Equation 6 · Part 3 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time

Symbol e^lambda_238 t

\frac{N_{206}}{N_{238}} = e^{\lambda_{238} t} - 1, \qquad \frac{N_{207}}{N_{235}} = e^{\lambda_{235} t} - 1,

e^{\lambda_{238} t}

What this part means

$e^l$ ambd $a_2$ 38 t is one of the signed contributions combined to compute the quantity on the left.

Its job in the formula

$e^l$ ambd $a_2$ 38 t is one of the signed contributions combined to compute the quantity on the left.

Full expressionSymbol e^lambda_238 tArticle meaning

The passage around this formula

Uranium’s usefulness as a clock is doubled by an accident of nuclear structure: natural uranium consists of two isotopes, uranium-238 and uranium-235, which decay through separate chains to two different stable lead isotopes, lead-206 and lead-207 respectively, at two different, independently measured rates. Uranium-238’s half-life is about four point four seven billion years and uranium-235’s is about seven hundred four million years, values fixed by direct laboratory counting experiments [ 6 ] and formally adopted as the field’s working convention shortly after [ 7 ] . Because both chains run inside the same mineral grain simultaneously, from the same crystallization event, a single zircon…

Read this part in the article →

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 →

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.