Various techniques give values for the ratio of the speed of sound cs squared to the square of the speed of light as it varies with isospin chemical potential. NLO χPT: next-to-leading order chiral perturbation theory; pQCD: perturbative quantum chromodynamics; LQCD: lattice quantum chromodynamics; GP: Gaussian process combination. Note the LQCD result peaks at √(3/4). Credit: Physical Review Letters (2025). DOI: 10.1103/PhysRevLett.134.011903 Neutron stars are some of the densest objects in the...