Books on Amazon
Def Time/Feynman: it's how long we wait. It can probably not be defined any further. It is important how we measure it.
Time Measurement/Measurement: one possibility: use something that changes periodically.
History: to be able to use the day as a measure, they had to make understand that days are not always of the same length; a different instrument was needed for that, e.g. an hour glass.
But with that they had not yet proven that they are periodic! >Covariance.
We can simply say that our definition of time is based on the repetition of an obviously periodic event._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution.
Vom Wesen physikalischer Gesetze München 1993
Vorlesungen über Physik I München 2001