The added hour of sleep gifted to us this weekend was no doubt welcomed by you all. It was first introduced in the UK in 1916 due to the work of the then late William Willett as it better aligns our time with the natural daylight hours in which the sun is up during the winter. This arbitrary adjust of time highlights the nature of time as a social construct that is maintained by us for convenience and social interaction.


The history of unified time begins with the Greenwich Mean Time (GMT) in the 19th-century to allow for the creation of train timetables in the UK. This led to time zones across the globe to help with trade and navigation. But the drawing up of time zones appears at time to be quite random and has even been politicised. Spain occupies the same longitudes as the UK, yet it is one hour ahead on European time. This was adopted in World War II during the Franco regime as a display of their political alignment with Germany and this has simply remained.


The measurement of time to align with the sun goes back much further than this with the use of sundials and the most accurate example of this are meridian sundials. These sundials are a fine line across which the sunlight will cross exactly at the solar noon. These were used to set manual clocks to for local time. But this measurement is inaccurate as the sundial relies upon the speed of the sun’s movement across the sky to be constant. This is untrue due to the Earth being in an elliptical orbit and the tilt of the Earth’s axis.


The current most accurate form of time keeping are atomic clocks that use the repeating signal of electrons in atoms emitted when they change energy levels. But even this is not perfect and scientists at the International Earth Rotation and Reference Systems Service still look to the sky at distant quasars and calculate their position to determine the adjusts needed to our time in order to maintain its alignment with natural daylight, which they do with ‘leap seconds’.


Physics applicants can study the calculations required to recognise changes in distant quasars placement in the sky. HSPS and Philosophy students can consider the social purpose of time and the need for accuracy in modern society.

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