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T(b)G(v)T(−b)G(−v)T(\mathbf b)G(\mathbf v)T(-\mathbf b)G(-\mathbf v)

Why this formula appears here

Nothing about this phase disturbs conservation of energy or momentum, and it is worth saying explicitly why. Φ\Phi[LG\mathcal L_{\rm G}] does not come from a new term added to any Hamiltonian; it comes from how already-unitary translation and boost operators compose. Each operator in the product T(b\mathbf b)G(v\mathbf v)T(-b\mathbf b)G(-v\mathbf v) conserves probability on its own, and the product of unitaries is unitary regardless of whether the factors commute, so the loop as a whole still conserves probability and leaves every expectation value of energy and momentum exactly where an ordinary, non-extended calculation would put it. What changes is not a conserved quantity but the bookkeeping of…

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TT

Symbol T

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bb

Symbol b

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GG

Symbol G

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vv

Symbol v

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Published contexts (1)

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T(b)G(v)T(−b)G(−v)T(\mathbf b)G(\mathbf v)T(-\mathbf b)G(-\mathbf v)

Equation 50 · Evolutionary Physics

The Clock That Comes Back Wrong by Exactly Its Mass

This mathematical expression combines the displayed quantities; its precise role follows from the surrounding article text.

Nothing about this phase disturbs conservation of energy or momentum, and it is worth saying explicitly why. Φ\Phi[LG\mathcal L_{\rm G}] does not come from a new term added to any Hamiltonian; it comes from how already-unitary translation and boost operators compose. Each operator in the product T(b\mathbf b)G(v\mathbf v)T(-b\mathbf b)G(-v\mathbf v) conserves probability on its own, and the product of unitaries is unitary regardless of whether the factors commute, so the loop as a whole still conserves probability and leaves every expectation value of energy and momentum exactly where an ordinary, non-extended calculation would put it. What changes is not a conserved quantity but the bookkeeping of…

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