Question

why GMT was chosen for time reference ?

Answer 1

It was chosen because of the astronomical observatory located at Greenwich, which could accurately measure the hour of the day (that is mean solar time)

Answer 2

the G.M.T. is wherethe meridian passes through,and is the standard reference to calculate all other time difference from,and everything else is calculated around it.

Answer 3

Two main reasons, one scientific, the other political. The scientific one is that there was an astronomical observatory there, able to accurately determine the time of day from the sun angle. the second political, is that Britain became a maritime empire, so enforced its longitude system (which depends upon time) upon the rest of the world. before GMT, the prime meridian was centred in Paris.

It is also taken as a standard reference sicne accurate measurement of time from a reference point is required to calculate ones longitude