Physicists Identify a Surprising Phenomenon of Aging in Materials Over Time
taylorvich writes:
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 Bohmer 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.
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