Equation 1 · Part 4 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time
Symbol e^-λ t
What this part means
λ t is one of the signed contributions combined to compute the quantity on the left.
Its job in the formula
λ t is one of the signed contributions combined to compute the quantity on the left.
Full expression→Symbol e^-λ t→Article meaning
The passage around this formula
The property that makes radioactive decay useful as a clock is not that it happens on a convenient timescale — some isotopes decay in fractions of a second, others over timescales longer than the universe’s age — but that it happens with no memory. An atom of uranium-238 that has existed, undecayed, for four billion years is exactly as likely to decay in the next second as one formed a microsecond ago. There is no wear, no fatigue, no accumulated probability of failure the way there is in a mechanical clock’s escapement or a living organism’s senescence. This absence of memory is what makes decay first-order: the number of decays in a short interval is proportional only to the number of…
Learn the underlying idea
An exponent tells how a base is used in multiplication. In x³, x is the base and 3 is the exponent: x³ = x × x × x.
Open the illustrated exponents: repeated multiplication and powers guide →
See this notation across published equations →
Sources cited in the article section
These citations provide research context; check each source for the exact claim it supports.