Can Anti-Matter Generate Anti-Gravity?

The question has been asked, why doesn't anti-matter generate anti-gravity on the same grounds and for the same reasons that matter generates gravity? My general answer, albeit speaking as a lay or non-expert, is that there's no causal association between positive or negative electric charge and positive or negative (anti) gravity. This means that there can be no actual establishment of a Theory of Everything (TOE).

What is anti-matter? It's just a matter particle that has an equal but opposite electric charge associated with it. The common example is the negative electron and the positive positron. A positron is the anti-matter electron. Some particles are their own anti-particles. A neutrino and an anti-neutrino are the same thing. Ditto a photon and an anti-photon are one and the same thing. Presumably the theoretical (as yet undiscovered) graviton and anti-graviton would be the same thing. If an anti-graviton would be the same thing as a graviton, and a graviton is the pull force that manifests itself as gravity, then there is no anti-gravity push force.

Electric charge would seem to be something fundamental - a fundamental property of whatever object has electric charge. I mean you couldn't remove electric charge from an electron (or a positron) and still have an electron (or a positron).

What actually is electric charge? We know the push / pull properties of electric charge but not much else. It would be interesting to know the ultimate causality that generates electric charge. Why does electric charge of necessity exist at all as something fundamental? And why is electric charge in just-so units and why is it associated with just certain types of particles (i.e. - electrons) and not with other types of particles (i.e. - neutrinos)?

As noted above, an electron and a positron differ only with respect to electric charge and electric charge wouldn't seem to have any effect on gravity or gravity on electric charge. Presumably an electron (or a positron) is still an electron (or a positron) regardless of what strength gravitational field it is in. An electron is an electron is an electron when it is weightless (in zero-G); in micro-gravity (weak-G); in standard Earth-G; in really strong-G or even inside a Black Hole.

When an electron and a positron meet and greet and go Ka-Boom, you don't get equal amounts of energy and of anti-energy; just energy.

If you accelerate an electron to ever faster and faster velocities, its mass, hence its gravity must increase according to Einstein's Relativity theories. But, the electron's electric charge wouldn't change at ever increasing velocities, so there's no apparent relationship between an electron's gravity and an electron's electric charge.

Now you might argue that the apparent acceleration of the expansion rate of the Universe must be put down to an anti-gravity push force (which goes under a host of pseudonyms like dark energy or the cosmological constant). However, there's no apparent association between dark energy and anti-matter. In fact I would argue that an acceleration of the expansion rate of the Universe is downright and flatly impossible since it involves creatio ex nihilo otherwise known as the creation of an absolute something from an absolute nothing which is a violation of the First Law of Thermodynamics. In other words, my cosmology texts tell me that the energy density of the Universe remains constant even though the Universe is expanding, whereas one would expect the energy density to decrease as in an expanding Universe energy becomes more dilute. So an accelerating expansion rate of the Universe is just plain nuts and IMHO an example of 'special effects' generated by computer software. I mean at the point of the Big Bang event, there was a finite and supposedly fixed amount of matter / energy within. So where is this extra energy coming from? Perhaps it's just an artificially generated simulation.

Anti-matter is mysterious quite apart from the cosmological puzzlement that there should be equal amounts of matter and of anti-matter in the Universe and that doesn't seem to be the case. The other mystery IMHO is when an electron meets and greets a positron, why not get a resulting particle with no overall electric charge and twice the mass or either an electron or a positron?

Another mystery is why does an electron and a positron go Ka-Boom when they meet and greet but not an electron and a proton whose electric charge is also equal and opposite to that of an electron?

Overall conclusion: gravity versus electric charge (or electromagnetism). The idea that there is no actual causal association between gravity and electric charge is evidence for the Simulation Hypothesis. There is and can be no Theory of Everything (TOE) which is the theoretical unification between the realm of the micro (where electric charge resides) and the realm of the macro (where gravity resides) because there are two separate and apart pieces of software running the cosmos. One is for the micro; one is for the macro.

