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Equation 132 · Part 1 · The Clock That Comes Back Wrong by Exactly Its Mass

Symbol Δ E

ΔE/c2\Delta E/c^2
ΔE\Delta E

What this part means

Δ E is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

Δ E is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

This is where the operational construction earns or loses its claim to be a mass gauge rather than a definition with no experimental content. Distinguish two separate clauses of Einstein’s equivalence principle. The weak equivalence principle protects the laser/center-of-mass term, forcing it to be mass-independent; that is not this paper’s target, and no version of LP\mathcal L_{\rm P} challenges it. Local position invariance — the universality of clock rates across spacetime position — is the clause the internal-energy term actually probes, and it is a logically separate statement, untouched by the weak equivalence principle’s guarantee. The kill criterion for this whole construction is now…

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A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the surrounding passage

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