# Is Space-Time Quantisation necessary or even meaningful?

It is believed among people working on Quantum Gravity, that space-time must be quantised at the Planck scale. Although it is very hard to verify such proposition, it is interesting from a philosophical and epistemological point of view.

According to this view, no spatial or time interval shorter than the Planck values exist:

For length: $l_p=\sqrt{\frac{\hbar G}{c^3}}\sim 10^{-35}$m

For time: $t_p=\sqrt{\frac{\hbar G}{c^5}}\sim 10^{-43}$s.

Let us assume there is no structure smaller than $l_p$, and let us imagine some kind of cube of side $l_p$. This cube must be distinct and “distinguishable” from other similar cubes around it. For this to be possible, and for the cubes to be able to display some dynamics, something in the form of continuous space must stand in between these cubes.

Question:

If the above reasoning is correct, then, what is the meaning or need for space-time quantisation?

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one can find analoges to processes which exhibit characteristic lengths or durations (or frequencies), indeed the birth of QM was the fact that atomic spectra are dicrete (frequencies discrete/quantised/characteristic, orbits quantised/charactesrictic, etc..) – Nikos M. Nov 2 '14 at 16:56