this post was submitted on 15 Feb 2024
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Reposting bc I dun goofed before

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[–] Blue_Morpho@lemmy.world 4 points 9 months ago (1 children)

Plank time is arbitrary too. Plank time is the time it takes light to move 1 Plank length. It's no different than any other time measurement other than it's the shortest measurable unit of time.

[–] GreyEyedGhost@lemmy.ca 3 points 9 months ago (1 children)

How is the shortest measurable amount of time it's possible to measure with the physics of our universe arbitrary?

[–] Blue_Morpho@lemmy.world 2 points 9 months ago (1 children)

It's arbitrary in the same way measuring the time between photon absorption/emission in a cesium atom is arbitrary or the rotation of our planet is arbitrary.

Picking the smallest is arbitrary just like picking a larger interval.

In the cesium clock case, you count 9192631770 because it's close to 1 second we already are familiar with and arbitrarily say 9192631770 transitions is defined as 1 second.

For example Planck time is defined as 5.391247(60)×10−44 seconds. But what is that second? It's the arbitrary 9192631770 cesium transitions we picked because it's close to the second that come from Earth's spin.

[–] GreyEyedGhost@lemmy.ca 3 points 9 months ago

Planck time doesn't appear to be arbitrary, but a feature of our universe, hence the shortest measurable unit of time. It's length in seconds is arbitrary because seconds are arbitrary. And seconds are arbitrary because the only non-arbitrary unit of time we have found so far is too unwieldy to use for anything but scientific purposes, and it's very unwieldy for many of those.