Quantum tunnelling is responsible for nuclear fusion in stars, alpha decay in radioactive nuclei, the operation of tunnel diodes, and scanning tunnelling microscopes. It is one of quantum mechanics' most practically important effects. It is also, in the standard interpretation, deeply counterintuitive: a particle passes through an energy barrier it classically cannot cross.
BFUT Paper 19A gives it a physical substrate interpretation that removes the counterintuitive element entirely.
The Physical Picture
In BFUT, a potential barrier is a region of elevated substrate deformation energy - a region where the substrate's configuration resists the passage of a condensation. A condensation approaching the barrier has a substrate deformation field with a finite spatial extent set by its coherence length - the characteristic scale over which the condensation's deformation pattern remains correlated.
If the barrier width is comparable to or smaller than the coherence length, the deformation pattern has non-zero amplitude on the far side of the barrier. The condensation does not pass through the barrier material. The substrate deformation pattern reorganises continuously across the barrier when the geometry permits it - the same way that a water wave propagates through a narrow gap without the water itself passing through in discrete pieces.
The Tunnelling Probability
The tunnelling probability is determined by the ratio of barrier width to the coherence length of the substrate deformation: wider barriers relative to the coherence length give exponentially smaller tunnelling probability. This is precisely the quantum mechanical result - exponential suppression with barrier width and height - but derived from the physical geometry of substrate deformation instead of postulated from the Schrödinger equation.
Energy Conservation
The condensation does not violate energy conservation and does not travel faster than c. The substrate simply reorganises continuously. If the geometry of the barrier allows continuity of the deformation pattern across it, the condensation appears on the far side. The energy remains constant throughout - what changes is the spatial configuration of the deformation pattern, not its total energy.
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