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Comment by criddell | Hacker News Reader

So, doesn't that suggest there's a Planck length for time? So the distance between two points in space-time is sqrt(x^2 + y^2 + z^2 - ct). If you try to find the distance of a point in space at two different times, does the Plank length dictate some type of Plank interval?

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Indeed. https://en.wikipedia.org/wiki/Planck_time

That page says the Planck time is the time it takes for light in a vacuum to travel one Planck length. That doesn't imply it's the smallest interval, does it?

Insofar as you can only really measure time as the interval it takes for something to happen, and insofar as light's travel is the fastest process in the universe, and that the plank scale is the smallest distinguishable distance, it follows that the measurement of time across that smallest interval is the shortest interval that can be reliably measured.

Doesn't that imply that every process in the universe proceeds in lock-step? If two virtual particles were to randomly pop into existence, does the time between the first and second particle appearing have to happen in some whole multiple of Planck time?

To my understanding, Planck time describes a limit on sample rate, not frequency. That is, we can't perceive time at a finer grain than whole multiples of Planck time. But even starting with only integers, we can theorize and simulate floats. The speed of light is as arbitrary a scale as anything else when you're talking about absolutes, hence "it's all relative".

Virtual particles actually exist for less than a planck unit of time. I'm not a physicist and I'm having trouble finding a good clear reference, but this page mentions it (cmd-f 'less than') - http://abyss.uoregon.edu/~js/ast123/lectures/lec17.html

That would be the chronon: https://en.wikipedia.org/wiki/Chronon

Well, if light (the fastest possible thing) takes this amount of time to travel the Planck length (the shortest possible thing), then does that not imply that nothing could possibly happen faster?

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