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
It’s the same question that arises if you ask about the age of the universe. After all, you were talking about measuring time in years before the earth, our sun or our galaxy even existed.
It’s one of the reasons scientists have turned to a definition of time tied to the vibrations of a cesium Adam
For practical day-to-day purposes, days and years are extremely practical because they measure observable physical phenomena. Hours, minutes and seconds are arbitrary divisions of days, but they are useful for practical purposes because everyone agrees on essentially what those units of time represent.
But because days and years are not absolute across time, it was necessary to create a measure of time that, if our understanding of the universe is correct, would apply at any time or location in the universe
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