Who invented radioactive dating
Usually, different amounts of lead will have been lost, for example more from the surface of the crystal than from the interior, so there will be a range of isotope ratios.If the differences are due to one episode of loss of lead, then these points will lie on a straight line, as is often observed.For example, the geological formations and dates from surrounding features may suggest that the "true" date can only lie within a certain range.As another example, a date that is obviously wrong would confirm a strong belief in the fundamental unreliability of radioactive dating.As uranium decays to two different isotopes of lead at different rates of decay, two clocks are inherently built into the system.If the two agree with each other, the confidence in the date will be high.
It is impossible to measure the age of something, except to time it as it actually occurs, so radioactive dating methods calculate the age, based on (i) measurements of quantities of specified materials, (ii) measurements of decay rates, and (iii) assumptions about the history of the sample.
For example, isochron methods do not assume any particular concentration of the daughter isotope in the original sample, but calculate that concentration based on other measurements.
The reliability of that calculation will in turn depend on other conditions.
Carbon-14 for example is considered accurate by its supporters on ages from 2 to 50 thousand years.
Modern methods can detect essentially any Carbon-14, and therefore produce dates up to about 100,000 years.
We could measure (a) how much water the tank holds, (b) how much is still in the tank, and (c) the rate at which it is leaking out.