Equation 11 · Part 3 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time
Symbol N_87
What this part means
7 occurs above the fraction bar. The numerator is divided by the entire denominator below it.
Its job in the formula
7 occurs above the fraction bar. The numerator is divided by the entire denominator below it.
Full expression→Symbol N_87→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
A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.
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Sources cited in the surrounding passage
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