[Rade]

I would like to open a discussion on the following paper, where the claim is made of a new interpretation of CPT symmetry applied to General Relativity to show that gravity and antigravity forces must repel one another. Thus, if an antimatter apple had fallen from that tree, it never would have hit Newton.

http://iopscience.io..._94_2_20001.pdf

True or false argument, and why do you say so ?

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Thinking outside box, here is a simple model that we can apply to the predictions of this paper, to see if they would hold true. Suppose a 3-mass "matter" entity such as He-3 isotope [PNP] that responds to force of gravity of other matter entities. Next, suppose a 2-mass "antimatter" entity such as deuterium [N^P^]where ^ = antimatter. My question is, would not the predictions of the above paper demand that the two entities (one matter=[PNP], one antimatter=[N^P^]) would form a stable quantum superposition if their respective wavefunction came to overlap? The reason being that there would be an attraction between the two from strong force inertial mass interactions, but a repulsion using gravitational mass interactions, with a net effective of attraction (bonding) because the larger 3-mass [PNP] group was composed of matter. If not possible, please explain why not using the modified equations of GR provided in the above paper. {note: for this discussion we assume the argument presented in the paper is correct}.

[CraigD]

Rade, on 20 January 2012 - 10:26 AM, said:

I would like to open a discussion on the following paper, where the claim is made of a new interpretation of CPT symmetry applied to General Relativity to show that gravity and antigravity forces must repel one another. Thus, if an antimatter apple had fallen from that tree, it never would have hit Newton.

http://iopscience.io..._94_2_20001.pdf

True or false argument, and why do you say so ?

Villata’s paper is too technical for me to have a useful opinion of. Searching for something by someone better able to have an opinion, I found Marcoen J.T.F. Cabbolet’s Comment to a paper of M. Villata on antigravity. Cabbolet’s objections to Villata’s conclusion are also to technical for me to judge, but enough for me to conclude that Villata's argument via GR and CPT symmetry theory that antimatter and matter gravitationally repel should be considered tentative.

Far more straightforward, and thus more satisfying to me, are ongoing experiments to simply determine if matter and antimatter gravitationally attract or repel by making neutral antimatter atoms and seeing if they fall or rises in Earth’s gravitational field – to borrow from your phrase, Rade, to actually see which way an antimatter apple falls.

Nearly 3 years ago, in this post, I expressed optimism that CERN’s AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) collaboration would complete this experiment soon. Catching up at long last, I find that it’s still a work in progress, with no acceptable results yet. It would appear that shooting a stream of antihydrogen through a system of gratings to see by how it strikes them whether the stream falls up or down is harder than it sounds. And it looks so simple on paper!

[Qfwfq]

Rade, on 20 January 2012 - 10:26 AM, said:

I would like to open a discussion on the following paper, where the claim is made of a new interpretation of CPT symmetry applied to General Relativity to show that gravity and antigravity forces must repel one another. Thus, if an antimatter apple had fallen from that tree, it never would have hit Newton.

Firstly, you appear to be saying "gravity and antigravity" in lieu of "matter and antimatter".

Mostly, these opinions can be defeated quite simply, to a large degree of confidence, in a simple way, which was pointed out in a discussion of this issue a few years back. I'll sum up the argument here:

According to the well tested formalism which particle theory is based on, a photon's Fock space contains virtual charged fermion-antifermion pairs (mainly electron-positron) and it follows that a beam of high energy positronium ought to be affected by a gravitational field similarly to photon beams. Therefore, if these opinions were correct, a photon would be either unaffected by gravitation or it would get split into a pair of opposite charged fermions. Eddington's observation would not have matched up with GR. Likewise goes for a large fraction of the mass of hadrons, by way of gluons as well as photons and to a smaller extent the neutral weak bosons; hadrons can be depicted as full of mostly quarks and antiquarks, with the overall net being the two or three that you are typically told about. If these opinions about antimatter in gravity were so, the equivalence principle would simply not hold up in the least.

This post has been edited by Qfwfq: 27 January 2012 - 05:53 AM
Reason for edit: dumb typos

[maddog]

Rade, on 20 January 2012 - 10:26 AM, said:

I would like to open a discussion on the following paper, where the claim is made of a new interpretation of CPT symmetry applied to General Relativity to show that gravity and antigravity forces must repel one another. Thus, if an antimatter apple had fallen from that tree, it never would have hit Newton.

http://iopscience.io..._94_2_20001.pdf

True or false argument, and why do you say so ?

I kinda' liked Qwfwq's argument. Of course he seemed to ignore the article.
As for the paper. I read it. His introduction is clear. I start to loose it around the use of Tensor of various rank, and the usual "roof/cellar" notation that this field (GR) is so fond of. I accept in principle of the CPT Theorem argument. I would have to dig out my Misner,Kip,Thorne book on Gravitation and peruse through the Tensor Calculus to validate. I do question his conclusion (weak though it is). Even to the author, accepts this is not a "vindication" for Antigravity. The presumption near the end, I think is telling is the jump in his "interpretation" of what the "minus sign" means.

Even more intriguing is the authors speculation that a solution for missing Dark Matter could large sections of the universe be antimatter and thus not directly visible. This reminds me of a book I remember by Alven on Antimatter in 70s. The author of this book speculated something similar.

The other thing I thought odd is the author of this paper even acknowledges the conventional wisdom that a spin-2 graviton, being even be naturally attractive. I know this is probably derived from [M-Theory] or its current name. What I find odd is this just brings in another justification to poise yet another anomaly to shoot it all down. Odd.

maddog