5 ms·
If I am asking for how many seconds since 1970, I'm literally asking for that, as if someone stood with a stopwatch (not a cellphone clock!) How you want to dis
by ikekkdcjkfke 2y ago
If I am asking for how many seconds since 1970, I'm literally asking for that, as if someone stood with a stopwatch (not a cellphone clock!)
How you want to display that in various timezones i do not care
- defrost 2y agoWhich specific stopwatch? Why don't you care about that stopwatch's drift over the past 50 years, the tempreture related variation, the errors induced by motion, air pressure and humidity? Would you prefer a count that's averaged over many from the same manufacturer, or from many over many manufacturers?
- 01HNNWZ0MV43FF 2y agoSwitch to TAI + fixed offset I just don't give a damn whether solar time is a couple minutes off of calendar time. Seconds should be seconds. Solar time is a human construct, it shouldn't affect computers.
- defrost 2y agoThe person I responded to was interested in 50 years of seconds from a stopwatch. That's a mechanical device with multiple sources of error and a need to be wound regularly. The questions I asked are about common sources of drift in mechanical watches and wether or not they cared enough to attempt to account for them.
- icehawk 2y agoYou're conflating the term "stopwatch" with an all mechanical device. That wasn't even true at the time period specified-- the quartz movement had been created in the 1950s and the first quartz pocket watch had been introduced in the mid 1960s. The issues you bring up are only relevant to a particular set of devices that can be used as timepieces that measure the amount of time that elapses between its activation and deactivation-- and are are all stopwatches.
- withinboredom 2y agoWhat is so special about thailand's timezone?
- kuschku 2y agoTAI not as in thailand, but TAI as in temps atomique international: https://en.wikipedia.org/wiki/International_Atomic_Time https://en.wikipedia.org/wiki/International_Atomic_Time
- withinboredom 2y agoI just tried to get a time in the TAI timezone via my programming language and it doesn't exist. Not a very useful timezone.
- hansvm 2y agoYou can wrap libtai in almost any language, and that's been done for the bigger ones. Which language are you using, and why is the conclusion not that the language is deficient?
- withinboredom 2y agoMaybe it should be added to the OS instead of a library? Why would I use a library for a timezone?
- hansvm 2y agoMaybe that's a fun new OS feature. If somebody wants to try it, more power to them. Answering your question more directly though, why would you want it in an OS? The OS primarily exists to mediate shared resources, and to a slightly lesser degree to sensibly wrap shared code everyone is definitely using (e.g., chrome and hacker news don't have to care about my LCD driver). What exactly do you gain by baking TAI into the OS? You lose in update availability, OS install size, application-specific customizability, runtime performance of TAI function calls, .... You'd want to gain something for those costs. > Why would I use a library for a timezone? Most people do? Even libc localization isn't a part of the OS (and is fraught with issues; never use libc localization), and that's the most primitive timezone library most people use. Everything else is baked into their language runtime or a third-party like nodatime. TAI isn't special in that regard.
- saulpw 2y agoA cesium stopwatch: https://en.wikipedia.org/wiki/Caesium_standard https://en.wikipedia.org/wiki/Caesium_standard
- cobbal 2y agoHow deep in a gravity well are you planning to keep this cesium stopwatch?
- Elucalidavah 2y agoExactly at the point of Null Island at the epoch, of course. Or, in practice, as close an approximation as can be calculated by now.
- defrost 2y agoFun reference, although in that spirit it appears that Null Island at mean sea level for that point might be as much as 22m vertical separation from true 1G Geoid. https://en.wikipedia.org/wiki/Geoid#/media/File:Geoid_undulation_10k_scale.jpg https://en.wikipedia.org/wiki/Geoid#/media/File:Geoid_undula... Approximations are pretty easy until you get into the details, dammit.
- defrost 2y agoNot at all what was asked for; not available as a handheld stopwatch someone could stand with in 1970 ... and I'm doubtful there's such a thing available today. Works if you don't mind a lab bench full of equipment, but doesn't appear to match the specification of the request. Still, thanks for your input.
- wolfendin 2y agoHandheld was never specified directly, just “stood with a” which can just mean “next to.” The HP 5061 was introduced in 1964, why do you think a counter that can reference the frequency standard is not possible? You might want to be more rigorous about reading specifications.
- afiori 2y agothe TAI stopwatch, the earth surface is relativistally uniform enough that averaging good clocks gives a good enough clock for almost any practical purpose.
- zokier 2y agoUTC doesn't stop us from having that, UTC seconds tick at SI rate. The thing that makes UTC special is that minutes might have 59-61 seconds each. But if you have stopwatch just counting seconds then leap seconds do not make any difference at all, and UTC and TAI are effectively the same.
- t_mann 2y agoIn that case I suppose you'll need to find yourself a universe with different physics from ours...
- xelxebar 2y agoYou speak of time as if it's some directly measurable quantity. Instead, all we have are periodic quantities of various (messy) physical processes or sampling methods thereof relative to certain underlying models: - _TAI_: Sampled average of ticks in the (very noninertial) frame of the surface an implicitly-defined idealized rigid Earth. Each tick is further a sampled approximation of our definition of a second, which invokes idealizations at absolute zero. - _UT1_: Mostly the same frame as TAI. Each tick is considered a sample, trying to measure the "true rotation" of some idealized rigid Earth, module any geophysics. Note, the definition invokes quite sophisticated models of celestial mechanics, and explicitly ignores certain kinds of "high frequency perturbations". - _UTC_: Based on UT1, but take into account some basic, empirically-measured geophysical processes. Depending on the particular physical processes, models, and sampling methods you choose, the quantity you get for "seconds since 1970" will be different, and there will be (complicated) relationships for how each of those processes transform tick counts between each other. In some cases, the transformations will be a priori impossible, only permitting approximations under simplifying assumptions. IMO, the remarkable thing is that the various ticks all line up as well as they do, which is why we can mostly get away with treating all these as a single unified Ticking Time concept. On the other hand, I also think the various standards do a reasonable job delineating messy reality into potentially useful tick-producing processes and the systems needed to make those practically useful. As a software engineer, the lesson for me is that I can't always ask "what time is it?", "how long has it been?", or "which came first?" Instead, we I may need to shift focus onto different invariants in the problem I'm trying to solve.
- afiori 2y ago> As a software engineer, the lesson for me is that I can't always ask "what time is it?", "how long has it been?", or "which came first?" If we were using TAI instead of UTC we very easily could.
- xelxebar 2y agoReally? TAI cannot locate historical dates indefinitely. TAI doesn't even make sense on timescales that exceed Earth's lifetime. It doesn't encode enough information to answer questions about elapsed time of even ideal clocks at real, physical locations to arbitrary precision. Fast enough operations on a distributed database can exceed the precision limits of TAI's definition, making it impossible to canonically order events.