> Planck time […] is the smallest time step that present-day physics makes predictions about What are those predictions? Do you mean that > we know that it mu

> Planck time […] is the smallest time step that present-day physics makes predictions about What are those predictions? Do you mean that > we know that it must break down at Planck time ? If so, do you have a source for this prediction? (I'm not asking why present-day physics must break down at extremely small scales. That prediction is more or less well established. What I'm asking is: Why is it the Planck scale that's so significant?) My impression was that most statements involving the Planck scale these days are rather numerology than actual, verifiable science [1]. [1] https://physics.stackexchange.com/questions/185939/is-the-planck-length-the-smallest-length-that-exists-in-the-universe-or-is-it-th https://physics.stackexchange.com/questions/185939/is-the-pl...