Four Big Misrepresentations about Time Conversion
Extracted from the Comments section of "Fixing the Longitude Problem ..."
1. A Big Ben strike is a “moment in time identical for everyone” in Australia, England and elsewhere. Furthermore, he said, “this moment occurs simultaneously across the entire Earth … regardless of the observer and their [sic] local clock readings.”
This particular “moment” is astronomically applicable ONLY to Big Ben and to observers at 0°07'28.31"W, its longitude. It’s arbitrarily synchronized to the Greenwich meridian, however, and since it’s west of that, it doesn’t strike accurately at noon Greenwich for its precise location – it does so 29.89s LATER than 12:00 UT1, since time is EARLIER to the west, i.e., 12:00:29.89 CT.
2. It was suggested that I’m proposing “a return to Local Mean Time (LMT),” where, in such a case, the “the minute hand does not align with 12.”
The first part is an obvious misrepresentation, since I’ve never proposed that; in fact, I’ve discouraged anyone from thinking about it! I propose, if he’d read my articles, a correction to the standard formula (CT = UTC – ΔT_zone) for converting civil time to UTC (Coordinated Universal Time - an atomic time scale). That correction is the LMT variation: CT = UT1 - ΔT_zone - [(λ_obs - λ_std) × 4 / 60] or more simply: standard time = universal time - time-zone offset - LMT variation … where the LMT variation is the distance in time east from the standard meridian, UT1 (synonymous with GMT) = a rotational time scale, and CT = civil or standard time, ΔT_zone = time-zone offset, λ_obs = observer’s actual longitude and λ_std = time zone’s standard meridian. This Proposed formula tolerates the post-1883 synchronization of clocks, not as he misrepresents as a return to pre-1883 clock setting.
3. “UT1 is universal (global) time, not the local one. It is by definition the same for all inhabitants of the Earth,” quoting, it seems, from the Wikipedia misrepresentation here: https://en.wikipedia.org/wiki/Universal_Time.
The Wikipedia contributor, however, gives as first reference an article by time experts, one of whom I’ve had several conversations with since the early-80s, Dr. P. K. Seidlemann, who defines it quite differently: “Universal Time (UT or UT1) is a precise astronomical measure of the rotation of the Earth on its axis, synonymous with mean solar time at the meridian of Greenwich, sometimes known simply as Greenwich mean time (GMT),” Seago et al. (2011), Intro, second paragraph, second sentence (https://www.ucolick.org/~sla/leapsecs/seago.pdf). Dr. Dennis D. McCarthy is another time expert who I’ve had several conversations with as well since the early-80s. He says that “UT1 designates the true rotation angle of the Earth with respect to the defining fiducial point. It is the hour angle of the fiducial direction observed at longitude zero degrees” (Proceedings of the IEEE, Vol. 79, No. 7, July 1991, “Astronomical Time,” p. 916. McCarthy said here as recently as March 2024 that “We are headed toward a negative leap second … It’s a matter of when.”
In other words, it’s not a global time but a local one at the Greenwich longitude to which all other longitudes are related in a rotational sense where 1° = 4 min. of time. Saying that “Crucially, UT1 is not the local time of Greenwich or any other specific location” when UT1 (GMT) is, in fact, the LMT of Greenwich is a blatant misrepresentation!
4. “The Julian days function (jday) depends solely on UTC and is not a function of longitude.”
This is a misrepresentation because the JD calculation is based upon UT1, the reference point being Greenwich’s longitude, and UTC is a uniform atomic time scale independent of irregularities in Earth's rotation. He says UTC is more “accurate” than UT1, a “superseding of UTC,” when it’s UTC that’s aligned properly with UT1 at leap second implementation, not the reverse, so he’s tried insidiously to insert UTC into my formulas which I strongly oppose! He can’t even provide one quote from a time expert with a name who believes or has uttered such nonsense! The Swiss Ephemeris (swetest) does not even calculate the correct JD from a UTC input, which he should know if he’s an astrological programmer. The fact he’s promoting this misrepresentation is a good indication he doesn’t know!