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Equation 132 · Part 3 · The Clock That Comes Back Wrong by Exactly Its Mass

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ΔE/c2\Delta E/c^2
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What this part means

Capital delta attached to a quantity marks a difference between two values of that quantity; the article’s sign convention determines the order.

Its job in the formula

Capital delta attached to a quantity marks a difference between two values of that quantity; the article’s sign convention determines the order.

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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Learn the underlying idea

Addition combines quantities; subtraction measures the signed difference between them. Parentheses show what is combined before the rest of the expression is evaluated.

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Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.