SkipCaptcha, Automoderated users, edit
3,266
edits
Changes
Jump to navigation
Jump to search
Line 101:
Line 101: − − == Explanation by Analogy == − − No method exists for ''measuring'' [[time]], except by measuring it as it is passing. Therefore, the age of an artifact must be ''calculated''. − − The basic principle in any dating method is to find a process that is occurring at a measurable rate and which is causing a change, measure the rate of that process, work out what state the artifact was in at the beginning of the process, observe what state it is in now, and to calculate how long the process at the measured rate would need to occur to effect that change. − − For example, to work out how long a [[candle]] has been burning, the following steps would be needed: − # Measure how long it takes the candle to burn down a given amount. − # Find out how long the candle was when it started burning. − # Measure how long the candle is now. − # Calculate the difference between the two lengths. − # Calculate how long it would need to burn in order to burn that length. − − For most radiometric dating methods, one radioactive element changes by a process of nuclear decay into another element (often through a number of intermediate steps). For example, [[uranium]] will eventually decay into [[lead]]. So to measure how old a specimen containing some uranium and some lead is, the following steps are required: − # Measure the decay rate of uranium. − # Find out how much uranium was in the specimen to start with (this might be done by assuming that all the lead was originally uranium). − # Find out how much uranium is in the specimen now. − # Calculate how much uranium has turned into lead. − # Calculate how long it would take that much uranium to turn into lead, given the measured rate. Calculations involve the well-established function for exponential decay: <math>F</math><sub><math>t</math></sub><math>=e</math><sup><math>-kt</math></sup>. − −
Radiometric dating (view source)
Revision as of 22:49, September 21, 2019
, 22:49, September 21, 2019Remove the candle stuff. That analogy is not at all helpful, and its removal was recommended on the talk page 12 years ago. People can understand the principle quite well from the current radioactivity page.
#[[Uranium-thorium]]
#[[Uranium-thorium]]
#[[Rubidium-strontium dating]]
#[[Rubidium-strontium dating]]
== Bibliography ==
== Bibliography ==