FTP, what is this phase exhibited by helium below a temperature of 2.18 Kelvins?
One phenomenological theory of their behavior was proposed by Tisza in 1940, and improved upon by Landau. They view the substance as composed of two components with varying relative density, leading to the so-called "second sound" effect. At low temperatures the excitations are phonons but at higher temperatures they are "rotons." The specific heat curve behaves as a logarithmic function near the transition temperature, which is called the lambda point. Substances in this phase are characterized by zero viscosity under certain conditions. FTP, what is this phase exhibited by helium below a temperature of 2.18 Kelvins?
One phenomenological theory of their behavior was proposed by Tisza in 1940, and improved upon by Landau.
superfluid (accept equivalents)