How do we actually know what the time is? Is there some “master clock” that all time zones are based on? And if so, what does THAT clock refer to?

Question

EDIT: I believe I have kicked a hornet’s nest. Did not expect this to blow up! But I am still looking for the “ur time”. the basis for it all. Like, maybe the big bang, or something.

In: 5399

Answer 1

I think the less satisfying answer is that GMT (Greenwich Mean Time), made popular during the rise of rail travel, was landed on – it is noon GMT when the sun is directly above the Royal Observatory in Greenwich. From here, the eventual move to measuring cesium decay now “keeps us true” (accounting for leap years/seconds and the ever-changing rotation of the earth) to the time someone decided was accurate when GMT was introduced. And we just roll with it.

Then we’ve generally accepted both the current year (2023) and a Gregorian calendar with twelve months – allowing us to know the time of the day of the year, wherever we are. So, we (no one in particular but the various people in positions of influence along the way) “just decided”.

Time is accurate right now because we say it is!

Least that’s how I understand it…