oopsemist

Opposite is true also: it's possible to add energy into three body system and increase distance between them (antigraviation). In principle, spherical gradient of gravitation creates possibility to increase orbit using only energy and interaction between masses even in two body system (if smaller body can change it shape and distibution of mass to simulate three body system). I had idea of such aparatus when I was student 30 years ago, but then I forgot the details.

> It's particularly interesting because conservation of energy does not hold on such large scales.

IMHO, conservation of energy still applies, so Big Bang model is just wrong. Use Occam's razor when in doubt.

Yes, it should increase on paper, but no source of energy to power that expansion is found yet. Big Shrink can power itself, so I'm voting in favor of https://en.wikipedia.org/wiki/Shapley_Attractor