Theoretically if in early years the earth was moving at an astronomically different pace (whether in orbit or rotation, whatever sounds better) wouldn't that alter the science of carbon dating? As I understand time relativity, If the speed at which the earth was moving changes, the elements and organisms there-in would experience time at a different rate. Would we not expect that carbon would decay faster? I know it's just theory but I'd like to know if this theory could be proven false. And is there any existing research that you are aware of that would support or debunk this theory?

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    $\begingroup$ This is a question about the relativistic effects on the rate of radioactive decay. Carbon dating is just one application of radioactive decay. While it is an interesting question, I'm pretty sure the people over at Physics.SE would know how to better answer this. $\endgroup$ – Gimelist Sep 5 '15 at 0:13
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    $\begingroup$ Relativity doesn't work like that. If everything is on Earth, then everything 'experiences' time equally. To dilate time, you need relative motion. $\endgroup$ – kwinkunks Sep 5 '15 at 8:40
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    $\begingroup$ There is a distinct difference between theory, hypothesis, and speculation. $\endgroup$ – BillDOe Sep 5 '15 at 18:47

Earth travels along its orbit at about 30km/s. If you plug that number into a time dilation calculator, you'll find that one second on Earth passes every 1.0000000050069 seconds in a Sun-centric reference frame.

Carbon-14 dating is good only to about 40,000 years into the past; Earth's time dilation would reduce that 40,000 years by a little under two hours, or far below the precision of the technique.

Edit: I'd like to address three more issues. First, the rotation of the Earth's surface only results in about 0.5km/s at the equator, and so is insignificant compared to the orbital velocity. Second, nothing has changed the Earth's orbit for many millions of years, probably for billions of years, so that would also have no effect on the dating.

Third, and more important, we're all traveling along on the Earth at (approximately) the same speed. So you, I, and a group of C-14 atoms in a fossil will all experience the same time dilation.

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  • $\begingroup$ You have actually peaked my interest more. If there were rotational time dilation, and orbital time dilation, wouldn't there also be galactic or universal time dilation according to the speed with which our elements are moving through the larger space. And wouldn't these speeds be much greater? Also, isn't it known that those speeds are changing fairly rapidly as the universe expands? $\endgroup$ – justwondering Apr 9 '16 at 22:55
  • $\begingroup$ Third: We would experience the same time dilation, true, but not if we weren't in the same time frame. The time dilation that carbon atoms would experience today may be greater or smaller than it was 3000 years ago right? Yet it's all calculated based on a constant time and rate of decay, right? $\endgroup$ – justwondering Apr 9 '16 at 22:59
  • $\begingroup$ @justwondering But how do you measure "3000 years ago", except by methods which are affected by the same time dilation? Are you thinking that there's an official timepiece floating in space somewhere that you can refer to? There isn't: we're all moving along on the same Earth at essentially the same velocity. So, from our viewpoint, there's no net effect. $\endgroup$ – Daniel Griscom Apr 10 '16 at 3:42
  • $\begingroup$ Granted there is no official time piece, but why then are we assuming time is constant? Doesn't evidence actually show that the speed of expansions of the universe has been varying with things like inflation at the beginning and now dark matter acceleration? So isn't it fair to assume that based on galactic and universal speeds not always being constant then time has also not been constant? And again I understand that we are all moving along the same earth but old carbon atoms may have been moving along an earth that was moving inside a universe at a larger velocity $\endgroup$ – justwondering Apr 10 '16 at 17:32

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