3 ms·

I love this list, but there was one that seemed odd. "Time passes at the same speed on top of a mountain and at the bottom of a valley" Unless you're writing

I love this list, but there was one that seemed odd. "Time passes at the same speed on top of a mountain and at the bottom of a valley" Unless you're writing software used to track very intense scientific measurements requiring information about time down to the sub-nanosecond, I don't see how the effects of time dilation between a mountain and valley would ever have an effect on program logic. Everything else about time can and will bite you at one time or another.

kderbyma 3y ago
DST during a running job which crosses a boundary and upstream it is 1 hour ahead of the downstream
apocalypstyx 3y ago
Or airplane passengers vs those on the ground. Something like 59 micro-seconds per 10 million frequent flier miles.
lelandbatey 3y ago
Eh, doing the math[0], it seems like you'll actually drift about 1 nanosecond every ~35 minutes if I pick a mountain near my house vs sea level. That means you'd have about 1 microsecond of difference in your clocks in about 3 weeks. For a 1 millisecond drift though, that'd take about 66 years. That's still pretty safe, but it's definitely not "you never have to worry about this˟" territory. I'm sure some others can chime in with cases where 1 microsecond clock drift (in cases expecting very accurate clocks) can cause problems. >>> g = 9.8 c = 299_792_458 >>> h = 4392 # height of Mt. Rainier >>> drift_per_second = (g*h)/(c**2) >>> print(drift_per_second) 4.789023865263744e-13 >>> nanosecond = 1.0e-9 >>> seconds_to_drift_one_ns = nanosecond / drift_per_second >>> print(seconds_to_drift_one_ns) 2088.1081993625176 >>> print(seconds_to_drift_one_ns / 60) # minutes till a 1 ns drift accumulates 34.80180332270863 >>> print((seconds_to_drift_one_ns * 1000) / 60 / 60 / 24) # days till ~1 microsecond accumulates 24.167918974103213 [0] - http://www.leapsecond.com/great2016a/#%3A~%3Atext%3DConceptually%2C%20the%20experiment%20is%20very%2Cthe%20clocks%20should%20still%20agree http://www.leapsecond.com/great2016a/#%3A~%3Atext%3DConceptu...

kderbyma 3y ago

DST during a running job which crosses a boundary and upstream it is 1 hour ahead of the downstream

apocalypstyx 3y ago

Or airplane passengers vs those on the ground. Something like 59 micro-seconds per 10 million frequent flier miles.

lelandbatey 3y ago

Eh, doing the math[0], it seems like you'll actually drift about 1 nanosecond every ~35 minutes if I pick a mountain near my house vs sea level. That means you'd have about 1 microsecond of difference in your clocks in about 3 weeks. For a 1 millisecond drift though, that'd take about 66 years. That's still pretty safe, but it's definitely not "you never have to worry about this˟" territory. I'm sure some others can chime in with cases where 1 microsecond clock drift (in cases expecting very accurate clocks) can cause problems. >>> g = 9.8 c = 299_792_458 >>> h = 4392 # height of Mt. Rainier >>> drift_per_second = (g*h)/(c**2) >>> print(drift_per_second) 4.789023865263744e-13 >>> nanosecond = 1.0e-9 >>> seconds_to_drift_one_ns = nanosecond / drift_per_second >>> print(seconds_to_drift_one_ns) 2088.1081993625176 >>> print(seconds_to_drift_one_ns / 60) # minutes till a 1 ns drift accumulates 34.80180332270863 >>> print((seconds_to_drift_one_ns * 1000) / 60 / 60 / 24) # days till ~1 microsecond accumulates 24.167918974103213 [0] - http://www.leapsecond.com/great2016a/#%3A~%3Atext%3DConceptually%2C%20the%20experiment%20is%20very%2Cthe%20clocks%20should%20still%20agree http://www.leapsecond.com/great2016a/#%3A~%3Atext%3DConceptu...