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Europe pushing for lunar time zone

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Re: Europe pushing for lunar time zone

#291

Post by lolinder »

dylan604 wrote: post #289
aerophilic wrote: post #284

Earlier quoted context omitted.

This is interesting… and I wonder how this plays out across different planetary bodies. It effectively means how we define a second will be different across the board. Can anyone weigh in on whether the MKS standard of a second is based on something in free space, or here on earth? If universal (based on free space) Would this mean we should all convert to/from this second, and treat our own second as relative?

"The second [...] is defined by taking the fixed numerical value of the caesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1.[1]" https://en.wikipedia.org/wiki/Second so unless caesium behaves differently at different locations in the universe, this definition should be pretty uniform.

Cesium on the moon would continue to have the same frequency on the moon, but a cesium clock on the moon would run 56 microseconds fast per day relative to an identical clock on earth, because time itself moves differently.

Re: Europe pushing for lunar time zone

#292

Post by r2_pilot »

dylan604 wrote: post #289
aerophilic wrote: post #284

Earlier quoted context omitted.

This is interesting… and I wonder how this plays out across different planetary bodies. It effectively means how we define a second will be different across the board. Can anyone weigh in on whether the MKS standard of a second is based on something in free space, or here on earth? If universal (based on free space) Would this mean we should all convert to/from this second, and treat our own second as relative?

"The second [...] is defined by taking the fixed numerical value of the caesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1.[1]" https://en.wikipedia.org/wiki/Second so unless caesium behaves differently at different locations in the universe, this definition should be pretty uniform.

So I'm not an expert, but this behavior actually would behave differently in different gravity wells. Due to relativity, while you would observe a cesium clock working normally on the moon, your Earth buddy would disagree with your clock because the buddy would be down in a larger gravity well.

Re: Europe pushing for lunar time zone

#293

Post by yencabulator »

dylan604 wrote: post #289
aerophilic wrote: post #284

Earlier quoted context omitted.

This is interesting… and I wonder how this plays out across different planetary bodies. It effectively means how we define a second will be different across the board. Can anyone weigh in on whether the MKS standard of a second is based on something in free space, or here on earth? If universal (based on free space) Would this mean we should all convert to/from this second, and treat our own second as relative?

"The second [...] is defined by taking the fixed numerical value of the caesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1.[1]" https://en.wikipedia.org/wiki/Second so unless caesium behaves differently at different locations in the universe, this definition should be pretty uniform.

That's the whole point, it does. Or, said differently, it behaves the same in whatever reference frame it's in, but observers in other reference frames can observe it being slower or faster.

Here's an example with very elementary particles, muons:

https://phys.libretexts.org/Bookshelves/University_Physics/B...

Re: Europe pushing for lunar time zone

#294

Post by Diggsey »

aerophilic wrote: post #284
lolinder wrote: post #276

> There are also technical issues to consider. Clocks run faster on the moon than on Earth, gaining about 56 microseconds each day, the space agency said. Further complicating matters, ticking occurs differently on the lunar surface than in lunar orbit. At first this sounded like they were describing a mechanical issue with analog clocks, but they're not: time on the moon actually moves this much faster relative to E…

This is interesting… and I wonder how this plays out across different planetary bodies. It effectively means how we define a second will be different across the board. Can anyone weigh in on whether the MKS standard of a second is based on something in free space, or here on earth? If universal (based on free space) Would this mean we should all convert to/from this second, and treat our own second as relative?

It doesn't really work like that: a second is a second anywhere in the universe, but time at different places in the universe doesn't progress at the same rate.

ie. the issue is not with how we define the second. The issue is expecting that if two people in different frames of reference wait for one second, that they will continue to be "synchronised".

In fact it's worse than that, it's impossible to even define the concept of "synchronisation" for entities in different locations. You can only know that two things are synchronised if they are in the same location.

If the two entities are in the same frame of reference (ie. not moving or accelerating relative to each other) then you could argue that you just send a beam of light there and back, and assume the light takes the same time in each direction in order to synchronise... But we don't even know that light travels at the same speed in all directions! We've never been able to measure the "one-directional" speed of light, we can only measure the round-trip, so for all we know light could have a preferred direction in the universe and travel faster in that direction, as long as it is the same amount slower in the other direction. We would never be able to tell.

