Mathematically speaking, you can say "in average it travelled for 1 Planck length in 1.5 Planck time". But physically speaking, it doesn't mean anything. Quantum mechanics works with wavefunction. Objects don't have an absolutely precise position. To know where the object is, you need to interact with it. To interact with it, you need something to happen. Due to Heinsenberg's Uncertainity Principle (even if you consider it as a "certainity principle" as Eliezer does), you just can't locate something more precisely in space than a Planck length, nor more precisely in time than a Planck time. Done at quantum level, objects don't have a precise position and speed. So saying "it moves at 0.75c so it crosses 1 Planck length in 1.5 Planck time" doesn't hold. It can only hold as an average once the object evolved for many Planck times (and moved many Planck length).

Mathematically speaking, you can say "in average it travelled for 1 Planck length in 1.5 Planck time". But physically speaking, it doesn't mean anything. Quantum mechanics works with wavefunction.

I see. But this raises again my original worry: does QM's claim about Planck times actually say anything about the continuity of time? Or just something about the theoretical structure of QM? Or just something about the greatest possible experimental precision? Does a limit on the precision of time at this level imply that these are actual indivisible and discontinuous units?

Mathematically speaking, you can say "

in averageit travelled for 1 Planck length in 1.5 Planck time". But physically speaking, it doesn't mean anything. Quantum mechanics works with wavefunction. Objects don't have an absolutely precise position. To know where the object is, you need to interact with it. To interact with it, you need something to happen. Due to Heinsenberg's Uncertainity Principle (even if you consider it as a "certainity principle" as Eliezer does), you just can't locate something more precisely in space than a Planck length, nor more precisely in time than a Planck time. Done at quantum level, objects don't have a precise position and speed. So saying "it moves at 0.75c so it crosses 1 Planck length in 1.5 Planck time" doesn't hold. It can only hold as an average once the object evolved for many Planck times (and moved many Planck length).I see. But this raises again my original worry: does QM's claim about Planck times actually say anything about the continuity of time? Or just something about the theoretical structure of QM? Or just something about the greatest possible experimental precision? Does a limit on the precision of time at this level imply that these are actual indivisible and discontinuous units?