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posted by mrpg on Tuesday July 29 2025, @12:15PM   Printer-friendly
from the Just-take-it-to-HIP-67522-b dept.

Arthur T Knackerbracket has processed the following story:

Wafer-thin sheets of gold shot briefly with lasers can be heated up to 14 times their melting point while remaining solid, far beyond the theoretical limit, raising the possibility that some solids may have no upper melting point at all.

Superheating is a common phenomenon where a solid can heat up beyond its melting point, or a liquid can heat up past its boiling point, without changing state. For example, a cup of water heated in a microwave can reach temperatures above 100°C (212°F), as long as the cup is sufficiently smooth and still. However, as soon as the cup is jostled, the water will violently boil.

For solids, many physicists have proposed an upper limit for superheating, at a temperature around three times the standard melting point in kelvin. This point is called the entropy catastrophe, which is where the entropy, often defined as the amount of disorder in a system, for the solid state would become larger than if the substance were liquid. If the substance remained solid above this temperature, then it would violate the second law of thermodynamics, which says that entropy cannot decrease over time for most systems.

[...] It would also be interesting to see whether this applies to other solids apart from gold, says Vinko, and whether there is any upper limit to heating before melting. “The thing that’s intriguing here is to ask the question of whether or not it’s possible to beat virtually all of thermodynamics, just by being quick enough so that thermodynamics doesn’t really apply in the sense that you might think about it.”

Journal Reference: White, T.G., Griffin, T.D., Haden, D. et al. Superheating gold beyond the predicted entropy catastrophe threshold. Nature 643, 950–954 (2025). https://doi.org/10.1038/s41586-025-09253-y

DOI: 10.1038/s41586-025-09253-y


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  • (Score: 5, Informative) by c0lo on Tuesday July 29 2025, @03:27PM

    by c0lo (156) Subscriber Badge on Tuesday July 29 2025, @03:27PM (#1411907) Journal

    Thermodynamics and statistical mechanics are based on ergodic hypothesis [wikipedia.org]
    At duration of 45 femtosecs (the laser pulse's duration), we're a bit outside the bounds of ergodicity to speak about entropy's direction - thermodynamics and statistical mechanics aren't suited anymore to offer predictions.

    --
    https://www.youtube.com/@ProfSteveKeen https://soylentnews.org/~MichaelDavidCrawford
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