For half a century, the unique way glass transmits sound waves and vibrations at low temperatures has left scientists puzzled, distinguishing it from other solids. The riddle has been unraveled by two physicists, who have revisited and revised an old theory once discarded, offering an accurate explanation of glass’s distinct behavior.
University of Konstanz researchers shed light on the physics of how glass diminishes sound: A physics enigma unraveled through the resurrection of a neglected theory.
The knowledge needed to understand this phenomenon has been present but neglected for around fifty years. The physics community has been mystified by the way glass handles vibrations at lower temperatures.
Why does glass handle sound waves differently than other solid materials, vibrating in a unique manner?
To understand and correctly calculate sound’s propagation in glass, two physicists from Konstanz, Matthias Fuchs and Florian Vogel, took a 20-year-old model previously dismissed by experts and reworked it. They’ve published their new perspective on this old model in the journal Physical Review Letters.
Table of Contents
Damped Vibrations
When sound waves are sent through glass and observed closely, a noticeable damping of the vibrations occurs, something that isn’t found in other solids. This has profound implications for the thermal characteristics of glass, including heat transfer and heat capacity. Although this effect is recognized in physics, no theoretical model existed that could correctly depict it or guide more complex calculations of sound transmission in glass.
Glass, unlike crystalline solids, is a disordered solid. Its particles are randomly placed, not aligned like the precisely ordered building blocks in most solids. When vibrations are excited in crystalline solids at low temperatures, they pass uniformly without loss, similar to a wave in a stadium. In glass, the particles’ random positions cause the uniform wave to break into several smaller waves, leading to a damping effect known as “Rayleigh damping.”
Revisiting a Previously Rejected Model
Roughly two decades ago, a model called the “Euclidean random matrix approach” (ERM) was proposed by physicists Marc Mezard, Giorgio Parisi (Nobel Prize in Physics 2021), Anthony Zee, and others to describe the anomalies in glass. Despite its simplicity, the model had inconsistencies and was rejected by the scientific community.
Professors Matthias Fuchs and Florian Vogel revived this old model, addressing the unanswered questions and analyzing it using Feynman diagrams, which revealed the patterns of scattered waves.
The investigation led by Fuchs and Vogel resulted in realistic calculations of sound propagation and the damping effect in glass. According to Fuchs, the original authors were right in their model; disordered arrangements of harmonic oscillations explain glass’s anomalies at low temperatures.
But the story doesn’t end with the rediscovery of this model. For Fuchs and his team, it’s a beginning: the right model to use for further studies, particularly in the realm of quantum mechanical effects. A promising path for future research has been opened.
Reference: “Vibrational Phenomena in Glasses at Low Temperatures Captured by Field Theory of Disordered Harmonic Oscillators” by Florian Vogel and Matthias Fuchs, 7 June 2023, Physical Review Letters.
DOI: 10.1103/PhysRevLett.130.236101
Funding for the research was provided by the German Research Foundation (DFG) as part of the Collaborative Research Centre SFB 1432 “Fluctuations and Nonlinearities in Classical and Quantum Matter beyond Equilibrium.”
Frequently Asked Questions (FAQs) about glass sound conduction
What was the mystery about how glass conducts sound?
For about 50 years, scientists were perplexed by how glass conducts sound waves and vibrations differently than other solids at low temperatures. Unlike crystalline solids, where particles are regularly arranged, glass’s particles have random positions, leading to a unique damping effect called “Rayleigh damping.” This phenomenon had not been accurately explained until recently.
Who solved the mystery of sound conduction in glass, and how?
Matthias Fuchs and Florian Vogel, physicists at the University of Konstanz, solved the mystery by revisiting and reworking a 20-year-old model known as the “Euclidean random matrix approach” (ERM) that had been discarded by experts. They published their findings in the journal Physical Review Letters.
What is the significance of the damping of vibrations in glass?
The damping of vibrations in glass has far-reaching consequences for its thermal properties, such as heat transfer and heat capacities. Understanding this phenomenon also enables more complex calculations of sound propagation in glass, which can have various practical applications.
Why was the old model discarded, and how was it revised?
The original model, known as the “Euclidean random matrix approach” (ERM), was discarded about 20 years ago due to some inconsistencies. Matthias Fuchs and Florian Vogel revisited the old model, found solutions to the open questions that had led to its rejection, and examined it using Feynman diagrams to provide accurate calculations of sound propagation in glass.
What are the future prospects of this rediscovered model?
The rediscovered and revised model is considered a starting point for further studies, especially related to quantum mechanical effects. The right model has been found for more complex calculations, paving the way for potential advancements in the understanding of disordered harmonic oscillators, offering promising paths for future research.
5 comments
what’s the practical application of this, Does it affect our daily lives or just a scientific curiosity. anyway, its still cool that they solved an old mystery.
does this mean we’ll have better glass in our windows or something. Not sure I get the big deal but sounds impressive.
Great read! The part about them rediscovering a discarded theory is just amazing, it’s like finding a lost treasure, science is full of surprises.
Wow, this is a big breakthrough in physics! I never thought glass could be so different from other solids. Wish I could understand all the details though.
I remember studying Rayleigh damping in college, but i didn’t realize it had a connection to glass, This piece makes me want to dive back into physics again, fascinating stuff!