Radiometric dating wrong
Over time, the amounts of Pb-206 and Pb-207 will change in some samples, as these isotopes are decay end-products of uranium decay (U-238 decays to Pb-206, and U-235 decays to Pb-207).
This causes the data points to separate from each other.
A plot is constructed of Pb-206/Pb-204 versus Pb-207/Pb-204.
If the solar system formed from a common pool of matter, which was uniformly distributed in terms of Pb isotope ratios, then the initial plots for all objects from that pool of matter would fall on a single point.
It looks like this: Most of the other measurements for the age of the Earth rest upon calculating an age for the solar system by dating objects which are expected to have formed with the planets but are not geologically active (and therefore cannot erase evidence of their formation), such as meteorites.
Below is a table of radiometric ages derived from groups of meteorites: As shown in the table, there is excellent agreement on about 4.5 billion years, between several meteorites and by several different dating methods.
The current level of helium in the atmosphere would accumulate in less than two hundred thousand years, therefore the Earth is young.
) and they are historically the ones posted to talk.origins more than any others.
The young-Earth argument goes something like this: helium-4 is created by radioactive decay (alpha particles are helium nuclei) and is constantly added to the atmosphere.
(I believe this argument was originally put forth by Mormon young-Earther Melvin Cook, in a letter to the editor which was published in .) But helium can and does escape from the atmosphere, at rates calculated to be nearly identical to rates of production.
In order to obtain a young age from their calculations, young-Earthers handwave away mechanisms by which helium can escape.
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While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it).