The QM measurement problem in DEF
The QM measurement problem is basically this tension:
- Unitary evolution (Schrödinger equation): the wavefunction evolves smoothly and deterministically into superpositions.
- Measurement (what we actually see): you always get one definite outcome (a click here, not there).
- But standard QM doesn’t clearly say what physically counts as a “measurement” or how a single outcome is selected without adding extra rules (collapse), extra worlds (Many-Worlds), or extra hidden stuff (Bohm).
So the problem is: What is the real, physical mechanism that turns “both” into “one”? And why does that mechanism only show up when “measurement” happens?
A Differential Expansion Framework (DEF) -style answer (mechanical, not mystical)
In DEF, “quantum states” aren’t floating abstractions; they are real patterns in the causal expansion field that must maintain closure under a finite causal throughput. A “measurement” is not a magical act of observation; it is a forced coupling between a delicate, partly coherent field pattern (the system) and a large, lossy, many-mode field object (the apparatus + environment).
1) Superposition = multiple closure-compatible modes
In DEF terms, a “superposition” is a situation where the system’s circulating/standing pattern can remain self-consistent in more than one mode at once because it is still underconstrained.
- Think: several possible stable phase-closure routes are still allowed.
- The wavefunction is a bookkeeping of these allowed causal-closure modes (with complex amplitudes representing phase relations).
2) A measuring device is a “closure amplifier”
A detector isn’t passive. It’s a huge structure with:
- enormous internal degrees of freedom (phonons, electrons, lattice modes, thermal noise),
- irreversible dissipation pathways,
- and—crucially in DEF—very high “capture/attenuation opportunity” for the causal field.
So when the system interacts with the apparatus, it’s not “being looked at”; it’s being forced to share closure with something that has many more constraints than it can satisfy simultaneously.
3) The “collapse” is constraint-selection via irreversible capture
DEF’s mechanical version of collapse is:
One branch becomes the only branch that can maintain causal closure once the system is entangled with a macroscopic, lossy sink.
Why only one?
Because the apparatus interaction is nonlinear in practice (even if underlying micro-laws are causal): tiny differences in phase alignment determine whether the device triggers a self-reinforcing macroscopic cascade (avalanche, latch, bubble track, photochemical change, etc.).
Once one cascade begins, it attenuates and locks the local causal throughput into that outcome’s channel, and competing branches lose the causal “budget” needed to remain coherent as a whole device+system state. They don’t “vanish by magic”; they become physically unmaintainable as coherent closures and disperse into inaccessible microstructure (what standard QM calls decoherence).
So in DEF language:
- “Collapse” = closure becoming single-valued under strong coupling to a sink.
- “Randomness” = untracked microscopic phase of the apparatus/environment deciding which closure channel reaches runaway first.
4) Born rule (why probabilities are |ψ|²)
DEF can motivate the Born rule as a flux/throughput partition rule:
- The amplitude ψ encodes how much coherently directed causal throughput reaches a given outcome channel under the interaction constraints.
- Measurement is a capture competition among channels.
- The rate at which a channel “wins” depends on power-like availability of coherent throughput, not the signed amplitude itself (phases interfere, but captured energy/activation is positive). That naturally pushes you toward an intensity law ∝ |ψ|².
So |ψ|² is interpreted as:
the fraction of causal throughput that can be stably captured into that macroscopic outcome channel, given the device coupling.
5) Why “classical reality” emerges
Macroscopic objects are constantly exchanging causal throughput with their environment. That means:
- their state is always being closure-selected and redundantly recorded (in DEF: the environment continually “copies” stable closure patterns),
- so they sit in robust “pointer” modes (position-ish, orientation-ish, etc.),
- and superpositions of macroscopically different states are closure-fragile: they require implausibly precise global phase coordination across huge numbers of degrees of freedom.
That’s basically decoherence—but DEF gives it a mechanical why: macroscale closure cannot sustain multi-branch coherence under continual attenuation/capture.
One clean picture to hold in your head
- Before measurement: a small rotor/standing pattern can “afford” several compatible closure routes → superposition.
- During measurement: it couples to a massive sink with many degrees of freedom → closure constraints explode.
- After measurement: only one global closure route survives as a self-reinforcing macroscopic latch → definite outcome.
So DEF treats the measurement problem as:
“When does a field pattern stop being underconstrained and become overconstrained?”
Measurement is precisely the overconstraint event.
How this differs from common interpretations (quickly)
- Copenhagen: says collapse happens but doesn’t specify a mechanism.
DEF: collapse = physical closure-selection under attenuation + irreversibility. - Many-Worlds: keeps unitary evolution, branches all persist.
DEF: branches can exist as mathematical decompositions, but only one becomes a macroscopically maintainable closure; the rest devolve into non-reconstructible microphase structure (physically real as noise, not as “other worlds you could in principle access”). - Objective collapse models: add new stochastic dynamics.
DEF: you don’t need new fundamental randomness; you get effective randomness from uncontrolled apparatus microphase while enforcing finite causal budget + irreversible capture.