science

Metaphysics has bigger questions to ponder and doesn't apply to physics. It's a branch of philosophy, not science.

And quantization was the solution to an even bigger problem in physics, the ultraviolet catastrophe.

We know that matter and energy are quantized because that's the only reasonable explanation for why blackbody radiation is distributed like it is. The classical Raleigh-Jeans law, which accurately predicts thermal radiation frequency at low temperatures, fails to do so for higher temps. Only quantizing the emission of photons produces blackbody radiation predictions which match our experiments.