Addendum One

Of course to a physicist a Theory of Everything (TOE) isn't of course actually having to know everything. I mean a TOE doesn't have to incorporate things like legal and political systems, the rules and regulations involving sporting contests or concepts involving aesthetics. "Everything" to them as you correctly note, is just a unification of the micro and the macro; the unification of the four (known) fundamental forces.

I wouldn't want to say such a unification is "impossible", other than to note that thousands of the finest minds going, have for multi-decades now, tried to find a TOE - and to date failed to do so. Now if there is just one Mother Nature, then it just can't be that difficult to find an overriding commonality. Something is screwy somewhere!

Now there are two main reasons why I can't in the here and now at least accept a connection between anti-matter and anti-gravity. Firstly, some particles have no electric charge and thus are their own anti-particles. A neutrino comes to mind. But a neutrino, hence an anti-neutrino, has mass (and not anti-mass - whatever that would actually mean), hence gravity (and not anti-gravity). So gravity hence anti-gravity can't be dependent on electric charge. Secondly, anti-matter has been created in the laboratory and is used in medicine - Positron Emission Tomography (PET) comes to mind here. I don't recall any reports of said anti-matter shooting up skywards! Anti-matter would seem to obey the same physical laws, principles and relationships that rule the matter roost.

Something else is bothering me here. A particle and an anti-particle should attract each other since they have opposite electric charges. But say the particle has standard gravity (pull) and the anti-matter particle has anti-gravity (push). Or, you can imagine an overall electrically neutral object made of matter (that is composed of electrically neutral atoms and molecules) and an electrically neutral object made of anti-matter (that is composed of electrically neutral anti-atoms and anti-molecules). If both attract each other under the standard force of gravity, then there is no anti-gravity. But if the electrically neutral matter object had the standard pull gravity, and if the electrically neutral anti-matter object had anti-gravity - push gravity - then what? I mean then what given the two push and pull gravitational forces have the exact same magnitude? Do you have an equivalent to the immovable object versus the irresistible force? It all feels like a kind of contradiction that you just don't find in nature. I mean you just have pull-pull or push-push at least when it comes to electromagnetism, and just pull-pull when it comes to gravity. There are no equal and opposites at a distance pull-push (or push-pull) forces in opposition to each other.

Finally, if a neutral particle isn't its own anti-particle then the sum total of matter particles exceeds anti-matter particles. Neutrinos, photons, gravitons, etc. would be lumped in with the matter particles like electrons and up-quarks, but not with anti-matter particles. That would be a rather asymmetric situation that I'm sure particle physicists wouldn't accept.

So since a neutrino exists, and since a neutrino is its own anti-particle, if anti-particles generate anti-gravity, then a neutrino would have to exhibit both gravity and anti-gravity which would seem to be a contradiction.

Summary: Gravity doesn't seem to be linked to electric charge. Gravity, and anti-gravity if it exists, seemingly must have some other causal mechanism behind it.

Addendum Two:

A common objection would be, but isn't electric charge the property that makes anti-matter, well anti-matter? I mean what is the difference between an electron and a positron if not electric charge? And if electric charge is what makes anti-matter, anti-matter, and anti-matter has anti-gravity, then isn't electric charge somehow causally linked to gravity (which of course is what a TOE demands)?

If I had to place my bets, I'd still bet that while anti-gravity may in fact exist, electric charge will not be the causal factor. There's probably little point in endlessly speculating. Let the experiments begin, or continue - whatever.

Although this has relatively little to do with the question, I'm puzzled by what would happen if you had a Black Hole made out of matter, and a Black Hole made from anti-matter, and they collided, would you get 1) the Mother of all Ka-Booms, or 2) just a larger Black Hole?

By the way, one of the ideas behind the Tunguska, Siberia aerial explosion in 1908 was that it actually was a small chunk of anti-matter that impacted Planet Earth.