For all practical purposes, they kind of appear to be: https://en.wikipedia.org/wiki/Planck_length https://en.wikipedia.org/wiki/Planck_length https://en.wiki

For all practical purposes, they kind of appear to be: https://en.wikipedia.org/wiki/Planck_length https://en.wikipedia.org/wiki/Planck_length https://en.wikipedia.org/wiki/Planck_time https://en.wikipedia.org/wiki/Planck_time