"the base unit of time in the International System of Units that is equal to the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom"
@Melissabeartrix
I was listening to the Dr Karl podcast the other day and he said the most accurate clocks these days are so good that in the time that the universe has existed they would have lost less than a second.
@Melissabeartrix@SeanHawley Of course, this brings up the question of accuracy...which is more accurate, a stopped clock which shows the correct time twice a day; or a clock running slow which never shows the correct time? 😉
A mate who sailed was asked by another sailor for the coordinates of a particular river entrance, which became a problem because their GPSs were using different co-ordinate systems!
Similarly I was working as a geologist for the state govt in the 90s when we were mapping in collaboration with federal govt geologists. This lead to problems because each govt dept worked off different co-ordinate systems. This was also during the Iraq? war when the US was corrupting GPS data accuracy.
@NormanDunbar
Things have probably changed since the 90s and phones etc possibly run off a globalised co-ordinate system???
But from memory co-ordinate systems involved a geoid which defined the locally idealised model of the shape of the earth and then the map systems under that which defined the conversion from 3d globe to 2d map surface. But that could be wrong.
Because the earth isn't a perfect sphere you chose the system that is most accurate locally.
I think we worked with the Australian Map Grid 1984 based on a particular geoid. I believe there was a transition going on to a new geoid/map grid at the time hence govts using different systems.
@SeanHawley@Melissabeartrix Interesting. Thanks again. It appears, if I've read it properly, that the current standard, WGS24, is accurate to 2cm and is global. (I think!!!)
@Melissabeartrix
My job requires that the time of various processes starting, stopping, etc be recorded using cheap analogue clocks and digital displays on very expensive machinery.
The very expensive machinery time display drifts much worse than the cheap analogue clocks ... until the batteries drain.
That would be due to the Hz of the power ... So it's either counting 50 or 60 Hz ... Depending on country Australia is 60 hz {?} ... Because it's such a low number you get more errors ... Also the power generators do slow the Hz up and down depending on load
Another thought while typing is a very rubbish time circuit fitted into the machine
Add comment