"The Casimir effect is intrinsically a second quantisation effect, and cannot be "reduced" to something conceptually easy for the layman. Explaining what a quantised field is in few words is even more difficult."

Nope.

"first-quantization quantum mechanics (Heisenberg’s and Schroedinger’s first-quantization quantum mechanics, uncertainty principle making the world a matter of probability) went out of the window in 1927 when Dirac’s relativistic quantum field theory replaced it.

First-quantization is a lie: it treats the Coulomb field binding the electron to the nucleus classically, so the chaos of the motion of the electron has to be falsely introduced by making the electron’s motion intrinsically indeterminate. Second-quantization, as Feynman explains, gets rid of this application of the uncertainty principle because it simply treats the Coulomb field properly as a quantum field, in which field quanta (random discrete interactions) replace the false classical smooth Coulomb field.

The electron has a chaotic motion because the quantum electromagnetic field binding it in its orbit of the nucleus is chaotic, as Feynman explains:

“I would like to put the uncertainty principle in its historical place … If you get rid of all the old-fashioned ideas and instead use the ideas that I’m explaining in these lectures – adding arrows [path amplitudes] for all the ways an event can happen – there is no need for an uncertainty principle! … When we look at photons on a large scale … there are enough paths around the path of minimum time to reinforce each other, and enough other paths to cancel each other out.

But when the space through which a photon moves becomes too small (such as the tiny holes in the screen), these rules fail … there are interferences created by the two holes, and so on. The same situation exists with electrons: when seen on a large scale, they travel like particles, on definite paths. But on a small scale, such as inside an atom, the space is so small that there is no main path, no ‘orbit’; there are all sorts of ways the electron could go, each with an amplitude. The phenomenon of interference becomes very important, and we have to sum the arrows [amplitudes for different paths] to predict where an electron is likely to be.”

- Richard P. Feynman, QED, Penguin Books, London, 1990, pp. 55-85.

Well yes, if you find quanta being the 'ultimate answer' to the universe, life and all

Isn't it strange how every generation expect themselves to have solved the celestial motion of the infinite spheres

and all ..

Myself I think quanta exist, but I do not expect them to answer that final question, and I also expect a 'smooth' state hiding behind that. To me quanta is just one of the emergences we see, it's a fractal universe.