# How do philosophers expain change if time is discontinuous?

How do philosophers explain discontinuous time? I don't mean how do they account for it, but how do they show what is meant by the term. What is meant by it? Specifically, how do they account for changes in tense? Mellor, Real Time 2. This is the common sense understanding of A times.

And, supposing that B times are not discontinuous, but A times are, does that mean the present does not end (nor begin)?

This ideas seems to follow quite sensibly from the bold, so I'm just asking if anyone takes this route.

e.g., if a continuous interval is divided by an instant T along it, and that is discontinuous with that interval's end, surely that instant T necessarily belongs to the interval ending at that time T. Any instant belongs to an extended "now" before it, and so does not belong to the beginning of the interval after it.

What is after the present never begins (and likewise what is before the present never ends).

• sorry if this is a duplicate, esp if closed
– user38026
Jan 31, 2020 at 14:43
• I mean, there are physical limits like the Planck second which indicate the minimum time intervals it’s actually possible to experimentally measure... Jan 31, 2020 at 14:57
• i guess @JosephWeissman
– user38026
Jan 31, 2020 at 14:58
• Maybe you could unpack a little further what exactly you're looking exactly for here? (Is there something in specific you're reading or studying that might have made this an important or interesting question? What does a great answer to this look like in your mind??) Jan 31, 2020 at 15:17
• "The Planck constant is related to the quantization of light and matter." Ref.1 Its use in the definition of Planck time does not mean that time is discontinuous. Good question though. "Because the Planck time comes from dimensional analysis ... there is no reason to believe that exactly one unit of Planck time has any special physical significance." Ref. 2. Jan 31, 2020 at 15:23

First, one should realize that the nature of time is a poorly understood subject, and there are good reasons to reject each of A time, B time and growing time models. See my answer to this question: The passing of time

Neither A time nor B time is readily discretized to become discontinuous. In A time, there really isn't any time, so it shouldn't be discrete. What would be discretized would be state changes, and what it means to set a minimum state change step size -- does not seem coherent. In B time, time is spacialized, and just integrated with geometry. And geometry is not discrete.

The efforts by physicists to evaluate what would happen if space and time were both discrete, are discussed in these physics SE answers: https://physics.stackexchange.com/questions/33273/is-spacetime-discrete-or-continuous

What they have shown is that so far, the experiments show no discreteness. Plus the Weyl's tile argument applies to both Pythagoras's theorem, and to the concept of momentum -- we would need to rebuilt the basis of classical physics and geometry somehow if the substrate of time and space is discrete. We know that both are only approximations, so this is not a killer argument, but we know how to get to both with continuous time and space, but not discrete, so this is a pragmatic objection to discreteness.

• but isn't saying "there isn't really" kinda shorthand to absolving the responsibility of answering a question?
– user38026
Jan 31, 2020 at 20:04
• Time models are an effort to match what we have discovered about time. The reason we have three is because they are each insufficient -- IE refuted or broken in some cases. Applying those models to a circumstance that violates a core presupposition -- will break them more profoundly. Using a model in an area that you know it does not work -- will not give valid predictions! I showed that your 1, 2A, and 3 don't make sense, because you are misunderstanding A time. 2B is correct in B time and discrete time. 4 is incorrect, discrete time will not reorder B time. 5 is always true of A time. Jan 31, 2020 at 21:08
• But ultimately, the whole series of questions presupposes BOTH B and A time are valid, when they are mutually exclusive. Jan 31, 2020 at 21:32
• A time considers time to be a logic state, and past and future are invented artifacts, while present is the only thing that exists. B time holds that time is a dimension, the past and future exist,and the experience of the present is an illusion. C time is a modificaiton of B, in that it dimensionalizes time, but holds that the past is the part of time which is real, future is invented, and present is -- just a boundary case, while pesentism and its logic model are untrue. These three are incompatible. If you think otherwise, do you have any links? Feb 2, 2020 at 18:43
• Practical empiricism accepts that sometimes we don't have globally valid models, but that we can have a locally highly useful model. A, B, and C models of time are incompatible, but each is highly useful in understanding some aspect of time, and help us in some usages of time. Our understanding of time is not complete, and using each of these models outside their range of applicability will lead to gross errors. But we still can understand and deal with time under most circumstances, hence our understanding is not "completely incoherent". Feb 2, 2020 at 21:51