Get rid of political time-zones and DST and simply define 6:00am to be sunrise world wide. Each day starts at 6am and counts from there.
(If you are really brave let the length of the hour vary by latitude so that sunset is always at 6pm as well. In the winter up north the night hours are simply longer than the daylight hours. But this is too enlightened I think.)
We have the tech to do this. The first one is very practical. What time is it? How many hours since sunrise in this location +6?
@futurebird We already have the code to handle the second one:
JS version:
https://github.com/hebcal/hebcal-es6/blob/main/src/zmanim.ts#L226
Golang version:
https://github.com/hebcal/hebcal-go/blob/main/zmanim/zmanim.go#L141
References:
https://hebcal.github.io/references.html
(Originally written in Emacs Lisp in the 80s (possibly, tho maybe this was just dates and zmanim came later), because of COURSE it would have been initially written by a Emacs users who eLSE)
(Heavily used by people in every Jewish community I've been part of as https://www.hebcal.com .)
(There's also https://www.myzmanim.com , so at least two implementation out there -- tho that one's proprietary.)
@futurebird A subtle detail you missed that's needed for both systems, though -- you need both latitude AND elevation.
Also we don't have any implemented (or possibly: any particularly clean halachic) solution for when you get to high enough latitude. The math sorta falls apart there:
https://www.hebcal.com/shabbat?geo=geoname&geonameid=2729907&zip=
https://www.myzmanim.com/day.aspx?askdefault=1&vars=86672323&q=murmansk
@futurebird Also, the people who are mentioning Trains! as an objection should watch Unrueh (2022).
It won't argue against them or change their opinion in any way, it's just directly tangentially relevant to specifically the topic of community timekeepings and trains,
and is a good movie.
myrmepropagandist
Gadfly (-booq-)