← All parts of this equation

Equation 55 · Part 2 · No Particle Without a Cosigner

Symbol τ

a(τ)a(\tau)
τ\tau

What this part means

τ 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

τ 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

A second limit worth naming, because it is 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 though briefly and locally eternal. This adiabatic recovery is the second known limit this construction inherits rather than derives: it…

Read this part in the article →

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.

Open the illustrated variables: a letter stands for a value guide →

See this notation across published equations →

Sources cited in the surrounding passage

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