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Physics

Heating and cooling seem to be fundamentally different, not opposites

Conventional thermodynamics says that heating and cooling are essentially mirror images of each other, but an experiment with a tiny silica sphere suggests otherwise

By Alex Wilkins

29 January 2024

Conventional thermodynamics explains why hot tea gets cold – but those laws don’t tell the full story

In Green/Shutterstock

Heating something up will always be quicker than cooling it down on a microscopic scale, according to a proposed new principle of thermodynamics. The two processes, long thought of as two sides of the same coin by physicists, seem actually to be fundamentally different.

While most people have an intuitive understanding of what temperature is, physicists have argued over a precise definition for centuries. A school textbook might say it is a measure of…

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