Fireworks are only possible because of quantum physics

When that first energy release occurs, conventionally known as the lift charge, it has two important effects

The lift charge imparts an impulse, causing an acceleration, to the remainder of the firework, which includes the other three components.

This upwards acceleration needs to give your firework the right upwards velocity to get it to a safe height for the explosion, and the fuse needs to be timed appropriately to detonate at the peak launch height.

When you apply enough energy to an atom or molecule, you can excite or even ionize the electrons that conventionally keep it electrically neutral. When those excited electrons then naturally cascade downward in the atom, molecule or ion, they emit photons, producing emission lines of a characteristic frequency. If they fall in the visible portion of the spectrum, the human eye is even capable of seeing them.

What determines which emission lines an element or compound possesses? It’s simply the quantum mechanics of the spacing between the different energy levels inherent to the substance itself.

As applied to fireworks, there are a great variety of elements and compounds that can be utilized to emit a wide variety of colours. Different compounds of Barium, Sodium, Copper and Strontium can produce colours covering a huge range of the visible spectrum, and the different compounds inserted in the fireworks’ stars are responsible for everything we see.