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Equation 103 · Part 1 · The Clock That Comes Back Wrong by Exactly Its Mass

Symbol Δτ

Δτ\Delta\tau
Δτ\Delta\tau

What this part means

Δτ 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

Δτ 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

…the standard bookkeeping in which a system’s total rest energy Mc2c^2 includes whatever internal energy HintH_{\rm int} it holds: M=M0M_0+HintH_{\rm int}/c2c^2 . If the same object is sent along two paths that differ in proper time by Δ\Deltaτ\tau , and its internal state differs between the two paths — ground on one, excited on the other — then the two branches’ free-particle phases differ by

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Learn the underlying idea

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 article section

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