Topics Time

Question In the first Superman movie, after Lois Lane is killed in the earthquake, Superman appears to reverse time by flying around the Earth and reversing its rotation. Thinking about it, this makes no sense. But in the movie, it has a certain plausibility. So what gives Superman's feat its plausibility? (A friend of mine suggested that the Earth didn't actually reverse its rotation due to Superman flying around it, but that the reversing rotation was just meant to suggest that Superman, by flying so fast, was able to go back in time himself. But this, too, makes no sense.)

Accepted:
December 15, 2005

Comments

You are right that Superman's feat of resurrecting Lois Lane makeslittle sense. The same is true of nearly all films (or stories)involving time travel. The trouble arises when characters 'change thepast'. That whole idea is of doubtful consistency. If Superman makes itthe case that Lois didn't die yesterday, then how come we saw a realityin which she got squashed by the earthquake? Maybe some sense can bemade of this by supposing that reality has a branching structure, andthat Lois dies on one branch but not the other. But even this doesn'tseem to do the trick. Isn't Superman supposed to be saving Lois, not just adding something to a structure in which she is also still squashed?

Analternative would be to suppose that Superman (and we viewers) inhabita Supertime, such that at Superdate 1 ordinary reality contains Loisdying yesterday, but by Superdate 2 Superman has changed ordinaryreality so that Lois survived yesterday. This is no doubt how weunderstand the movie, and why it seems plausible enough at first pass.But I'm not sure that even this really makes sense. (For a start, howexactly do Supertime and ordinary time relate to each other?)

All the above puzzles come from the idea of 'changingthe past'. By contrast, that is nothing immediately incoherent in theidea that the past is (and always has been) influenced by a travellerfrom the future. (Thus Mack Reynolds' classic story 'CompoundedInterest' (1956): a hugely rich man uses most of his fortune to build atime machine in which he then goes back 500 years to depoisit 1 ducatat compound interest so that in 500 years time . . .)

Still, once we admit time travel itself, won't the more paradoxical ability to changethe past inevitably be admitted too? If I can go back to the past,what's to stop me killing my own grandfather? It is a matter of currentcontroversy among philosophers whether the apparent freedom of a timetraveller to cause such paradoxial consequences shows that the idea oftime travel itself is incoherent. (What about the episode of Futuramawhere Fry does accidentally kill his own grandfather, and then consolesthe bereaved fiancee, and walks her home, and stays the night . . .?But of course that wasn't then his real grandfather that he killed.)