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Equation 56 · Part 1 · No Particle Without a Cosigner

Symbol dot a

a˙\dot a
a˙\dot a

What this part means

the expanding in powers of.

Its job in the formula

dot a has a dot, marking the rate of change of the underlying indexed quantity with respect to the article’s time variable.

Where the article explains it

Barbado and Visser worked out the response of a detector whose acceleration a(τ\tau) varies with proper time, expanding in powers of a˙\dot a , a¨\ddot a , and higher proper-time derivatives of the acceleration [ 8 ] .

The passage around this formula

…where the eternal-acceleration answer above starts to strain, is slow time dependence. Barbado and Visser worked out the response of a detector whose acceleration a(τ\tau) varies with proper time, expanding in powers of a˙\dot a , a¨\ddot a , and higher proper-time derivatives of the acceleration [ 8 ] . At leading order, wherever the acceleration changes slowly compared to the local orthogonalization timescale it sets for itself, the detector reports the instantaneous Unruh temperature TU(a(τ)T_U(a(\tau)) at each moment, as…

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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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