He is presently employed in the Space & Atmospheric Sciences Group at the Los Alamos National Laboratory.
Radiometric dating--the process of determining the age of rocks from the decay of their radioactive elements--has been in widespread use for over half a century.
If there are a lot of atoms of the original element, called the parent element, the atoms decay to another element, called the daughter element, at a predictable rate.
The passage of time can be charted by the reduction in the number of parent atoms, and the increase in the number of daughter atoms.
However, some elements are not completely stable in their natural state.
Some of the atoms eventually change from one element to another by a process called radioactive decay.
This paper describes in relatively simple terms how a number of the dating techniques work, how accurately the half-lives of the radioactive elements and the rock dates themselves are known, and how dates are checked with one another.Radiometric dating can be compared to an hourglass.When the glass is turned over, sand runs from the top to the bottom.Other things to look for include chasses placed in cabinets from a different year, “doctored” tube charts, non-original control plates (usually reproductions) on silverface amps, original transformer bell ends (they have correct date codes, of course) on non-original transformers, and non-original knobs (either repro or silverface knobs on blackface amps).unusual things can be found such as the empty “Pulse Adjust” hole on the rear of early ’60 brown amps, the “middle” volume control, use of tweed style grill cloth, strange non-documented transitional circuits, and changes in tolex color including the super-rare cream colored “brown” tolex that is found on some late ’60 amps. Given that people may refer to this information seeking specific production quantities of amps they are curious about, it should be pointed out that the serial numbers apply to chassis types, and not specifically to amplifier models.Looking at serial numbers next to the ’60 5G5 brown Pro Amp for example, we see numbers ranging from 00001 to 02000, suggesting that there are 2000 of these amplifiers made in ’60.