I think there is a flaw in your reasoning, accepting that you are bringing
Western concepts of physics to bear on this issue.
If a citta-kkhana travelled at the speed of light from Pluto to Earth no
time would pass at all as far as it was concerned according to Einstein's
theories which showed time to be relative. Time would pass normally for an
observer on Pluto, or Earth, of course, but not from the citta-kkhana point
of view. At lower speeds, of course, time would dilate to a differing
extent.
(My knowledge of physics is sketchy & old but has been supplemented by
science fiction, some written by very able mathematicians & physicists!)