Since this is I’m gonna explain my question the same way.
Imagine there is a time-hating wizard who magically removes all time-keeping instruments like atomic clocks, phones and watches, so there is no way of knowing the time right now. If then we were asked to ‘bring back’ the old time that we used (e.g. so that we start again measuring 12:00 in London exactly when it was 12:00 in London before the wizard) could this be done? Is there something physical constant (like kg or meter) that determines what time of day it is? Or, did someone just say “we start measuring time from now, and I say that it is exactly 14:32…”?
Also, if there is this constant that allows us to know exactly when a certain time is, doesn’t that mean we don’t need atomic clocks and can just compare ourselves to this constant? Idk what this would be but perhaps when the sun is absolutely highest in the sky somewhere?
In: 40
In olden days they used to set the time based on the position of the sun, like a sun dial, a clock tower in the nearest town would hold the official time everyone would set their clocks after, because the earth is curved, the time would be different in one place to another, this wasn’t a problem until railways needed to be precise so they decided a standard time, precise time was also important for naval navigation. Anyways, the speed of light is a constant we know the velocity of, therefore we could set our time based on that.
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