The equation of state for neutron matter

The equation of state for cold neutron matter has been derived for densities of 10¹²–10¹⁶ g/cm³. The energy density, the pressure and the velocity of sound have been calculated from nuclear forces by quantum mechanical many body techniques, which are well established in nuclear physics. It is found, that neutron matter is not bound and becomes superluminal and ultrabaric at densities of about 10¹⁵ g/cm³. In order to justify these strange results it is shown that the same physical assumptions which lead to the superluminal and ultrabaric behaviour in our calculation yield the same effects also in the lorentz invariant classical models of Zeldovich, Bludman and Ruderman.