Hi ljk

Personally I'd like to think intelligent life will do something about the long fade out - in the case of the Sun a mere 8% of its mass will be depleted of hydrogen when it goes off the Main Sequence. Why can't we help the core convect and cycle the whole of the Sun's mass through? At constant luminosity that'd extend its life over ~ 120 billion years. If we can then let the whole of its mass collapse to neutron star density - helped along by quark nuggets - that's liberate ~10^12 years of gravitational energy. Finally if we catalyse proton-decay then the Sun would be consumed in ~ 10^13 years at current luminosity. Alternatively collapsing it all the way to the Schwarzschild Radius would liberate 4.4 terayears of warmth.

Pretty much after ~ 10^13 years the regular stars would be gone and we'd have to start tapping dark matter. But Cirkovic's paper about ETIs moving to the Galactic Rim for heat dissipation kind of suggests the long-dark might be actively encouraged by ETIs pushing their thermodynamic limits and what They might use for power is debatable - the Galaxy's light is pretty thin that far out. Ultimately the Galaxy would be surrounded by a shell of heat dissipators trying to use & dump heat as close in temperature to the CMB as practical. Kind of like a technological version of the Holographic Principle.

Adam