Equation 11 · Part 6 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time
=
=
What this part means
The expressions on both sides represent the same quantity under the stated assumptions.
Its job in the formula
The equals sign connects the complete expression on the left with the complete expression on the right. Both sides must have compatible units.
Full expression→=→Article meaning
The passage around this formula
The uranium-lead and argon-argon methods both need to know, or be able to ignore, how much daughter isotope was already present when the mineral formed. The isochron method, used most often with the rubidium-strontium and samarium-neodymium systems, solves this by measuring several minerals from the same rock, each of which crystallized from the same well-mixed magma at the same time and so began with the same strontium or neodymium isotopic composition, but which incorporated different amounts of the radioactive parent isotope depending on their individual chemistry. Plotting each mineral’s present-day ratio of radiogenic daughter to stable reference isotope against its ratio of parent to…
Learn the underlying idea
An equals sign says that the expression on its left and the expression on its right have the same value under the stated definitions and assumptions.
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Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.