Re: Europe pushing for lunar time zone

#295

Post by BeFlatXIII »

WastingMyTime89 wrote: post #132
sen wrote: post #106

Earlier quoted context omitted.

I was so convinced .beats would take over the world (or solar system in this case). I had their watch, I installed their task-bar clock plugin for Windows 98, I harped on about it to my friends... a surprising number of which actually agreed it was a good idea. Then it just kinda fizzled out. I'm still upset it didn't take off.

It didn’t work in 1793 when it was mandated by the Convention despite the rest of the metric system taking roots. It was unlikely that a rebrand by a greedy Swiss corporation would make it more popular. Plus, current time keeping already use superior base systems. 12 and 60 are both highly composite numbers. Using a decimal system would be a step back. I wish we had symbols for 10 and 11 however.

I still have a Decimal time app on my phone, though. My Mac, too, thanks for Catalyst.

Re: Europe pushing for lunar time zone

#296

Post by riffic »

lolinder wrote: post #276

> There are also technical issues to consider. Clocks run faster on the moon than on Earth, gaining about 56 microseconds each day, the space agency said. Further complicating matters, ticking occurs differently on the lunar surface than in lunar orbit. At first this sounded like they were describing a mechanical issue with analog clocks, but they're not: time on the moon actually moves this much faster relative to E…

correct me if I'm wrong but aren't relativistic differences due to velocity and not gravity differences?

Re: Europe pushing for lunar time zone

#297

Post by dan_mctree »

How about just picking a non-cyclical time? Just count the amount of seconds/milliseconds since 1 Jan 1970 where the duration of the second is synced to those on earth. Just have no official days/hours/years whatever, no leap seconds, no adjustments, no nothing. Those details can be filled in at will by whoever needs lunar time for daily use.

Re: Europe pushing for lunar time zone

#298

Post by yencabulator »

jxf wrote: post #267
patife wrote: post #261

Earlier quoted context omitted.

what's the different exactly @jxf?

A reference time describes what standard of time we use. On Earth, for most human use cases, the reference time is UTC. UTC is measured by using International Atomic Time (TAI, from the French "temps atomique international") and adding or subtracting a prescribed number of leap seconds to account for the rotation of the Earth. We don't use TAI in everyday use because it's constantly and continuously changing in small…

> We don't use TAI in everyday use because it's constantly and continuously changing in small ways to account for the tiny accelerations or decelerations in Earth's rotation, and that's annoying for computers. So instead we use UTC.

Wait, what? TAI is the one time standard that doesn't change. It's just a bunch of atomic clocks averaged together. As monotonic as human kind is able to manufacture, at this time.

UTC is TAI+varying offset in an effort to stay close to mean solar time.

The varying offset of UTC, called leap seconds, is what's annoying to computers. If we ran computers on TAI, they would be simpler!

And "data center time" tends to be something approximating UTC, with leap seconds smeared into continuous adjustments, just because UTC is annoying to computers.

https://en.wikipedia.org/wiki/International_Atomic_Time

https://en.wikipedia.org/wiki/Coordinated_Universal_Time

https://en.wikipedia.org/wiki/Solar_time#Mean_solar_time

Re: Europe pushing for lunar time zone

#299

Post by wasmitnetzen »

Tor3 wrote: post #250
zvr wrote: post #220

Earlier quoted context omitted.

I cannot imagine a world where "the norm" of human interaction would be with people in other times zones.

Huh? For me it is, and has been like that for a very long time. I work with various customers throughout the day, and they are in various different timezones. When I'm not working I almost daily interact with family, again different timezone. I am always aware of various timezones.

Is this the norm for those people too, or are you basically the only one they ever talk to where timezone matters?

Re: Europe pushing for lunar time zone

#300

Post by runarberg »

riffic wrote: post #296
lolinder wrote: post #276

> There are also technical issues to consider. Clocks run faster on the moon than on Earth, gaining about 56 microseconds each day, the space agency said. Further complicating matters, ticking occurs differently on the lunar surface than in lunar orbit. At first this sounded like they were describing a mechanical issue with analog clocks, but they're not: time on the moon actually moves this much faster relative to E…

correct me if I'm wrong but aren't relativistic differences due to velocity and not gravity differences?

Both

https://en.wikipedia.org/wiki/Gravitational_time_dilation

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