46 | New Scientist | 1 January 2022
Features
Clock watchers
We use them to measure time’s passage, but now it seems
a closer look at clocks could transform our understanding
of the fourth dimension, says Miriam Frankel
A
CENTURY ago, two intellectual giants
met to debate the nature of time. One
was the French philosopher Henri
Bergson, a superstar whose fans caused the
first traffic jam on Broadway in New York as
they flocked to one of his earlier appearances.
He believed there was more to time than
something that can be measured by clocks,
captured by mathematics or explained by
psychology. He argued that the way we
experience it, with a duration and direction,
could only be revealed through philosophy.
Bergson’s opponent, a physicist called
Albert Einstein, disagreed. After developing
his theories of relativity he believed time
was a physical entity, separate from human
consciousness, that could speed up or slow
down. Einstein thought that time was
interwoven in space in a static cosmos
called the block universe which lacks a
clear past, present or future.
Almost 100 years later, the question of why
the time we perceive is so different from the
time postulated in physics is still hotly debated.
Now, fresh clues are starting to suggest the
devices we use to measure time might be
crucial to arriving at an answer.
Those clues relate to the fact that in general
relativity, clocks are incorporated into thetheory as perfectly idealised objects, with
smooth readings that are accurate no matter
how much you zoom in, when they actually are
anything but. “Clocks are physical things which
are made up of physical systems, and so we
kind of know that idealisation can’t be right,”
says Emily Adlam at the Rotman Institute of
Philosophy at Western University in Canada.
“A more realistic understanding of clocks may
ultimately be the key to understanding time.”
We can measure time using anything that
goes through a change – sundials use the
shifting sun, water clocks tap the flow of water
and even the temperature of a cup of tea can
help us estimate when it was brewed. Today,
we mostly use sophisticated mechanical and
atomic clocks, which can measure time much
more accurately than a cup of tea, because
they tick reliably with a certain frequency.
Since astronomer Christiaan Huygens
invented the first pendulum clock in the
17th century, we have been steadily improving
the accuracy of scientific clocks, with
phenomenal results. Nowadays, the most
impressive machines can measure each
second so accurately that they wouldn’t miss
a beat in 20 billion years, longer than the age
of the universe. Impressive. But it turns out
there may be a price to pay for such accuracy. HARDZIEJ STUDIO