3 ms·

> We have clocks which can measure it over just a few feet of height difference Wait, seriously? Do you have a link??

• colechristensen 7y ago
  Measuring the height of a mountain with a portable atomic clock (1000m accuracy) https://www.nature.com/articles/s41567-017-0042-3 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 https://science.sciencemag.org/content/329/5999/1630.long
  • raattgift 7y ago
    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_files/I08-VanBaak-GPS_Flying_Clocks_and_Relativity.pdf http://web.stanford.edu/group/scpnt/pnt/PNT18/presentation_f... (slides) Or if you prefer non-PDF: http://leapsecond.com/great2005/ http://leapsecond.com/great2005/ http://leapsecond.com/great2016a/ http://leapsecond.com/great2016a/
  • mehrdadn 7y ago
    Amazing. They observe fractional frequency changes of around 4.1E-17. Thanks for sharing the links!
    • ta1234567890 7y ago
      Couldn't see that number in the info at the link above, is that from the full article?
      • mehrdadn 7y ago
        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."