We are surrounded by so many commonplace glass objects, they are almost transparent to our notice: car windows, casserole dishes, food jars, soda bottles, even buildings! It is a great feat of science and technology that glass has become so affordable to produce and so strong that it can be used for such a variety of purposes. However, there are also craftspeople who value glass for slightly different reasons: because it can be colored, heated and stretched into creative shapes for entirely aesthetic purposes. If you would like to be surprised by some breathtaking and smile-inducing uses for glass, take a visit to the Chihuly exhibit at Boston’s Museum of Fine Arts. Dale Chihuly and the studio he founded have been creating pieces of blown glass for over 40 years . The results range from decorative vases, to exquisite flowers, to crazy shapes that would fit right in with Alice in Wonderland (Figure 1). The exhibit, entitled “Through the Looking Glass”, is both amusing and amazing.
The experience of walking through the exhibit feels like a process of discovery: each room houses a different style of blown glass objects with a different mood and feel. A soundtrack of “wows” and “whoas” plays softly and repeatedly from the viewers’ lips. Under the “Persian Ceiling” a dozen or more people pause to bask in the colorful light, gazing at the ceiling above, and smile continuously as they tell each other “I like… I like… I like…”
Figure 1. A selection of the glasswork from “Through the Looking Glass”.
Some passersby say they feel like they are in the ocean when they walk through the gallery, and it is easy to agree. Light plays off the glass in a similar way it interacts with the surface of water, scattering and diffracting around the room. Many of the vases and bowls look like they might still be flowing materials, with all their curves and contours. Other pieces look like reeds that are flexing in an undersea garden. This appearance of stretch and motion is in stark contrast to the brittle reality of the finished artwork! It hints at their process of creation, however, because the pieces indeed began as a malleable and flowing material. Like a three-dimensional snapshot in time, the pieces of artwork become representations of the final moment in the glass-working process.
By watching videos of the Chihuly Studio members at work, we can also get a four-dimensional glimpse of the process — and this is possibly even more amazing than the final product . Teams of creative people coax blobs of hot and elastic glass along inventive trajectories, and then encourage those moving pieces to hold their shape as they cool and become rigid. Many of the unique features of the artwork are due to Chihuly’s own creativity, personality, and style. Additionally, his method of working with teams of glassblowers allows him to create artwork of larger scale and intricacy than a single artist might create.
However, there are also aesthetic features of blown glass that are due to the nature of the material itself. One reason that glass is fascinating to both artists and scientists is because of the way that it behaves when it is heated near its melting point, stretched, and then cooled. Although many substances form an organized, crystal structure when they are cooled below their melting point (imagine the crystals of ice inside a freezer), the molecules in glass remain disorganized as they cool  (Figure 2).
Figure 2. Comparison of the molecular structure of glass and other typical solids.
What does this mean to a glassblower? It means that there is a temperature range where glass can sort of flow like a liquid, but also have some strength like a solid. This is what allows the glass to be heated until it is stretchy, but not yet a puddle of liquid. Then it can be pulled into arrangements, often supported by metal rods and tools, that hold their shape as they cool.
What does this mean to scientists? This is actually still a puzzle to chemists who are interested in the phase transition of glass — from liquid to solid or vice versa — because it is not known exactly how the different types of molecules in glass behave to create the observed behavior . One way to visualize the puzzle is to think about a bucket of sand. It is kind of like a solid, because you can stand on the sand and it will resist the force of your weight. But it is also kind of like a liquid, because if you tip the bucket it will flow out in response to the force of gravity. Similarly, glass manages to respond to certain types of forces in a way that looks like a solid, but responds to other types of forces in a way that looks like a liquid. Although we can observe this over and over on the macroscopic scale, it is not yet clear how the different molecules in glass behave during the phase transition.
Although not everyone is necessarily curious about the behavior of molecules in glass, it is fun to see how both scientists and artists can enjoy the nature of this inorganic substance: glass is useful because of the way it moves and stretches when heated, and the way it holds that same shape as it cools into a solid. Industries have taken advantage of this to make sheets of glass for our windows. Artists and craftspeople have taken advantage of this to create beautiful and provocative arrangements of colored objects, which are viewed and enjoyed by spectators like us!
Chihuly: Through the Looking Glass is on exhibit at the Museum of Fine Arts in Boston, MA until August 7th, 2011.
Shannon McArdel is a PhD student in the Immunology program at Harvard Medical School.
 Dale Chihuly’s website: http://www.chihuly.com
 To view videos of Dale Chihuly and his teams in action: http://www.chihuly.com/projects
 Ediger, M.D. (2000) Movies of the glass transition. Science 287 no.5453, pp604-605.
 Weitz, D.A. (2009) Unjamming a polymer glass. Science 323:214-215.