Many thanks to the authors for their comments about my Reference Frame column. I have just a few remarks in reply.
Ian Hodge and I agree that we still need a deep, first-principles understanding of the remarkably successful Adam–Gibbs formula, in both its original and extended nonlinear versions. It will be interesting to see whether the physical mechanisms underlying the two related phenomenologies are actually the same in their respective regions of validity.
Jeppe Dyre remarks that some basic features of the glass transition are captured by the simple asymmetric double-well model. He clearly understands that there is a great deal more to the mystery than that, and I think he is making his point in an interesting way. Viscous relaxation rates near the glass transition are about 15 orders of magnitude slower than molecular vibration frequencies. As Dyre points out, processes on both time scales are taking place in glass-forming systems. How do we relate one to the other?
I admit I’m puzzled by the other two letters. True, all molecular interactions are ultimately quantum mechanical in nature; but, like most specialists in this field, I see no reason to think that the generic glass transition is intrinsically a quantum, as opposed to classical, phenomenon. Hans-Jürgen Hoffmann seems to imply otherwise. In reply to Brahama Sharma, perhaps it will be helpful to say that when I talk about the “glass transition,” I am thinking of metallic glasses, polymeric glasses, and a wide variety of other noncrystalline materials, not just silicate glass.
