Equation 14 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time
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Symbol N_87
7 is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
subscript
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where is each mineral’s measured present-day strontium-87 to strontium-86 ratio, is the shared initial ratio recovered as the line’s intercept, and / is each mineral’s measured rubidium-87 to strontium-86 ratio [ 18 ] . The initial composition is no longer an assumption fed into the calculation; it is an output the data themselves supply, and a poor fit to a straight line is itself a warning that the minerals did not, in fact, share a common origin or have remained closed systems since.
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