Physicists at the University of Oxford in the UK have conducted an experiment that suggests the more accurately clocks tick, the more disorder, or entropy, occurs in the universe.
The second law of thermodynamics states that over time, entropy increases. This means that there was less entropy in the past than we can expect in the future. This rule, also known as the ‘arrow of time’, is one of the few quantities in physics that puts time in a particular direction.
A unidirectional concept of time explains many things observable by the naked eye. For example, it explains why it is easier to mix ingredients than separate them. It also explains why watching a video in reverse produces images that feel foreign to us, for example, watching a fire shrink into a matchstick.
Previously, scientists were able to show that tiny quantum clocks, a type of atomic clock involving laser-cooled atoms that jump at regular intervals, create more entropy the more accurately they tick. Proving that larger, more complex clocks also produce more entropy when ticking more accurately has been difficult to prove until now.
"Clocks are in some way like little steam engines — you need to put work [energy transfer needed to make mechanical devices run] into them to measure time," says Natalia Ares, one of the study's authors. "In order to get that regular tick, tick, tick, you have to get the machine going. That means you need to invest in entropy production.
For their experiment, the researchers built a simplified clock from a 50-nanometer thick, 1.5-millimeter long membrane stretched between tiny posts that vibrated with pulses of electricity. Counting every flex up and down as a tick, the team were able to show that more powerful electrical signals generated more regular and accurate ticks. This, however, came at the cost of adding more heat- or entropy- to the system.
"We don’t know for certain yet, but what we’ve found — for both our clock and for quantum clocks — is that there’s a proportional relationship between accuracy and entropy," says Ares. "It might not always be a linear relationship for other clocks, but it does look like the accuracy is bounded by the laws of thermodynamics."
The researchers say their findings may provide foundations for further exploration into how large scale laws of thermodynamics apply to nanosized devices. Their findings, they say, open the door towards an ‘Industrial Revolution at the nanoscale’.