Lots of black holes, blocked from interacting in any way because spacetime expands too fast and too far, excruciatingly slowly losing mass one tiny particle at a time until (10^100)^100 years later they all fizz out, leaving solitary photons just cruising along on their own, never to meet any other photon again.
At this point, mass, velocity, distance, volume etc all lose meaning.
smaaskakk_tronder t1_iui7blz wrote
Reply to When the last star dies by trunktunk
Lots of black holes, blocked from interacting in any way because spacetime expands too fast and too far, excruciatingly slowly losing mass one tiny particle at a time until (10^100)^100 years later they all fizz out, leaving solitary photons just cruising along on their own, never to meet any other photon again. At this point, mass, velocity, distance, volume etc all lose meaning.