0

I was inspired by this wikipedia article invoking a notion of a "Supertask" (informally, an infinite sequence of operations performed in a finite amount of time) to pose Zeno's paradox.

To my understanding, the paradox is posed as this: since motion must cross half of the path between A and B, then half the path therein, and so on, motion is a Supertask.

My question is this: can't we apply the same halving argument to time, so that an infinite number of time-segments is used in the process of motion? Therefore, motion wouldn't be a Supertask. (A little more formally: if both time and 1-dimensional space are assumed to be segments of the reals, then any halving argument constructing infinite cells out of these segments can be applied to both time and space. Then we're only traversing an infinite sequence of cells of space in infinite cells of time, which is not a supertask.)

What's wrong with this argument? (Or, does it work?)

11
  • No. Since supertask is a countable sequence of actions performed in a finite interval of time, and the interval remains finite no matter how it is chopped up, it would still be a supertask. And even if we agreed not to call it that verbal relabeling does not solve anything. The solution is that imaginary chopping up of space does not create real actions in the first place, so motion isn't a supertask anyway. If Achilles had to actually wave his hand at each half marker that would be a different matter.
    – Conifold
    Commented Sep 24, 2020 at 20:09
  • Nothing wrong with it except that it contradicts known physics. You can speculate on future unknown physics though. That makes it science fiction.
    – user4894
    Commented Sep 24, 2020 at 20:53
  • Since Zeno's paradox is known to be wrong, it shouldn't be applied to time, or anything else.
    – D. Halsey
    Commented Sep 24, 2020 at 21:32
  • @Conifold but if we consider t_1 - t_0 a finite interval of time, can't we consider x_1 - x_0 a finite interval of space, which remains finite no matter how it is chopped up?
    – anand
    Commented Sep 25, 2020 at 0:53
  • Agreed re: zeno not reflecting known physics here. Just interested in testing the (abstract?) soundness of the original posed problem.
    – anand
    Commented Sep 25, 2020 at 0:56

0

You must log in to answer this question.

Browse other questions tagged .