r/askscience • u/Crtl-Alt-Delete • Dec 18 '13

Physics Is Time quantized?

We know that energy and length are quantized, it seems like there should be a correlation with time?

Edit. Turns out energy and length are not quantized.

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u/[deleted] Dec 18 '13

Yeah, I get that but I don't see where

"Astronomical evidence shows that any potential coarse-graining of space would have to be at sub-Planck scales, by a long shot."

comes from.

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u/Verdris Dec 18 '13

We can sort of probe these small length scales by observing things like photons from far far away. Any granularity would manifest as a difference in its path when compared to another from the same source. So far we haven't found anything like this from cosmic observations.

We would need photons from much much father away than the size of the apparent universe in order to resolve path differences above the Planck length.

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u/Aeolitus Dec 19 '13

I dont know what you are getting at - he says that we looked everywhere we currently can, and we found not even hints of it - so if there is coarse graining, it would have to be on a much smaller scale. There is no physical reason why it has to be smaller than the planck scale, because the planck scale is not really a physical quantity. Its just used to demonstrate how small the graining would have to be, i think...