Let’s break down these two interpretations of quantum mechanics — both offer deterministic alternatives to the standard probabilistic view, but they do so in very different ways:

Bohmian Mechanics (Pilot-Wave Theory)

• Core Idea: Particles always have definite positions and velocities. They’re guided by a “pilot wave” — which is just the wavefunction evolving according to Schrödinger’s equation.

• Wavefunction: It’s real and governs the motion of particles, but it doesn’t collapse.

• Randomness: It’s epistemic, meaning it arises from our ignorance of the exact initial conditions — not from any fundamental indeterminacy.

• Measurement: No mystery — the particle was always somewhere; we just didn’t know where.

• Pros:

  • Fully deterministic.

  • Solves the measurement problem without collapse or branching universes.

• Cons:

  • Requires nonlocality (instantaneous influences across space).

  • Hard to reconcile with relativity.

Superdeterminism

• Core Idea: Everything — including your choice of what to measure — is predetermined. There’s no true “free choice” in experiments.

• Wavefunction: May be real or epistemic, depending on the variant, but the key is that all outcomes are fixed.

• Randomness: Entirely illusory. Even apparent quantum randomness is just a reflection of our ignorance of the full causal chain.

• Measurement: The settings of your measuring device are not independent of the system being measured — they’re correlated in a way that mimics quantum predictions.

• Pros:

  • Can explain quantum correlations without invoking spooky action or multiple worlds.

• Cons:

  • Philosophically controversial — it seems to undermine scientific method by denying true experimental freedom.

  • Critics say it’s “conspiratorial” — the universe conspires to make quantum mechanics look indeterministic.

Summary Comparison

Feature	Bohmian Mechanics	Superdeterminism
Deterministic?	Yes	Yes
Wavefunction Real?	Yes (guides particles)	Optional (depends on variant)
Randomness Source	Epistemic (hidden variables)	Epistemic (pre-set outcomes)
Measurement Problem	Solved via particle trajectories	Denied via lack of free choice
Philosophical Issues	Nonlocality	Free will, scientific validity

Both challenge the mainstream Copenhagen interpretation, but in radically different ways. Bohmian mechanics keeps quantum weirdness but grounds it in realism. Superdeterminism questions the very freedom of scientific inquiry.