Comment by whoknowswhat11 | Hacker News Reader

Comment by whoknowswhat11 | Hacker News Reader

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If you need it you can do something around -12+.

Is this needed for the clock drift in the CC hand terminal that creates these "clock sync" errors that make it so the bank can't figure out my balance / avoid an overdraft?

There is digital radio time code, there is the internet and NTP where you can pull directly from the atomic clock standard, there is GPS. You can get your own atomic clock and get by for a while even IF you need some kind of perfect sync so the credit card reader doesn't have a "clock sync" error.

The claim here is apparently that relatively insane levels of percision are needed so that normal database transactions remain atomic. That I can withdraw cash from an ATM. That I can use my credit card.

I remain skeptical. Withdrawing from an ATM depends on ONE system knowing what your balance is. Your banks. While it might be nice to be accurate to the microsecond, it's not a requirement. To the second is going to be fine. Similarly, when you swipe a credit card, the auth process does a live inquiry (balance, fraud control etc). Again, I'm extremely skeptical of the claims here that we need microsecond SYNCED time for any of this.

The thing is, once something becomes commonplace, people build in obligations against it without thinking about it. All those layers that civilization depends upon have a cost, and as long as the cost is paid, all is good.

We're talking about the sudden loss of precision timekeeping, which could desync all sorts of things in unexpected ways. It's my understanding that precision time is required to make even the cell phone networks properly operate, and they'd fall apart without it.

If Russia were to take out GPS, the effects would be deep and expensive to correct, if we could. There's a very small, but non-zero chance it could collapse our supply chains. As time goes on, this chance grows, unless there is an active effort to keep backup systems viable. We all know how actively the US maintains infrastructure 8(

The claim was about ATM withdrawals and credit card swipes. Ie, without a GPS clock there would be a "clock sync" error in the ATM machine, and no cash could be drawn.

I continue to remain EXTREMELY skeptical of this claim. It makes almost no sense.

Please note that GPS is not the source of time, NIST is, and you can get NIST time in a variety of ways including over the internet if needed. And as I have been describing, many of these described errors are around systems with one source of truth (ie, not google spanner type globally distributed databases). So they make even less sense.

Note I'm familiar with clock skew issues and errors in authentication and other systems. These issues show up when errors are in minutes and seconds not microseconds.

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