Low- and high-temperature anomalies in the physical properties of solid methane

Near 20.48K and in the temperature range 60--70K, anomalous behavior of thermodynamic, spectral, plastic, elastic and other properties of solid methane is observed. The anomalies in the vicinity of 20.48K are due to the phase $\alpha-\beta$ transition. Anomalies in a relatively wide range of 60--70K are shown to be related to the essentially quantum nature of the collective rotation of methane molecules. The provided analysis of the high-temperature anomalies encompasses a more extensive set of phenomena in comparison with the low-temperature ones. Key words: solid methane, anomalies of physical properties, phase transition, rotational temperature, quantum-classical transition.