All science is materialistic

[Jehanne]

Some are photons, which are massless, but, since all photons travel, without exception, at the speed of light in a vacuum (speed varies, of course, in other substances with the frequency/wavelength), all photons have energy.

Here's the groovy thing:

Alice says the photon has x amount of energy.

Bob says the photon has y amount of energy.

Charlie says the photon has z amount of energy.

And they're all right, because the Hermitian linear operators we call "observables" are only real for the observer, who may be moving at varying velocities with respect to each other.

All those energies can be measured, observed, predicted, calculated; the explanations are materialistic; in using that term, no one is claiming that photons are a form of matter.