Volume 27 · Part Four · Chapter 16 of 19
Where the Proxies Predict Well
The record, stated without discount.
The successes, itemised
Linearised gravity: light deflection, Shapiro delay, and orbital decay of binary pulsars matched to high precision; frame dragging confirmed by satellite gyroscopy and by lunar and satellite laser ranging. The weak-field proxy is one of the best-tested approximations in physics.
Analogue systems: Hawking-mode correlations in condensate horizons; stimulated horizon effects in water tanks and nonlinear optics. The kinematic claim of Chapter 5 has held under test.
Wave-packet and continuum pictures: Rydberg packet revivals and fractional revivals predicted and observed; spectral statistics of chaotic billiards matching random-matrix predictions; scarring observed in microwave cavities and in quantum dots.
Topological matter: quantum Hall conductance quantised to parts in a billion, precise enough to serve as a resistance standard; edge transport in topological insulators; measured optical orbital angular momentum.
What the successes have in common
Every entry on that list is a case where the proxy's validity band was stated in advance and the experiment was performed inside it. That is the whole pattern. Proxies do not fail because they are proxies; they fail when they are used outside a band nobody bothered to write down. The successes are the argument for keeping the borrowings, not against them.
Equations borrowed
- The experimental record cited in Chapters 2–14
Validity band
Each result holds in the regime of its own experiment; none of them licenses extrapolation beyond it.
Falsifier
Failure of any listed result to replicate at stated precision.
Where this chapter is weakest
The chapter summarises rather than assesses. Several entries would benefit from the specific numbers and citations, and the analogue-Hawking results in particular remain contested in interpretation by a minority of the field.
The volume-wide audit of these weak points is collected in Where This Volume Is Weak.