Equation 104 · Part 2 · The Clock That Comes Back Wrong by Exactly Its Mass

Symbol Δ E

\Delta\phi_{\rm clock}=-\frac{\Delta E}{\hbar}\,\Delta\tau.

\Delta E

What this part means

the energy.

Its job in the formula

Δ E occurs above the fraction bar. The numerator is divided by the entire denominator below it.

Full expressionSymbol Δ EArticle meaning

Where the article explains it

A composite system with an internal excitation of energy $\Delta$ E above its ground configuration carries additional rest mass $\Delta$ E/ $c^2$ , by ordinary mass–energy equivalence — no redefinition of either the relativistic or the everyday meaning of mass, simply the standard bookkeeping in which a system’s total rest energy M $c^2$ includes whatever internal energy $H_{\rm int}$ it holds: M= $M_0$ + $H_{\rm int}$ / $c^2$ .

The passage around this formula

… $L_{\rm P}$ is where mass stops being a fixed label and becomes something an object can carry a little more or less of depending on what it is doing internally. A composite system with an internal excitation of energy $\Delta$ E above its ground configuration carries additional rest mass $\Delta$ E/ $c^2$ , by ordinary mass–energy equivalence — no redefinition of either the relativistic or the everyday meaning of mass, simply the standard bookkeeping in which a system’s total rest energy M $c^2$ includes whatever internal…

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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 surrounding passage

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