The Mysteries of Glass: Is It a Solid or a Liquid?

University courses Physical Sciences
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Glass is one of the most fascinating materials in the world, blending science, art, and mystery. Unlike most solids, glass doesn’t have a crystalline structure. Instead, it’s amorphous, meaning its atoms are arranged randomly, much like a liquid. This unique state has sparked debates: is glass truly a solid or just a supercooled liquid?

Chemically, glass is often made by melting silica (SiO₂) with other compounds to lower its melting point. This molten mixture is rapidly cooled to prevent crystallization, resulting in a rigid yet disorderly structure. Its optical clarity and malleability make it indispensable in fields ranging from architecture to technology.

In chemistry, studying glass can reveal insights into its mechanical and thermal properties. Researchers are constantly innovating, developing specialty glasses like Gorilla Glass for smartphones or bioactive glasses used in medical implants. For students, the chemistry of glassmaking is an opportunity to explore materials science in a hands-on way, blending theoretical knowledge with practical application.

Whether you’re examining its atomic structure or crafting your own creations, the study of glass offers a unique perspective on how chemistry shapes the world around us. It’s a journey that bridges science and creativity, perfect for the curious chemist.

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Fascinating topic!

There is a great edition of Melvin Bragg’s In Our Time on Radio 4 that’s worth a listen:

The Science of Glass

In Our Time

While glass items have been made for at least 5,000 years, scientists are yet to explain, conclusively, what happens when the substance it’s made from moves from a molten state to its hard, transparent phase. It is said to be one of the great unsolved problems in physics. While apparently solid, the glass retains certain properties of a liquid. At times, ways of making glass have been highly confidential; in Venice in the Middle Ages, disclosure of manufacturing techniques was a capital offence. Despite the complexity and mystery of the science of glass, glass technology has continued to advance from sheet glass to crystal glass, optical glass and prisms, to float glasses, chemical glassware, fibre optics and metal glasses.

With:

Dame Athene Donald
Professor of Experimental Physics at the University of Cambridge and Master of Churchill College, Cambridge

Jim Bennett
Former Director of the Museum of the History of Science at the University of Oxford and Keeper Emeritus at the Science Museum

Paul McMillan
Professor of Chemistry at University College London

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