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Is time consecutive in physics? Here is my deeper explanation of what I mean. Are frames for example in a camera a good metaphor with the concept that time also has "frames" in the space of our universe. I am posting here for the first time, hopefully I am not asking the same question.

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    $\begingroup$ Are you asking if time is a continuous or a discrete variable? $\endgroup$ – Qmechanic Dec 2 '20 at 15:44
  • $\begingroup$ Do you ask about the causality? $\endgroup$ – Vadim Dec 2 '20 at 15:49
  • $\begingroup$ Yes I am, thanks for correcting (Qmechanic) $\endgroup$ – Martin Dec 2 '20 at 15:49
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    $\begingroup$ Does this answer your question? Is time continuous or discrete? $\endgroup$ – John Rennie Dec 2 '20 at 16:31
  • $\begingroup$ Indeed it does. $\endgroup$ – Martin Dec 2 '20 at 16:58
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The traditional answer (in classical physics) is that the instants of time and places in space that we can observe and measure are continuous variables (all are smoothly connected) rather than being discrete (where they jump instantaneously from one value to another nearby, like the frame refresh in a film projector or a computer screen).

Some hypothesized models for the quantum universe (specifically, some of those that attempt to unify gravity with quantum physics) posit that both space and time actually come in discrete chunks, but that those chunks of space and time are so incredibly tiny that to the limit of all our measurement capabilities, they still appear continuous.

At present there is no experimental evidence in hand that supports the idea that space/time is structured out of indivisible quanta, and because the time and length scales at which those quanta could be detected are so very, very small, it is unlikely that humans will ever be able to directly observe or measure them in any experiment we could possibly devise.

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  • $\begingroup$ Also note: The human race has invested an enormous amount of effort in developing the mathematics of continuous spaces. We probably would continue to use that math for a looooong time, even if it were proved that time and space were discrete. $\endgroup$ – Solomon Slow Dec 2 '20 at 16:03
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Not quite.

The notion of sequential events works well enough in classical physics, where all observers agree on the passage of time and the sequence of events - we can all see that events A, B, and C, happen sequentially at different times, in different "frames" of the film (although it should be noted that there are not really "frames" in the sense of discrete, indivisible chunks of time - nature does not like discontinuities, so you can't jump from position X to position Y without passing through every point in between). But this view of simultaneity breaks down in relativistic physics, due to the relativity of simultaneity.

When events occur at different locations, it's actually possible for different observers moving at different speeds to disagree about the sequence of events. One might see that events A and B occur at the exact same moment, while another sees that event A occurs before event B, and both are correct from their point of view. So, we can see there is not some single "film" of events that we can consult to view things through time. In one person's version of the film, events A and B occur in the same frame, but in another person's version of the film, they do not. Events that are simultaneous to one observer may be sequential to another, so the view that there is some fixed, master version of "consecutive" events is incorrect.

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  • $\begingroup$ When the OP refers to "frames", I believe he's asking whether spacetime could consist of granular bits, not whether there is a preferred time-order for those bits. I might of course be wrong, but if I'm right then relativity of simultaneity is not a relevant issue here. Relativity works perfectly well over any field where $-1$ is not a square, including the rational numbers or any finite field of characteristic congruent to 3 mod 4. So relativity of simultaneity certainly does not preclude "granularity" or even discreteness. $\endgroup$ – WillO Dec 2 '20 at 16:16

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