  Liquids relax extremely slowly upon approaching the glass state. One
explanation is that an entropy crisis, due to the rarefaction of available
states, makes it increasingly arduous to reach equilibrium in that regime.
Validating this scenario is challenging, because experiments offer limited
resolution, while numerical studies lag more than eight orders of magnitude
behind experimentally-relevant timescales. In this work we not only close the
colossal gap between experiments and simulations but manage to create in-silico
configurations that have no experimental analog yet. Deploying a range of
computational tools, we obtain four estimates of their configurational entropy.
These measurements consistently confirm that the steep entropy decrease
observed in experiments is also found in simulations, even beyond the
experimental glass transition. Our numerical results thus extend the new
observational window into the physics of glasses and reinforce the relevance of
an entropy crisis for understanding their formation.
