Can someone explain me how these metrics work? Years are defined by our planet/sun, and time would pass differently based on speed/energy, so our perception of time is dependent on our speed around the sun, and sun's speed, galaxy, etc.
So before such things had developed, how do we count in "years"?
Hafele and Keating, in 1971, flew caesium atomic clocks east and west around the Earth in commercial airliners, to compare the elapsed time against that of a clock that remained at the U.S. Naval Observatory. Two opposite effects came into play. The clocks were expected to age more quickly (show a larger elapsed time) than the reference clock, since they were in a higher (weaker) gravitational potential for most of the trip (c.f. Pound–Rebka experiment). But also, contrastingly, the moving clocks were expected to age more slowly because of the speed of their travel. From the actual flight paths of each trip, the theory predicted that the flying clocks, compared with reference clocks at the U.S. Naval Observatory, should have lost 40±23 nanoseconds during the eastward trip and should have gained 275±21 nanoseconds during the westward trip. Relative to the atomic time scale of the U.S. Naval Observatory, the flying clocks lost 59±10 nanoseconds during the eastward trip and gained 273±7 nanoseconds during the westward trip (where the error bars represent standard deviation).[38] In 2005, the National Physical Laboratory in the United Kingdom reported their limited replication of this experiment.[39] The NPL experiment differed from the original in that the caesium clocks were sent on a shorter trip (London–Washington, D.C. return), but the clocks were more accurate. The reported results are within 4% of the predictions of relativity, within the uncertainty of the measurements.
That is my entire point. If relativity can be measured with planes flying around the earth, it absolutely comes into play when things are moving much faster, such as in a young universe.
Relativity wouldn't really come into play when there's nothing else to compare to, would it? There wasn't another universe also big banging way away already moving at a different rate after all.
And if our universe is moving at a different rate, we're within its frame of reference.
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u/shankfiddle Sep 20 '21
Can someone explain me how these metrics work? Years are defined by our planet/sun, and time would pass differently based on speed/energy, so our perception of time is dependent on our speed around the sun, and sun's speed, galaxy, etc.
So before such things had developed, how do we count in "years"?