

Einstein did not reject entanglement; he rejected conflating a systemic update in construal with a physical process in spacetime. His worry was ontological: that physicists were treating their own act of cutting as if it were the world’s own mysterious self-intervention.

The irony is that Einstein’s complaint remains alive today — not as a flaw in the mathematics, but as a persistent confusion in how we construe it.

So the sharper lesson is not “Einstein was wrong about entanglement” but:

The ghost in quantum mechanics is not action at a distance, but the category mistake of treating construal as if it were causation.