Anti-Gravity from Matter-AntiMatter Repulsion

[sanman]

Then why do we see lots of matter in our universe, but almost no anti-matter?

 

[Max™]

I think that has to do with the production rate of certain mesons which tend to shift into matter slightly quicker than antimatter.

 

[sanman]

The production of anti-hydrogen offers the opportunity to test/verify whether anti-matter will fall up or down in our Earth's gravitational field:

http://www.technologyreview.com/blog/arxiv/26709/?p1=Blogs

I realize that some of you may find the idea of verifying this to be silly, but there have been many experiments done in the past to verify known physical laws down to very fine levels of precision. This experiment seems quite doable - after all, if you can produce the anti-hydrogen, then it's just a matter of seeing which way it falls in our Earth's gravitational field.

When people use things like Schwarzschild radius to mathematically derive whether there is attraction vs repulsion, the logic-pitfall I'd worry about is circular inference. By this, I mean that the math is itself derived from observations which have only been done on matter, as opposed to antimatter. Therefore if observations aren't sufficiently comprehensive to have included antimatter and any uniquely different behavior, then the resulting mathematical description would be similarly lacking.

Anyhow, no one has yet explained the reason or mechanism behind the asymmetric production rate of the B-besons. Who's to say that this isn't somehow correlated or causally linked to our Earth's gravitational field? (ie. the result of the particular distortion of spacetime caused by a large body of matter, as opposed to anti-matter)

 

[sanman]

The next thing I'd like to ask about is the Equivalency Principle.

The Equivalence Principle says that a man inside a closed elevator will not be able to tell whether he is experiencing a gravitational field or whether the elevator is accelerating inertially.

Could the Equivalency Principle be extended to encompass anti-gravity as well?
If gravitational repulsion (aka. anti-gravity) is possible, then could we say that the man in the elevator will not be able to distinguish whether he is experiencing a gravitational field, or whether he is experiencing an anti-gravitational field, or whether the elevator is accelerating inertially?Case 1A) stationary elevator and man are made of matter, and are in the gravitational field of the Earth which is also made of matter

Case 1B) stationary elevator and man are made of antimatter, and are in the gravitational field of a planet which is also made of antimatter

Case 2A) stationary elevator and man are made of matter, and are in the repulsive field of a planet made of anti-matter (eg. anti-Earth)

Case 2B) stationary elevator and man are made of anti-matter, and are in the repulsive field of planet made of matter (eg. Earth)

Case 3) elevator and man are accelerating inertially in space, and there is no planet nearby exerting any fieldSo, what I'm saying is, shouldn't all these cases be indistinguishable, if indeed there is gravitational repulsion between matter and antimatter?

 

[PAllen]

The next thing I'd like to ask about is the Equivalency Principle.

The Equivalence Principle says that a man inside a closed elevator will not be able to tell whether he is experiencing a gravitational field or whether the elevator is accelerating inertially.

Could the Equivalency Principle be extended to encompass anti-gravity as well?
If gravitational repulsion (aka. anti-gravity) is possible, then could we say that the man in the elevator will not be able to distinguish whether he is experiencing a gravitational field, or whether he is experiencing an anti-gravitational field, or whether the elevator is accelerating inertially?Case 1A) stationary elevator and man are made of matter, and are in the gravitational field of the Earth which is also made of matter

Case 1B) stationary elevator and man are made of antimatter, and are in the gravitational field of a planet which is also made of antimatter

Case 2A) stationary elevator and man are made of matter, and are in the repulsive field of a planet made of anti-matter (eg. anti-Earth)

Case 2B) stationary elevator and man are made of anti-matter, and are in the repulsive field of planet made of matter (eg. Earth)

Case 3) elevator and man are accelerating inertially in space, and there is no planet nearby exerting any fieldSo, what I'm saying is, shouldn't all these cases be indistinguishable, if indeed there is gravitational repulsion between matter and antimatter?

The equivalence principle would be busted if antimatter were affected differently by matter. It's whole purpose is that inertial mass and gravitational mass are indistinguishable, so you can't distinguish being held stationary near a massive body from being accelerated in empty space. If antimatter acted opposite matter, all you need is a piece of each to tell the difference. If they move opposite, you are in a gravity, if they move the same, you are accelerating.

Note that the fact that protons and anti-protons have the same inertial mass is established to high precision (think, e.g. proton - anti-proton colliders).

Thus all known theories of gravity (not just GR) would be discarded if antimatter anti-gravitated. I'm sure someone will test this, simply because experimental physiscists like to test everything, as they should.