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Referring to Arnold Neumaiers answer here, where he states that:

"If time appears discrete (or continuous) at some level, it could still be continuous (or discrete) at higher resolution"

This seems to imply that a measurement of a discrete space-time at some resolution does not imply "fundamental" discreteness and hence discrete and continuous space-times are equivalent descriptions.

So I would like to know:

(How) Can a continuous (space-) time look discrete on a LARGER scale?

i. e. how could (space-) time at (1cm) 1s resolution look discrete while being continuous at a (1mm) 1ms scale?

Qmechanic
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1 Answers1

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"If time appears discrete (or continuous) at some level, it could still be continuous (or discrete) at higher resolution"

This seems to imply that a measurement of a discrete space-time at some resolution does not imply "fundamental" discreteness

This is correct - there can be detail which is continuous but which you have not the ability to resolve and hence only see an apparently discrete change.

and hence discrete and continuous space-times are equivalent descriptions.

This is not necessarily the case.

We don't really know the consequences of such discrete space-time, but we would presumably reach a point at which resolving differences between discrete and continuous is possible. Put crudely, you'll notice an edge.

However we would expect a discrete space-time to have a limiting case (when considered at a large enough scale) to match our continuous models, simply because we know those models work well at the appropriate scales.

So I would like to know:

How can a continuous (space-) time look discrete on a LARGER scale?

The argument is fairly simple. Imagine on a very detailed scale (a small scale) a graph has a level region which then develops a very steep (but continuous) slope to a new level.

Now "zoom out". Zooming out the steep slope stops looking like a slope and starts appearing like a vertical line. You cannot, with measuring tool scaled to that level of "zoomed out" detail, resolve the co0ntinuous slope from one level to another and it appears simply as a sudden change from one discrete level to another - a step.

So at a larger scale it can seem discontinuous, but on a more detailed, smaller scale, it can appear continuous.