On Tue, 1 Nov 2016 15:25:28 -0400, Tony Harminc wrote: > >And in the familiar case where the numerator is in a length unit (say, >m), and the denominator in a time unit (say, s), we have names for >each level: distance, speed, acceleration, jerk. > "jerk"? Is anyone much concerned with "jerk" nowadays except for the Dean Drive jerks?
>In this case we have time/time/time, which just fails to jump out at >me. Maybe my imagination, visual or otherwise, is lacking. > Earlier, I posted the reciprocal of that number with the dimensions collapsed to about 6x10^9 years, which is a plausible Fermi estimate for the time it will take the moon to drag the earth to a halt. >> The epoch being used in computer systems is 1972, with 26 leap seconds >> counted since then. > >Not any computer systems I work with. They use either 1900 or 1970 as >their epoch. What uses 1972? > 1972 was the inception of UTC. At that time, GMT was 10 seconds behind TAI. MVS chose to set its TOD clock to GMT at that instant and run it at the TAI rate thereafter, which is why TAI is (now) 36 seconds ahead of UTC but TOD is only 26 seconds ahead of UTC. All the curves intersect in 1972. The units of Hubble's Constant are km/sec/megaparsec. Inverse time in some units. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
