Friday, June 18

The precision of a watch depends on the entropy

The precision of a watch depends on the entropy

The precision of a watch depends on the entropy

New research has found that the accuracy of atomic clocks, closely related to entropy, also occurs in classic clocks.

Every organized system tends to disorder or entropy: that means that, as time passes, any system becomes more disorderly or chaotic.

The entropy it is assimilated with the arrow of time and marks the irreversibility of physical processes: we can break an egg and beat it, but that disorder that we have created cannot be put back together and put the egg inside its shell after beating.

This limitation has led us throughout history to develop technologies to catch time, first with hourglasses, then with water clocks and even sundials.

More modernly, we have created mechanical clocks, quartz clocks (90% of the current ones) and even atomic ones, based on the measurement of a resonance of the atoms to establish the highest precision that we have achieved in the measurement of the passage of time.

Can we measure time?

But the entropy associated with the passage of time raises an interesting question: If clocks are subject to entropy, to what extent can we trust how they measure time?

New research, led by Anna Pearson, from Cambridge Quantum Computing · QNLP, has found that the precision of all clocks is related to the entropy they generate, which means that there is a link between the passage of time and its measurement.

In an article published in the journal Physical Review X, the authors of this research point out that all clocks, in one way or another, use the evolution of nature towards higher entropy states to quantify the passage of time.

They add that due to the statistical nature of the second law of thermodynamics and the corresponding flows of entropy, these fluctuations are involved in the performance of any watch.

This suggests a profound relationship between increased entropy and the quality of the ticking of the clock, they categorically state.

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Entropy and precision

Entropy and precision And they go even further: taking atomic clocks as a reference, in which each bit of entropy increases their precision linearly, they discovered that classical clocks also increase their precision as the entropy generated by the measurement of time increases.

They theoretically showed that the maximum possible precision for a classical clock is proportional to the entropy created by each tick, similar to the known limit for a quantum clock.

In their research they measured both precision and entropy using a relatively simple experiment. They used a very thin membrane and only 1.5 millimeters to which they hung from two poles.

The membrane worked like a clock: its task was to measure the passage of time. An electrical signal sent at regular time intervals, similar to the ticking of a clock, moved the membrane up and down.

Precision and heat

Precision and heat An antenna registered that movement and determined something curious: the stronger the electrical signal, the greater the precision that this original watch marked. In addition, the higher the precision, the higher the entropy, derived from the heat produced in the circuit, which allows the passage of time to be measured.

The researchers consider that the same thing that happens when we measure time on a quantum scale, also happens when we try to trap time with classical physical systems: entropy is decisive for precision.

In any case, it cannot be generalized: the clock used in the experiment is not equivalent to any possible clock that measures time, so we must be cautious about establishing that time is always measured with the same precision in the quantum world. and in the classical, depending on the entropy generated by the measurement.


Reference Measuring the thermodynamic cost of timekeeping. A. N. Pearson et al. Phys. Rev. X (Accepted Paper).

Top image: Joshua Choate on Pixabay

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