5 ms·

Because its reliability is happenstance.

zaarn 9y ago
No it's standardized. Outside of accidents the power providers take extreme care to keep the frequency synchronized to UTC. Exactly. A clock using the power grid as reference might be off by 4 minutes over the day but on average it will be perfectly on time.
- wglb 9y ago
  It used to be in the US that some operators would have a plain off-the-shelf alarm clock in the control room, and, in case the evening load made the frequency dip, operators would adjust things so that the clock would read 6am (for example) exactly the next day.
Piskvorrr 9y ago
Nope. There's man-years of effort per day in keeping it reliable; as evidenced by the point that it takes major political meddling over a prolonged period to throw it off, and an article on HN for people to even notice "it has been acting sort of weird, now that you mention it". "I didn't notice until now" is quite the opposite of happenstance, on par with the PHB mantra "what do we need devops for, anyway, the network seems to be up!" Well it's up because devops is keeping it up. Likewise, the grid doesn't just magically self-balance around 50 Hz.
- gpvos 9y ago
  I definitely noticed this in the last few weeks already, since my alarm clock is set to switch the radio on in the half minute before the news on the top of the hour. I was already searching for reasons, and I would have expected an announcement about this a lot sooner.
- spdionis 9y ago
  I mean, in software engineering we try to avoid unnecessary dependencies right? This is exactly what's happening, why would those clocks ever depend on the power grid?? EDIT: Nevermind, sounds like there are precision concerns that justify using the power grid for timekeeping.
  - LaGrange 9y ago
    > I mean, in software engineering we try to avoid unnecessary dependencies right? I/you wish.
  - Piskvorrr 9y ago
    Indeed. There's a tradeoff in both directions - either you trust the cloud^W grid, or you trust your local clock, and both of them have failure modes; there's no one clearly superior option here. You could combine them, but then it gets complex in short order.
  - baq 9y ago
    > in software engineering we try to avoid unnecessary dependencies leftpad would like to have a word
    - Piskvorrr 9y ago
      Putting Lego blocks together is engineering now? Edit: NPM has engineering challenges, and Node as well...but I would be extremely hesitant to call a library of ~ten LoC "engineering."
      - baq 9y ago
        i'm not a fan of what the JS ecosystem looks like, but you can and will get bitten by transitive dependencies if you don't store them all in a local mirror that doesn't respect upstream deletions...
        Piskvorrr 9y ago
        Of course. But that's an engineering problem worthy of the name (cache-invalidation and whatnot).
oldcynic 9y ago
Grids ensure the cycle count is correct over the day. There will be some drift from spikes and peak loads, but they adjust the frequency to compensate. They have atomic clocks, for the EU grid it's in Switzerland, to track the cycle count. UK and EU grids have websites letting you look at frequency history. There's still an awful lot of infrastructure keyed off having an accurate synchronous time, including billing systems, traffic lights, street lights...

No it's standardized. Outside of accidents the power providers take extreme care to keep the frequency synchronized to UTC. Exactly. A clock using the power grid as reference might be off by 4 minutes over the day but on average it will be perfectly on time.

wglb 9y ago
It used to be in the US that some operators would have a plain off-the-shelf alarm clock in the control room, and, in case the evening load made the frequency dip, operators would adjust things so that the clock would read 6am (for example) exactly the next day.

Piskvorrr 9y ago

Nope. There's man-years of effort per day in keeping it reliable; as evidenced by the point that it takes major political meddling over a prolonged period to throw it off, and an article on HN for people to even notice "it has been acting sort of weird, now that you mention it". "I didn't notice until now" is quite the opposite of happenstance, on par with the PHB mantra "what do we need devops for, anyway, the network seems to be up!" Well it's up because devops is keeping it up. Likewise, the grid doesn't just magically self-balance around 50 Hz.

gpvos 9y ago
I definitely noticed this in the last few weeks already, since my alarm clock is set to switch the radio on in the half minute before the news on the top of the hour. I was already searching for reasons, and I would have expected an announcement about this a lot sooner.
spdionis 9y ago
I mean, in software engineering we try to avoid unnecessary dependencies right? This is exactly what's happening, why would those clocks ever depend on the power grid?? EDIT: Nevermind, sounds like there are precision concerns that justify using the power grid for timekeeping.
- LaGrange 9y ago
  > I mean, in software engineering we try to avoid unnecessary dependencies right? I/you wish.
- Piskvorrr 9y ago
  Indeed. There's a tradeoff in both directions - either you trust the cloud^W grid, or you trust your local clock, and both of them have failure modes; there's no one clearly superior option here. You could combine them, but then it gets complex in short order.
- baq 9y ago
  > in software engineering we try to avoid unnecessary dependencies leftpad would like to have a word
  - Piskvorrr 9y ago
    Putting Lego blocks together is engineering now? Edit: NPM has engineering challenges, and Node as well...but I would be extremely hesitant to call a library of ~ten LoC "engineering."
    - baq 9y ago
      i'm not a fan of what the JS ecosystem looks like, but you can and will get bitten by transitive dependencies if you don't store them all in a local mirror that doesn't respect upstream deletions...
      - Piskvorrr 9y ago
        Of course. But that's an engineering problem worthy of the name (cache-invalidation and whatnot).

oldcynic 9y ago

Grids ensure the cycle count is correct over the day. There will be some drift from spikes and peak loads, but they adjust the frequency to compensate. They have atomic clocks, for the EU grid it's in Switzerland, to track the cycle count. UK and EU grids have websites letting you look at frequency history. There's still an awful lot of infrastructure keyed off having an accurate synchronous time, including billing systems, traffic lights, street lights...