Light (photons) is emitted from stimulated electrons (electrons that have absorbed various photons) when the overall energy level reaches one of the energy levels for which a given photon can be emitted. (When a photon interacts with an electron, the interaction can be exclusive (the photon is deflected) or inclusive (the photon is absorbed). The emission points, being bound to certain energy levels, prevent in-between-point emission; so, no photons of m/n where n is a whole wavelength and the fraction m/n is not the length of a full-but-shorter (or full-but-longer) wavelength.) (I'm assuming that the electron-specificity is actually particle-neutral; i.e. a proton or neutron or quark that is similarly stimulated will emit discrete wavelength photons even if the individual absorbtions are not contained in the set of that particle's emission points.)
So, that explains lasers. (And probably radiant gases where the radiance is due to heating.)
Heat, when retained, is generally the energy the does not fall within the material's emission points. ("Material" is shorthand for "substances, elements, particles, and subparticles".)
As to space-time validity, it being false is unlikely.
We perceive in linear progressions (at least, I do, and most seem to, based on their responses) and not cyclical or recursive ones. I've yet to see any evidence of someone sharing gobbledygook at moment X that N years later is an exact quote of a recent discovery. (I've seen something similar, but, regretfully, I lack the means to prove it. So, I'll not admit to the details here.) I've seen lots of evidence of persons sharing a new view after having had time to run across a dissenting view from the respective persons' older view. That process is inherently time-driven.
Space is what we operate in. In effect, space is the medium within which our constituent parts move and interact. A falseness of space leads to recursive thinking about meaning and, dare I borrow the concepts, brains in caves or bottles. (Interestingly, my brain tends to hurt when I peruse my thinking processes while using my thinking processes and trying to prevent either group of processes from influencing the other group or being influenced by the prevention processes. So, forgive me for forgoing such thinking.) Absent an extensive philosophical discussion of the correllaries and connotations of what perception is and how to prove it is not, I find myself unable to argue about the validity of the falseness of the background medium. (And I'm unwilling, at this time, to have that discussion.)
I'll acknowledge that I've not argued well for the space aspect of space-time. But, most* of the evidence I have points to the linearity of time.
Kindergarten science is a person saying, "I have this great thought. I know it's true. I'll prove it.". Later, the person says, "I thought about it and it feels right, so it must be so".
Modern science is supposed to be a person saying, "I have this great thought. I'm sure it's true. I'll prove it with this research and these correlations". Later, this person states, "I did this initial research and discovered these constraints. So, I refined the experiment and used much more rigorous procedures and recorded the results as diligently and dispassionately as I could manage and discovered the following." And then lays out the experiments, the constraints, the results, the intermediate results, the reasoning for the constraints, and an interpretation of the results. When some later person does the same experiment, the new results either support or refute (or a mix of both) the original results.
I'll acknowledge that much of modern science is research in pursuit of point of a hypothesis, with the end goal shifting as portions become invalid or unlikely. I'll also acknowledge that much research is "I/We/You have an idea. Let's see what I/we/you can turn up to prove/disprove/expand/shrink the idea." The former is grade school science; the social aspects of shame permeate the process. The latter is still science. One might argue that the latter is a foundation of science - research for information's sake.
PS: In all honesty, I am not the best person to argue linear time, as I have experienced events that can't be proven but probably disprove the adherence of everything (although not most things) to a linear time. The can't-be-proven aspect addresses the difficulty in doing the impossible to prove the improbable with evidence that may no longer exist. So, "most" is what I can offer, because "the rest" has problems associated with it.