If you’ve ever watched the old or modern versions of Quantum Leap you know the routine: a “leaper” is time traveling by temporarily taking over the body of someone in the past, while another person from the traveler’s own time is supporting them remotely as a projected hologram only the time traveler can see and hear. The hologram can’t touch anything or communicate with anyone except the leaper in the past, but can zap around the past like a ghost to experience events without affecting anything directly.

I’ve always thought that if you invented the hologram part of the Quantum Leap time travel scheme, you wouldn’t need the actual bodyswap time traveler part at all. You’d already have the safest possible form of time travel! You could remotely visit the past in hologram VR without accidentally stepping on a butterfly, changing winners of wars, dating your own mom, or otherwise screwing up the timeline in all the ways in which time travel scifi portrays. You could safely be an invisible time tourist from home all you wanted.