Symbol a_1

Its job in the formula

$a_1$ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Where the article explains it

Two worldlines held at accelerations $a_1$ and $a_2$ therefore differ only by which Planck-shaped curve their normalized spectrum traces, and identical accelerations trivially return $D_{\rm det}$=0 — the reparametrization check every metric has to pass, satisfied here for the most literal reason available: identical trajectories are, in fact, identical.

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →