In his beautiful 2014 novel, Winter, Christopher Nicholson imagines Thomas Hardy, at the end of his long life, pondering the dead. They are lost to us, but might they continue to live, in their own time?

Time, if so, was not, as commonly thought, a process, but a series of metaphysical spaces. Ghosts were seen when, for reasons unknown, they inadvertently slipped from their allotted time into the present.

Was it possible that some advance in science, akin to the discovery of X-rays, would eventually allow the living to view a world crowded with noiseless, flitting ghosts?

I’d say so. Yes.