The idea starts with the zero point field or quantum vacuum and the fact that every point in space is constantly giving rise to pairs of particles. One is made of matter, one anti-matter. As soon as they come into existence though, they meet and annihilate one another.
The assumption that has to be made for this to work is that gravity is dipolar such that anti-particles have a repulsive gravitational field.
It’s already been experimentally shown that antimatter is affected by the Earth’s gravitational field in the same way as normal matter (or at least, in the same direction). For antimatter to produce a different field than matter, then, would require a violation of Newton’s Third Law, which so far as we can tell has no exceptions whatsoever for any phenomenon in the Universe.
Do you have a cite for that? According to the article which is dated Aug 2011: “Currently, it is not known whether matter and antimatter are gravitationally repulsive, although a few experiments (most notably, the AEGIS experiment at CERN) are testing related concepts.”[URL=“Dark matter may be an illusion caused by the quantum vacuum”]
When I read the paper on which the article is based the first thing that strikes me is that he doesn’t prove that the assumption of antimatter having negative active gravitational mass leads to a vacuum polarization that leads to a field described by Blanchet (who has claimed to have shown that a cosmic fluid of dipole moments has a field that can re-create the predictions of MOND and on whose work his paper is based). I might be missing something, but it seems his whole argument rests on proving this, but Instead he starts off with hand-waving arguments about virtual particles.
That is of course ignoring the fact that antimatter having negative active gravitational mass causes all sorts of theoretical problems (though as of yet it’s yet to be proven one way or the other experimentally).
My understanding was that the polarization only happens in the neighborhood of massive objects like stars. Then you get the attractive side of the fluid being pulled toward the star and that causes the polarization.
I don’t think you get any polarization in areas where there isn’t already some significant amount of normal matter.
A test of the equivalence in reaction to the gravitational field of matter and antimatter is provided by the observation of both neutrinos and antineutrinos produced by the 1987 supernova.
True enough, but if the neutrino were its own antiparticle, then antiparticles couldn’t very well have opposite mass with respect to their normal matter partners.
Hm, I could have sworn that I had seen an experiment where neutrons and antineutrons were put through an interferometer with one path higher than the other, so the difference in potential energy of the paths would change the interference pattern. I’m not finding it now, though.
I think that’s one of the motives they have at CERN for trying to make anti-hydrogen, so they have a stable source of anti-matter to use for such tests.
‘Antigravity’ per se isn’t necessarily incompatible with general relativity. General relativity is so general, admitting an extremely wide variety of solutions and if you ignore energy conditions (which wouldn’t have validity anyway if you accept the existence of negative mass) then you can obtain solutions where gravity is primarily a repulsive force I believe.
However there is direct observational evidence that antiparticles have positive inertial mass and I believe direct observational evidence that they have positive energy which presents probably insurmountable theoretical problems as viewing them as having negative active gravitational mass in a GR framework. Hajdukovic in particular postulates that they have positive inertial mass/passive gravitational mass, but negative active gravitational mass; I don’t believe this would be compatible with general relativity.
Perhaps the “Many Worlds” Theorem can be applied to gravity here.
EM radiates in 3 dimensions…does gravity radiate in 4D?
If gravity radiates sideways from parallel realities, could Dark Energy simply be the gravity of mass we do not directly have contact with?
I don’t know what “many worlds theorem” you’re referring to, but gravity diminishes as the inverse square of distance, just like electromagnetism, and just like you would expect for something that radiates out in three dimensions. There are models, including some very well-regarded ones, that have gravity propagating through extra dimensions, but they all need to jump through various hoops to recover the inverse-square law.
If the many worlds theorem is true…whenever a decision is made, each choice creates it’s own parallel universe…we could be feeling the effects of gravity from these alternate realities.
I can comprehend how an inverse square law applies to a 3d sphere…the shape of uniformly radiated energy…but what about a 4d hypersphere?