[colechristensen]

Time isn't universal, it doesn't tick for everybody at the same rate, in fact every particle has its own unique clock.

One thing that changes how your clock flows is being in a gravity well. We have clocks which can measure it over just a few feet of height difference. Gravity isn't so much a "force" but the bending of space and time. Clocks moving differently is the result.

[mehrdadn]

> We have clocks which can measure it over just a few feet of height difference

Wait, seriously? Do you have a link??

[colechristensen]

Measuring the height of a mountain with a portable atomic clock (1000m accuracy) https://www.nature.com/articles/s41567-017-0042-3

NIST measuring speed differences < 10 m/s and height < 1 m with a pair of atomic clocks https://science.sciencemag.org/content/329/5999/1630.long

[raattgift]

Tests of gravitational time dilation are also within the reach range of enthusiastic amateurs using second-hand atomic clocks:

Part 4 (starting pdf page 44) of http://web.stanford.edu/group/scpnt/pnt/PNT18/presentation_f... (slides)

Or if you prefer non-PDF:

http://leapsecond.com/great2005/

http://leapsecond.com/great2016a/

[mehrdadn]

Amazing. They observe fractional frequency changes of around 4.1E-17. Thanks for sharing the links!

[ta1234567890]

Couldn't see that number in the info at the link above, is that from the full article?

[mehrdadn]

Yeah: "The two measurements consist of approximately 100,000 s of low-height data and 40,000 s of high-height data, and the clocks exhibit (Fig. 3) a fractional frequency change of (4.1 ± 1.6) × 10^−17."