Black box particles

So, I was thinking: if I could create a universe, with whatever physical laws I wanted, how would I do it? My design goal would be to create a universe which could sustain sapient life indefinitely. Even if we avoid all the little hazards along the way, life in our universe won't be able to last more than a few trillion years, if our physics are correct. So, how could this problem be solved?

My idea was to create what I call "black box particles." There don't need to be many - a few trillion would suffice. They would be subject to the gravitational force, but not to decay and they would not react with antimatter.

Black box particles could exist in many states, but there are four that I think are important:

Energy emitting particles would emit photons in huge quantities, and never run out. Energy absorbing particles would attract and gobble up photons.

Magnetic particles could be moved about by the electromagnetic force. This is important because it would allow an advanced civilization to harness their power.

Black box particles would change state at random. This shouldn't happen too frequently; a single particle could remain in one state for several billion years. Additionally, particles could randomly disappear and reappear somewhere else, in greater concentrations of matter. This would prevent the black box particles from getting lost in deep space somewhere.