# Phase transition and energy conservation inside neutron star

I'm stuck at the moment with this simple question:

If a phase transition from hadronic to quark matter of 1st order with a big jump in the energy density occurs inside a neutron star one can get unstable star configurations by integrating the TOV equation which means the graviational pressure dominates the pressure inside the star thus the star collapses.

But where does the energy of this sudden energy jump come from?

It seems confusing to me at the moment that energy coming from gravitational energy leads to new state of matter with higher energy density (this makes sense, because of the increasing pressure) but that again leads to a bigger "mass/energy" of the system causing it to collapse? Wouldn't that be a violation of energy conservation?

The energy was in the system anyway before actually CAUSING gravitation. Where is my error in reasoning?

Thank you.

• I don't understand - any phase transition will be to a state with lower total energy density. Also, what do you mean by "gravitational pressure"? – Rob Jeffries Jun 22 '18 at 18:13