Gravitation

[Oldman]

I have three questions. Your response will greatly help me in my research on gravitation.

 

(1) Do gravitayional masses of matter and antimatter have opposite signs?

 

(2) What's the sign of matter-antimatter gravitational force?

 

(3) Does General relativity alllow matter and antimatter to warp the field of space-time geometry oppositely?

 

 

 

 

[ajb]

As far as we know, there is no difference gravitationally between matter and antimatter.

 

(1) Do gravitayional masses of matter and antimatter have opposite signs?

 

No, both masses are positive and identical. (as far as we know)

 

(2) What's the sign of matter-antimatter gravitational force?

 

They will attract each other.

 

 

(3) Does General relativity alllow matter and antimatter to warp the field of space-time geometry oppositely?

 

I am not sure what is meant by oppositely, see my opening comment.

[steevey]

(3) Does General relativity alllow matter and antimatter to warp the field of space-time geometry oppositely?

 

 

 

 

 

No, I think your perception of anti-matter is highly obscured. Anti matter is not the complete reverse of normal matter in every way, its just material in which the nucleus of its atoms have a negative and neutral particles and the particles surrounding the nucleus have a positive charge.

 

So in anti-matter, protons are negative, and electrons are positive, and that's it. Nothing else special about it.

Edited February 19, 2011 by steevey

[Oldman]

To ajb,

Will you please cite some references from published papers?

 

To Steevey,

Please cite some references.

I THINK antimatter is opposite to matter in every charge (the stong, the weak, electro-magnetic, AND gravitational).

If you take an antimatter atom, it has antimatter nucleus and an antimatter electron (positron).

 

To both of you,

I will be be greetful if you cite your or other's research papers. My work depends upon such citations. I have not found any paper that would help me.

 

Thank you

[ajb]

To ajb,

Will you please cite some references from published papers?

 

To both of you,

I will be be greetful if you cite your or other's research papers. My work depends upon such citations. I have not found any paper that would help me.

 

What do you mean by work? If you have something useful to say then you must have hunted through the literature yourself?

 

If the equivalence principle holds then matter and antimatter should interact in the same way. But really this needs to be experimentally tested. You might be interested in the ALPHA project.

 

As for detailed exposition of general relativity and antimatter I suggest you search the arXiv. I am not an expert in this area.

[Oldman]

Thanks ajb. I agree with you -- experiments are needed here.

By work I mean I am developing a new model of gravitation starting over afresh with classical mechanics and electrodynamics. I am tired of all these new theories of grand unification and supersymmetry.

By the way, when I was a graduate student in the late sixties, I remember Prof. Teller giving us a lecture to us students. I asked him about the gravitational force beween matter and antimatter. He said: "Ask me in ten years."

The same question was put forth by George Gamow in the late thirties.

These questions are vital for the principle of equivalence, General Relativity, and my model.

I am not sure about arxiv! But I will look for the ALPHA project. Thanks for pointing it out.

[DrRocket]

Thanks ajb. I agree with you -- experiments are needed here.

By work I mean I am developing a new model of gravitation starting over afresh with classical mechanics and electrodynamics. I am tired of all these new theories of grand unification and supersymmetry.

By the way, when I was a graduate student in the late sixties, I remember Prof. Teller giving us a lecture to us students. I asked him about the gravitational force beween matter and antimatter. He said: "Ask me in ten years."

The same question was put forth by George Gamow in the late thirties.

These questions are vital for the principle of equivalence, General Relativity, and my model.

I am not sure about arxiv! But I will look for the ALPHA project. Thanks for pointing it out.

 

Where does general relativity fit in your picture ?

[alpha2cen]

I have three questions. Your response will greatly help me in my research on gravitation.

 

(1) Do gravitayional masses of matter and antimatter have opposite signs?

 

(2) What's the sign of matter-antimatter gravitational force?

 

 

We have already thought about similar questions. But it is difficult to find absolute evidence. Here are the arguments.

link deleted

Give us a good opinion.

Edited February 20, 2011 by swansont

[swansont]

We have already thought about similar questions. But it is difficult to find absolute evidence. Here are the arguments.

link deleted

Give us a good opinion.

 

!

Moderator Note

Promoting a speculative pet theory in a mainstream thread is against the rules. Stop it.

[Oldman]

Answer to: "Where does general relativity fit in your picture?"

 

General Relativity has passed three classic tests, which we know that. My problem is this:

In GR, the gravitational field is the field of spece-time geometry. Then quantization of this field would be gravitons. And, disturbances in this field would gravitational waves. So far we have found no evidences of either of them despite astronimic collisions and interactions in the universe.

If I missed related papers, would you tell me please?

 

In the words of George Gamow (1961):

"... if a future experiment should show that antiparticles have a negative gravitational mass, it would deliver a painful blow to the entire Einstein theory of gravity by disproving the Principle of Equivalence. ..."

 

He did not explain it fully. I think I understand him, but I can't say it here.

 

A question to the moderator:

Is there a section in the Forum where people may post new ideas fo academic/philosophical discussions? but subject to such declarations?

[ajb]

So far we have found no evidences of either of them despite astronimic collisions and interactions in the universe.

 

The energy scale at which quantum effects of gravity become dominant is far higher than we can hope to probe. So direct evidence of gravitons, or other manifestations of quantum gravity (it may not be a theory of particles, i.e. no gravitons) is unlikely. A possibility is that the imprint of quantum effects could be found in cosmology or by observations of black holes. The early universe and black holes are about the only places that the energy scale is near that of quantum gravity.

