USP Field Theory — How Thermometers Work: Δf Transfer and Equilibrium Detection

This document explains the operation of thermometers through the lens of USP Field Theory. Temperature is reframed not as an abstract scalar but as the manifestation of Δf (frequency mismatch) within oscillating systems. From the first liquid-in-glass devices to modern infrared laser thermometers, all measurement methods are unified as processes of resonance transfer and equilibrium detection. This reinterpretation demonstrates that every thermometer is, fundamentally, a Δf detector translating microscopic oscillatory tension into macroscopic readings. 🔹 Harmonization Note (DOI Integration) This publication is harmonized with the experimental foundation established in USP Field Theory – Temperature & Resonance: Testable Experiments (2025), DOI: 10.5281/zenodo.16788099. That work defines the laboratory verification path for Δf relaxation, η-controlled transparency, and resonant thermal emission, providing the testable framework for all Δf-based temperature, energy, and transparency laws across the USP Field Theory series (msf: 45706 – 45714).