Equation 1 · Part 11 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time
Numerator: ln 2
What this part means
The complete quantity above the fraction bar.
Its job in the formula
ln 2 occurs above the fraction bar. The numerator is divided by the entire denominator below it.
Full expression→Numerator: ln 2→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
A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.
Open the illustrated fractions: division written vertically guide →
Sources cited in the article section
These citations provide research context; check each source for the exact claim it supports.