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Resurrected theory solved: 50 year old physics puzzle buried


How glass muffles sound: Konstanz Faculty researchers remedy a physics thriller by rediscovering a discarded thought.

Typically the knowledge is already there, simply flawed. For almost fifty years, the peculiar vibrational habits of glass at low temperatures have puzzled physicists. Glass conducts sound waves and vibrations fully in another way than strong supplies: it vibrates in another way. Nonetheless, why?

And the way can one precisely calculate the propagation of sound in glass? Two physicists from Konstanz, Mathias Fuchs and Florian Vogel, have now discovered the reply: they’ve taken an outdated mannequin, constructed some 20 years in the past and rejected by specialists on the time, and rebuilt it Was. His new perspective on the outdated pondering has now come to the fore in Physics Analysis Letters.

damp vibration

For individuals who ship sound waves by way of glass and measure them fairly precisely, you may see some damping of vibrations that’s absent in numerous strong supplies. This has far-reaching penalties on the thermal properties of the glass, akin to warmth switch and warmth capability. The impact is well-known in physics, however till now there was no theoretical mannequin that might correctly describe it and supply a framework for extra advanced calculations of sound propagation in glass.

The glasses are strong. Not like crystalline solids, the particles that make up a glass don’t have to be repeatedly organized. In most solids, the particles line up virtually completely, forming blocks organized like in an actual lattice. When wave vibrations are generated in such crystalline solids at low temperatures, the particles cross the vibration within the course of their undivided neighbors. The vibration travels in a uniform wave with out loss, very like La-wave in a stadium.

stained glass

In distinction, the glass particles shouldn’t be organized in a regular lattice, however relatively have random positions with out strict order. The incoming oscillatory waves mustn’t proceed in a uniform sample. As a substitute, the vibrations happen at random positions of the particles and are moved in corresponding random patterns. The result’s that the uniform wave breaks up and splits into many smaller waves. This impact causes diffuse moisture. Physicist Lord Rayleigh used this mechanism of scattering of daylight by irregularities within the environment to elucidate the blue shade of the sky, which is why the impact is known as Rayleigh damping.

Rediscovering a Discarded Mannequin

About 20 years in the past, physicists Marc Mezard, Giorgio Parisi (2021 Nobel Prize in Physics), Anthony Zee and their colleagues described these glass anomalies utilizing a mannequin of oscillations at random positions referred to as the Euclidean random matrix (ERM). did. expertise. . A easy mannequin that was mainly the reply, says Matthias Fuchs, professor of Maudlin Condensed Matter Principle on the College of Konstanz. Nevertheless, the mannequin nonetheless had some inconsistencies and was due to this fact rejected by specialists. and fell into oblivion.

Mathias Fuchs and his colleague Florian Vogel as soon as once more adopted the outdated mannequin. They discovered options to open questions that the science group couldn’t reply on the time, and examined the revised mannequin by taking a look at its Feynman diagrams. These helpful graphs had been launched by Richard Feynman within the idea of quantum self-discipline and revealed regularities throughout the scattered wave patterns.

The outcomes of Mathias Fuchs and Florian Vogel offered correct calculations of sound propagation and damping results inside glass. Fuchs explains, Méjard, Parisi and Zee have been appropriate of their sensible mannequin: harmonic oscillations in a disordered coupling create clear glass anomalies at low temperatures.

Nonetheless, the rediscovered dummy is much from the very best a part of the story: for us, it’s the beginning line: we’ve now discovered the very best dummy that we are going to now use for additional calculations, particularly quantum mechanical outcomes. For, Mathias. Fuchs says.


The thriller of glass and its attribute vibrational habits at low temperatures have lengthy intrigued scientists. Nonetheless, researchers on the Konstanz Faculty have made a breakthrough by rediscovering and modifying an outdated and discarded mannequin. They discovered that the cup dampens sound waves and vibrations differently from totally different solids as a result of disordered mixing of its particles. This damping impact, referred to as Rayleigh damping, happens when a uniform wave of vibration is unfold out into smaller waves. By reshaping the outdated mannequin and observing it by way of Feynman diagrams, scientists have been capable of precisely calculate sound propagation in glass and clarify its anomalies at low temperatures. This discovery is barely the start, as researchers can now uncover extra calculations, primarily associated to quantum mechanical leads to the glass.

often requested questions

What are the everyday vibrational habits of glass at low temperatures?

Glass conducts sound waves and vibrations in another way than fully totally different strong supplies. It additionally seems to have some vibration damping that’s absent within the numerous provides.

Why was it troublesome to calculate the propagation of sound in glass at low temperatures?

Glass is a disordered robust materials with irregularly organized particles, in distinction to crystalline solids with repeatedly organized particles. The random affiliation of the glass particles causes the dispersing of the approaching oscillatory wave into smaller waves, which lie contained in the damping impression. Till now, there was no theoretical mannequin that precisely described this phenomenon and allowed good calculations.

What’s Rayleigh Damping?

Rayleigh damping is the phenomenon by which a uniform wave of vibration is damaged up and unfold into many smaller waves because of random mixing of particles. The notion is called after the physicist Lord Rayleigh, who used a similar mechanism to elucidate the blue shade of the sky.

What’s the significance of the rediscovered mannequin?

The rediscovered phantom, which was initially discarded, offers affordable calculations of sound propagation and damping impression on the glass. This serves as a beginning place for additional analysis, which considerably explores the results of quantum mechanics in glasses.


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