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Equation 11 · Part 1 · Radioactive Clocks: How Nuclear Physics Gave Evolution Its Time

Symbol R_t

Rt=R0+N87N86(eλt−1),R_t = R_0 + \frac{N_{87}}{N_{86}}\left(e^{\lambda t} - 1\right),
RtR_t

What this part means

each mineral’s measured present-day strontium-87 to strontium-86 ratio.

Its job in the formula

RtR_t is part of the quantity the equation computes from the expression on the right.

Where the article explains it

where RtR_t is each mineral’s measured present-day strontium-87 to strontium-86 ratio, R0R_0 is the shared initial ratio recovered as the line’s intercept, and N87N_{87}/N86N_{86} is each mineral’s measured rubidium-87 to strontium-86 ratio [ 18 ] .

The passage around this formula

…to stable reference isotope against its ratio of parent to reference isotope produces a straight line whose slope gives the age and whose intercept gives the initial composition directly: Rt=R0+N87N86(eλt−1)R_t = R_0 + \frac{N_{87}}{N_{86}}\left(e^{\lambda t} - 1\right). where RtR_t is each mineral’s measured present-day strontium-87 to strontium-86 ratio, R0R_0 is the shared initial ratio recovered as the line’s intercept, and N87N_{87}/N86N_{86} is each mineral’s measured rubidium-87 to strontium-86 ratio [ 18 ] . The initial composition is no longer an assumption fed into the…

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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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