Comment on "Direct evidence for strong crossover of collective excitations and fast sound in the supercritical state"

TL;DR

This paper critically examines and refutes three claims made by Fomin et al. regarding generalized hydrodynamics and sound dispersion in supercritical fluids.

Contribution

It provides a detailed critique clarifying misconceptions about collective excitations and sound behavior in supercritical states.

Findings

Identifies errors in Fomin et al.'s claims

Clarifies the correct interpretation of sound dispersion

Highlights the importance of proper hydrodynamic methodology

Abstract

We comment on three incorrect claims in the paper by Fomin et al (arXiv:1507.06094) concerning the generalized hydrodynamic methodology and positive sound dispersion in fluids.