&gt;  The uncertainty principle hints that something discrete may lie at the bottom.<p>Not necessarily. The uncertainty principle is a direct consequence of some quantities being &quot;the Fourier transform&quot; of each other. You can&#x27;t play a pure tone unless it extends infinitely in time, and vice versa: You can&#x27;t play an infinitesimally short sound unless you ring all frequencies. That&#x27;s all.<p>And actually, if something discrete lies at the bottom of spacetime, the uncertainty principle implies that there&#x27;s a maximum energy and a maximum momentum. For the same reason that there&#x27;s a Nyquist frequency when sampling. So, if anything, our intuition that there aren&#x27;t such maxima makes the uncertainty principle hint that there&#x27;s nothing discrete underneath.