Dispute accuracy of History section Dispute accuracy of article The claim in the History section introduced by User 156 61 250 250 that GMT is defined as UT1 is not true As Bernard Guinot writes in the abstract of his paper The International Conference held in 1884 at Washington defined a universal time as the mean solar time at the Greenwich meridian GMT Now the Universal Time version UT1 is strictly defined as proportional to the angle of rotation of the Earth in space In this evolution the departure of UT1 from GMT does not exceed one or two seconds Clearly there can not be a departure between two time scales if they are defined to be the the same