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posted by janrinok on Monday January 29, @11:45PM   Printer-friendly

https://phys.org/news/2024-01-physicists-phenomenon-aging-materials.html

Physicists in Darmstadt are investigating aging processes in materials. For the first time, they have measured the ticking of an internal clock in glass. When evaluating the data, they discovered a surprising phenomenon.

We experience time as having only one direction. Who has ever seen a cup smash on the floor, only to then spontaneously reassemble itself? To physicists, this is not immediately self-evident because the formulae that describe movements apply irrespective of the direction of time.

A video of a pendulum swinging unimpeded, for instance, would look just the same if it ran backwards. The everyday irreversibility we experience only comes into play through a further law of nature, the second law of thermodynamics. This states that the disorder in a system grows constantly. If the smashed cup were to reassemble itself, however, the disorder would decrease.

You might think that the aging of materials is just as irreversible as the shattering of a glass. However, when researching the movements of molecules in glass or plastic, physicists from Darmstadt have now discovered that these movements are time-reversible if they are viewed from a certain perspective.

The team led by Till Böhmer at the Institute for Condensed Matter Physics at the Technical University of Darmstadt has published its results in Nature Physics.

Glasses or plastics consist of a tangle of molecules. The particles are in constant motion, causing them to slip into new positions again and again. They are permanently seeking a more favorable energetic state, which changes the material properties over time—the glass ages.

In useful materials such as window glass, however, this can take billions of years. The aging process can be described by what is known as the "material time." Imagine it like this: the material has an internal clock that ticks differently to the clock on the lab wall. The material time ticks at a different speed depending on how quickly the molecules within the material reorganize.

Since the concept was discovered some 50 years ago, though, no one has succeeded in measuring material time. Now, the researchers in Darmstadt led by Prof. Thomas Blochowicz have done it for the first time.

"It was a huge experimental challenge," says Böhmer. The minuscule fluctuations in the molecules had to be documented using an ultra-sensitive video camera. "You can't just watch the molecules jiggle around," adds Blochowicz.

Yet the researchers did notice something. They directed a laser at the sample made of glass. The molecules within it scatter the light. The scattered beams overlap and form a chaotic pattern of light and dark spots on the camera's sensor. Statistical methods can be used to calculate how the fluctuations vary over time—in other words, how fast the material's internal clock ticks. "This requires extremely precise measurements which were only possible using state-of-the-art video cameras," says Blochowicz.

But it was worth it. The statistical analysis of the molecular fluctuations, which researchers from Roskilde University in Denmark helped with, revealed some surprising results. In terms of material time, the fluctuations of the molecules are time-reversible. This means that they do not change if the material time is allowed to tick backwards, similar to the video of the pendulum, which looks the same when played forwards and backwards.

More information: Böhmer, T. et al, Time reversibility during the ageing of materials. Nature Physics (2024). DOI: 10.1038/s41567-023-02366-z


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  • (Score: 1) by jahaven on Tuesday January 30, @12:59AM

    by jahaven (12434) on Tuesday January 30, @12:59AM (#1342339)

    are physicists near to find out that time has a log ?

  • (Score: 3, Informative) by Gaaark on Tuesday January 30, @02:51AM (2 children)

    by Gaaark (41) on Tuesday January 30, @02:51AM (#1342343) Journal

    The article makes less sense than this:

    Costello: Now I throw the ball to first base, whoever it is drops the ball, so the guy runs to second. Who picks up the ball and throws it to What. What throws it to I Don't Know. I Don't Know throws it back to Tomorrow—a triple play.
    Abbott: Yeah, it could be.
    Costello: Another guy gets up and it's a long fly ball to Because. Why? I don't know. He's on third and I don't give a darn!
    Abbott: What was that?
    Costello: I said, I DON'T GIVE A DARN!
    Abbott: Oh, that's our shortstop!

    Can anyone explain WTF the article is about?

    --
    --- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
    • (Score: 2, Insightful) by shrewdsheep on Tuesday January 30, @08:51AM

      by shrewdsheep (5215) on Tuesday January 30, @08:51AM (#1342373)

      If you look very hard at glass, you can tell its age. Or not (aging seems reversible, but only at tiny time scales). TLDR.

    • (Score: 0) by Anonymous Coward on Wednesday January 31, @09:48AM

      by Anonymous Coward on Wednesday January 31, @09:48AM (#1342483)
      My interpretation is they did the equivalent of seeing a rubber block wobble and claimed that means time can "tick backwards" in the material.
  • (Score: 2) by Rosco P. Coltrane on Tuesday January 30, @03:20AM

    by Rosco P. Coltrane (4757) on Tuesday January 30, @03:20AM (#1342344)

    is a phenomenon that is known and exploited. For instance, maraging steel [wikipedia.org] and aging aluminum [thermalprocessing.com].

  • (Score: 3, Interesting) by bzipitidoo on Tuesday January 30, @04:15AM (1 child)

    by bzipitidoo (4388) on Tuesday January 30, @04:15AM (#1342348) Journal

    "Aging" does not seem a good term for this. "Settling" would be better. Biological aging rather swiftly renders an organism less and less fit, weakening and slowing it. This is not necessarily true of materials, even those of biological origin such as wine. Certainly, fitness has no inherent meaning for a material, it only has meaning in the context of whatever purpose life might have for it. If I was the editor, I would've sent this article back for a rewrite.

    • (Score: 3, Funny) by Rosco P. Coltrane on Tuesday January 30, @04:39AM

      by Rosco P. Coltrane (4757) on Tuesday January 30, @04:39AM (#1342353)

      Many humans age like wine bottles: they move as little as possible, smell musty on the outside and slowly increase their alcohol content.

  • (Score: 2, Funny) by Anonymous Coward on Tuesday January 30, @04:54AM

    by Anonymous Coward on Tuesday January 30, @04:54AM (#1342355)

    In the event of imminent time reversal, break glass.

  • (Score: 0) by Anonymous Coward on Tuesday January 30, @05:34PM

    by Anonymous Coward on Tuesday January 30, @05:34PM (#1342420)

    A video of a pendulum swinging unimpeded, for instance, would look just the same if it ran backwards.

    I suspect that by "unimpeded" they mean an ideal pendulum, consisting of a massless cord with a point weight at its end, attached to a frictionless point and swinging in a perfect vacuum. Try making a video of that!

    Meanwhile, a video of a real pendulum running backwards, would start with the pendulum at rest, then starting to make increasingly wider arcs. When it reaches its highest point, a hand will appear, grabbing the weight at the end of the string and moving it to the rest point. I'm pretty sure that this is quite different from a video of a pendulum running normally.

  • (Score: 2) by acid andy on Tuesday January 30, @10:56PM

    by acid andy (1683) on Tuesday January 30, @10:56PM (#1342454) Homepage Journal

    We experience time as having only one direction. Who has ever seen a cup smash on the floor, only to then spontaneously reassemble itself? To physicists, this is not immediately self-evident because the formulae that describe movements apply irrespective of the direction of time.

    Who has ever seen two cups smash on the floor into exactly the same configuration and orientation of pieces either? When we look for a spontaneously assembling cup, we're waiting to observe a one of a very small set of configurations of particles. The set of configurations we would be happy to call a smashed cup is very much larger. So it's not a fair comparison.

    --
    If a cat has kittens, does a rat have rittens, a bat bittens and a mat mittens?
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