Ancient glass windowpanes are warped, fragile things that tend to be thicker at the bottom and thinner at the top. And we all recall the mind-blowing moment that we were told that that sort of aging is because glass is not solid at all, but a very slow-moving liquid. The theory goes: "The glass is flowing downward as it ages." As it turns out, we were duped.
But don't feel bad. Most of the scientific community was fooled as well. It took an open-minded professor and a doctoral candidate's unique qualifying exam results to call the widely accepted theory into question. When Texas Tech's doctoral candidate Jing Zhao turned in her results, Professor Gregory McKenna was very intrigued.
And thus phase two of their experiment began. Joining forces with Professor Sindee Simon, Zhao next selected a much older, much more stable piece of glass to examine. What she chose was a 20 million-year-old piece of amber from the Dominican Republic. Again, their results showed a lack of what is termed "divergent relaxation times." After 20 million years of aging, the amber presented no signs of flowing.
This flies in the face of everything we think we know about the nature of glass. But Professor McKenna et al. aren't finished yet. They've collected a whole new batch of ancient bits of glass materials, one of which, is a piece of amber 220 years old. If the issue with a 20 million year old fragment of amber not showing signs of liquidy age was that it was too young, surely another artifact 200 million years its senior will tell us something different. If it doesn't, however, we may all have to change the way we think of one of the world's most widely used materials.