Consider three plausible technologies:

1. Artificial general intelligence
2. High-speed space travel
3. Self-reproducing spacecraft.
   If these are practical, they suggest that the universe could suddenly find itself completely saturated with advanced intelligence, even if it appears quite rarely.

For a wide range of possible final goals, it has been argued that rational agents are likely to deploy such technology and rapidly expand. And even if just a small fraction of intelligent life chooses to do so, the conclusion remains much the same.

Accessing a massive reserve of free energy should be a prime instrumental goal for almost any final goal that an ambitious rational agent could possess.

Intelligent life may be the universe’s large-scale, general-purpose tool for seeking out and minimizing deeply hidden reserves of free energy.

This would result in a tremendous amount of waste heat radiation, as ordinary matter is “burned” everywhere that life is active.

Depending on where the practical limits to technology reside, the universe could once again be filled with radiation, and thus pressure, inducing a backreaction on the scale factor.

the universe may be entering a kind of phase transition after all, complete with its own nucleation events, spherically expanding domains, and latent heat. But it’s not the result of hidden physics taking us by surprise. We are the transition.