Gravitons are still only hypothetical, so, assigning any physical properties to them is mythical.
That's not how science works either. It's not "myth," it's the prediction of a theory formulated to explain known facts. In order for a predicted particle to be consistent with the facts we have, it must behave in a certain way, and must
not behave in any way that would contradict those facts. For instance, if a particle's mass were above a certain level, we would've seen evidence of it by now, so we know it must be less massive than that if it exists. (Indeed,
recent investigations of whether gravitons could have mass have ruled out anything above an extremely tiny mass.) So even if we haven't confirmed a particle's existence, that doesn't make its properties a crapshoot. We can narrow in very precisely on what range of properties it could have if it existed.
It's the same as if you didn't see a murder being committed but can reconstruct the details of how it had to happen based on the physical evidence at the scene. The blood spatter pattern tells you the shot had to be fired from a certain position, by a shooter between 5' and 5'3". The victim's position tells you they were facing the shooter rather than fleeing, and there's no sign of forced entry, so you know they knew and trusted the killer. There are burned-down candles and champagne glasses on the table. The striations on the bullet tell you it was fired from a type of small revolver designed to be carried in a woman's purse. And so on. So you don't know exactly who the killer is, but you can rule out all the suspects and scenarios that don't fit the facts you have. If you say the killer was a woman that the victim was seeing romantically, that's not a "myth," and it's not on an equal footing with the theory that the killer was a 7-foot shotgun-wielding burglar who broke in by force. You don't know exactly who the killer is, but you can absolutely say who it can't possibly be. That's how you arrive at a theory of the case in the first place, by ruling out what doesn't fit the facts and narrowing in on what's left. And physics works the same way.
In any event, per Wiki, the graviton is called "an elementary particle that mediates the force of gravity", so, if it is
a particle, then why can't treknobabble capture them? Sounds easier than capturing a photon.
Not all particles are alike. There are two different categories, fermions and bosons, that behave differently. Fermions are what we usually think of as "matter" particles, things like protons and electrons, while bosons are things like photons and force exchange particles that behave like what we think of as "energy," in that they can pass through each other without interference, be emitted out of fermions or absorbed into them, etc. Two fermions can't exist in the same place/state at the same time, so they're "solid" -- they just bump into each other and can't get any closer, so to speak. But any number of bosons can overlap in the same state, so they're "intangible" and mutually indistinguishable. (In some special cases you can make fermions behave like bosons -- a Bose-Einstein condensate -- but they have to be incredibly cold and the conditions have to be exactly right, and it generally doesn't persist for long.)
Indeed, when you see light through a pane of glass, the photons that reach your eyes are not the same ones the light source emitted. The particles of the glass (and the intervening air) absorbed the original photons and emitted identical ones. But because the distinction between bosons is irrelevant, unlike the difference between fermions, they can be treated as a single continuous beam of light. They're ephemeral in a way that fermionic particles like electrons and protons are not.
The word "particle" or the word "wave" is only an analogy for subatomic objects that have properties similar to both. When we say "particle," we're thinking of something like a grain of sand, and when we say "wave," we're thinking of something like a ripple in water. Something like a proton or a graviton has aspects of both, but a proton is closer to the "particle" side and a graviton is closer to the "wave" side. It's generally more useful to think of electromagnetism and gravity as waves in the energy fields that pervade the universe. Really, all particles can be considered defects or discontinuities in those fields, but fermions are more persistent defects.
To be more specific, things like photons and gravitons are force exchange particles. Their "job," as it were, is to transfer energy between other particles. So you don't "store photons," you absorb the energy they transmit, whether as stored electrical charge or as heat or whatever. The photon ceases to exist once it's delivered its energy to the fermion that absorbs it. And gravitons presumably do the same once they've delivered their gravitational energy. They're like power-up or health-boosting objects in a video game, in that they vanish once you've absorbed them, rather than being stored in your backpack or whatever for later use. They aren't retained, only their energy is.
