29 January 2022 | New Scientist | 35What day is it?
It seems like a simple matter, but working out the time depends
on both history and technology, finds George BassBook
A Brief History of
Timekeeping: The science
of marking time, from
Stonehenge to atomic clocks
Chad Orzel
Oneworld Publications
HOW did humans progress
from measuring time with
stone solstice markers to a
smart watch on which it is also
possible to read this review?
In A Brief History of Timekeeping,
Chad Orzel, physicist and author
of bestselling book How to Teach
Quantum Physics to Your Dog,
turns his enthusiasm for time
travel to something more tangible:
how humans through the ages
have measured the passage of time.
It may seem like being ruled
by the clock is a relatively recent
phenomenon, but Orzel argues
that it has been “a major concern
in essentially every era and location
we find evidence of human activity”.
Thanks to a 1960s excavation
of a site in east Ireland, for example,
we know that the 5200-year-old
tomb Newgrange was built by
people with enough astronomical
knowledge to create an opening
that focuses a shaft of light onto
the back of the chamber at sunrise
on the winter solstice.
Knowledge of the movement of
stars remains important today in
our understanding of time, says
Orzel. It explains, for instance,
why religious holidays change dates
from year to year. Yet the calendar is
also a social construct, representing
a delicate balancing act between
stellar movement, bureaucracy,
ritual and religion. The overnight
jump from Wednesday 2 September
to Thursday 14 September when
Great Britain adopted the Gregorian
calendar in 1752 is a case in point.
Orzel’s enthusiasm for the
past is balanced by his disdain for
modern misconceptions around
time. He admonishes the flat-Earth
conspiracy theory that has been
promoted by celebrities like
basketball player Kyrie Irving,
and the way it disrupts geography
and astronomy lessons in schools.
He also laments how the
passing aeons often only become
of interest to the public when they
have something dramatic to say,
such as the widely shared Mayan
prophecy that the world would end
on 21 December 2012. This was
based on a fundamental misreading
of the Mayan calendar system, says
Orzel, who concedes that at least
it made people more aware of
the Mayans’ pioneering base-20
numerical system.
Throughout the book,
Orzel scoots backwards and
forwards in time, treating us
to illustrations of spectacular
forgotten timepieces. He explains
how Athenian water clocks were
used to limit speaking time in law
courts, how a 12th-century Chinese
water tower designed by Su Song
became the basis for the modernmechanical clock, using a system
of scoops, bronze spheres,
counterweights and – crucially –
a numbered face. Rod-based
verge-and-foliot clocks followed
in its wake, and Orzel details how
these gave way to the pendulum,
which reduced the number of
missed ticks per day from several
hours’ worth to just minutes.
The author’s enthusiasm doesn’t
wane as he moves into the digital
era, explaining how quartz-based
wristwatches “democratised” time
and serve as temporal “tuning forks”
for the masses, before exploring
how many of our modern devices
sync up with caesium atomic clocks
for the latest word in punctuality.
He also ponders how tomorrow’s
quantum computers may prompt
physicists to argue for the
decimalisation of time. This has been
attempted before, most recently by
19th-century French polymath Jules
Henri Poincaré, who argued for
splitting the day into 100 minutes
made up of 100 seconds. This would
be confusing for a generation or so,
but as Orzel’s book makes clear,
time, and its measurement, stands
still for no one. ❚George Bass is a writer
based in Kent, UKNewgrange tomb is a Neolithic
site in Ireland that is accurately
aligned to mark the winter solsticeSHUT
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