Characteristic length of the glass transition

Three lengths for the dynamic glass transition will be compared: a kinemati c length from computer simulation, a heterogeneity length from multidimensi onal nuclear magnetic resonance, and a characteristic length from calorimet ry. A qualitatively consistent picture is obtained after discussion of thei r different origins. The difficulties with respect to measured and simulate d lengths ate exposed. Heat capacity spectroscopy data for temperatures and frequencies near and above the crossover region of the dynamic glass trans ition are reported for two substances: poIy(n-decyl methacrylate), PnDMA, a nd 6-(4-benzyl oxy phenyl)-1, 2, 3, 4 tetraphenyl fulvene, TPCP-BO.