Part VIII: The Double-Slit Experiment

The Observation

When particles pass through two parallel slits and strike a detection screen, an interference pattern emerges—alternating bands of high and low intensity. This pattern appears even when particles are sent one at a time, suggesting each particle somehow "interferes with itself." Observation of which slit a particle passes through destroys the interference pattern.

The Standard Interpretation

Quantum mechanics interprets this as wave-particle duality. Each particle has an associated wavefunction that passes through both slits simultaneously, interfering with itself. The squared amplitude of the wavefunction gives the probability of detection at each point. Observation collapses the wavefunction, destroying interference. This interpretation, while mathematically successful, leaves unresolved paradoxes regarding what constitutes an "observer" and why observation affects outcomes.

The PSK Interpretation

PSK offers a deterministic, geometric interpretation that eliminates wave-particle duality, observer-dependent collapse, and particles traversing space.

No Transport Particles

PSK rejects photons, electrons-as-projectiles, and all transport particles as ontological entities. Nothing travels through space from source to detector. What we interpret as "particle behavior" is the manifestation of temporal state mapping—causal connections established through past geometric contiguity in sparser density states.

The "particle" detected at the screen is not something that traveled from the source. It is the detector sharing state with the source through the geometric structure established by their past contiguity, modulated by intervening matter (the slit screen).

State-Mapping Channels

Consider the experimental apparatus: a source, a barrier with two slits, and a detection screen. All three are matter traversing into denser spatial states together at rate c. In past density states (when space was sparser), these components were more geometrically proximate—closer to contiguity.

The slit screen does not "block particles." It modulates the geometric channels through which state-mapping between source and detector can occur. Consider a point P on the detection screen. The slit barrier interposes a geometric constraint: only paths through the two apertures permit unobstructed state-mapping.

Point P thus receives state-mapping through two distinct geometric channels—one through each slit. Each channel represents a different geometric path through the density-state history connecting source to detector.

The Origin of Interference

The two channels have different geometric path lengths through density states. This path-length difference creates a phase relationship—not of waves, but of geometric concordance in the state-mapping structure.

Where the two channels arrive at P with concordant geometry (path difference corresponding to constructive alignment), the state-mapping is reinforced—bright fringe. Where the channels arrive with discordant geometry (path difference corresponding to destructive misalignment), the state-mapping partially cancels—dark fringe.

The mathematics is isomorphic to standard wave interference, but the physical interpretation differs entirely: no waves propagate; geometric channels through density-state history combine.

Why Single Particles Show Interference

In standard quantum mechanics, single-particle interference is deeply mysterious—how can one particle go through both slits?

In PSK, the mystery dissolves. There is no particle traveling through slits. The source and detector establish state-mapping through both geometric channels simultaneously because both channels exist in the density-state geometry connecting them. The "particle" is not a thing that went through one slit or the other; it is the manifestation of state-sharing through the combined channel structure.

Why Observation Destroys Interference

"Observing which slit the particle passes through" means placing a detector at one or both slits—introducing additional matter that participates in state-sharing.

When detector matter is placed at a slit, it shares state with whatever state-mapping passes through that channel. This state-sharing interaction modifies the geometric structure. The detector at the slit becomes entangled (shares state) with that channel’s mapping.

The result: the two channels no longer combine freely at the detection screen. The channel with the slit detector has already shared state; its geometric relationship to the other channel is altered. The concordance/discordance pattern is disrupted.

This is not mysterious "observer effect" or consciousness-dependent collapse. It is state-sharing: the slit detector, as matter, participates in the state-mapping geometry, changing the channel structure. Any matter placed to "observe" the path necessarily shares state and modifies the geometry.

Extension to Related Phenomena

Diffraction gratings create multiple geometric channels (one per slit), with the intensity pattern reflecting multi-channel concordance/discordance. Polarization filters impose geometric orientation constraints on state-mapping—permitting only particular orientations. Fresnel lenses create position-dependent path-length modifications that bring multiple channels into concordance at a focal point. All these phenomena admit geometric interpretation without invoking propagating waves.