So, if we say something is 1 billion years old, is that (365 spins on earth’s axis x 1 billion)? Is it (1 trip around the sun x 1 billion), or a different measurement? The answers to those change depending on how it’s calculated.
In other words, if I say I lived one year, that means 24 hr/day for 365 days/year in todays terms. Over time the earth’s orbit of the sun becomes faster and slower changing the meaning of a year. Also, as the earth spins faster and slower on its axis, a day in terms of hours is different relative to today. It breaks my brain.
What about the needs for adjustments for leap years? How does this influence radiometric dating? If a molecule degrades by 1 measurement every 300,000 years, the first 150,000 years are going to be different than the last half. If you want to pinpoint the halfway mark, where is it?
In: Planetary Science
I’m surprised that nobody has pointed out that all methods of measuring geologic time aren’t measuring units of time in the first place, they are measuring things like the ratio of one isotope to another, which can then be converted into a measurement of time. Think of it this way, if you drop a marble exactly every second and count 60 marbles over an interval, then you have measured how many marbles dropped then used the known rate to convert to a measurement of time. For measuring geologic time there isn’t some kind of big caliper with a clock attached.
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