 

Direct gravitational wave detection has also turned out to be difficult, but there are lots of experiments trying to detect them. Indirect evidence exists, such as detailed studies of double pulsars. To date, there is no derivation from what is expected by general relativity. This is good and bad. Without some hints from experiment it is not obvious what to theoretically try as a quantum theory of gravity.

[Oldman]

Thanks, ajb.

That's is my understanding as well.

The string theories, as Prof. t' Hooft calls them just a hunch, have no answers either.

Please let me know if you find something new here.

Recently I read a book by Lee Smolin: The Trouble with Physics. Recommend it.

[swansont]

A question to the moderator:

Is there a section in the Forum where people may post new ideas fo academic/philosophical discussions? but subject to such declarations?

 

We have a speculations forum. It has a few additional rules.

[DrRocket]

The energy scale at which quantum effects of gravity become dominant is far higher than we can hope to probe. So direct evidence of gravitons, or other manifestations of quantum gravity (it may not be a theory of particles, i.e. no gravitons) is unlikely. A possibility is that the imprint of quantum effects could be found in cosmology or by observations of black holes. The early universe and black holes are about the only places that the energy scale is near that of quantum gravity.

 

Direct gravitational wave detection has also turned out to be difficult, but there are lots of experiments trying to detect them. Indirect evidence exists, such as detailed studies of double pulsars. To date, there is no derivation from what is expected by general relativity. This is good and bad. Without some hints from experiment it is not obvious what to theoretically try as a quantum theory of gravity.

 

bold added

 

See some details here.

http://www.astro.cornell.edu/academics/courses/astro2201/psr1913.htm

 

So far as I know this is the best empirical evidence for gravitational waves. Direct detection would be better, but this is not bad.

[ajb]

So far as I know this is the best empirical evidence for gravitational waves.

 

Indeed. People at my old University, Manchester have been involved in this area of research.

 

You can find out more here.

[Klaynos]

The last science run of LIGO finished quite recently, we had a colloquium on it a couple of years ago, very very interesting. I believe they are analysing the results currently and that it'll be down for a while whilst they do a big upgrade.

[Oldman]

Thanks for the web reference. I am waiting for the LIGO results as well. I hope it tells us whether the gravitational waves are disturbances in the field of space-tiime geometry or in specific something else.

 

Followup for the Moderator:

I read the Speculative section rules. Under this rule, all String theories and quantum gravity theroy will be out!

Should the evidences be for the premises of a theory or the predictions it makes?

[Mystery111]

I have three questions. Your response will greatly help me in my research on gravitation.

 

(1) Do gravitayional masses of matter and antimatter have opposite signs?

 

(2) What's the sign of matter-antimatter gravitational force?

 

(3) Does General relativity alllow matter and antimatter to warp the field of space-time geometry oppositely?

 

 

 

 

 

1) The mass term for all particles we work with have a positive mass. The appearance of a negative charged particle does not imply changing the positive sign of attraction in the mass term. The Dirac Equation describes particles and antiparticles of fermions. The mass term in that equation does some interesting things...

 

Two specific wave equations, which come to mind are:

 

[math]i\dot{\psi_R} = -i\partial x \psi_R + M\psi_R[/math]

 

[math]i\dot{\psi_L} = i\partial x \psi_L + M\psi_L[/math]

 

both these equations describe right moving waves [math]\psi_R[/math] and left moving wave [math]\psi_L[/math] and they physically represent particles and antiparticles. The mass term is strictly positive, and because of the mass term, it can describe a new type of particle, the majorana particle which is a particle which is it's own antiparticle. The majorana mass term couples left and right movers together. [math]i\dot{\psi}= -i\alpha \partial x \psi + M \beta \psi[/math]

 

2) This question is hard to understand... what is the gravitational sign of the mass terms for matter and antimatter? They will still attract each other, because they have a real mass.

 

3) No

Edited September 21, 2011 by Mystery111

[MigL]

Maybe I'm being too simplistic, But a single photon will, under the right circumstances, create an electron- positron pair, ie matter and antimatter. Now, the original photon has the same gravitational force and sign as an equivalent amount of mass, the electron has the same sign and gravitational force for its mass, so why would the gravitational field change polarity for the positron ?

And why would it flip back again when the electron-positron pair annihilate ?

 

Obviously it doesn't.

The gravitational field is related to the mass and energy of the particle ( more or less ) and this relationship works the same for matter and antimatter.

 

As to rigorous proof and papers which can be quoted, I don't know of any either.

[Mystery111]

In what sense are you using ''polarity''?

[MigL]

+ or - indicating direction.

[Mystery111]

negative and positive what?

 

Are we talking about EM charge, mass-charge? My instincts indicate EM charge, but we've been talking about negative mass signs as well, so I need you to be specific.

 

Let me try this again. Your confusion seems to lye, correct me if I am wrong, in the original state of the antiparticle existing with a negative energy in the vacuum. While it is generally true that particles have negative descriptions before they become real particles existing in the vacuum, implies that the correct equation to represent energy and mass in a Hamiltonian is [math]E= \pm Mc^2[/math]. However, the Mass term does not pick up a negative sign when it becomes a real particle. Recall the equations I showed you concerning the Dirac Equation. The mass term in the equations are identical for those which are particles and antiparticles.

 

What is a mass term? If theory is correct, it is a symmetry-breaking in the equations. To give a particle mass, you must assume some field [math]\phi = \rho e^{i \alpha}[/math]. Explaining this in terms of a mexican hat potential, you can calculate it to the first approximation in respect to [math]f= \rho[/math]:

 

[math]\phi = f e^{i \alpha}[/math]

 

One might know that [math]\phi[/math] is in fact frozen but the alpha field in the exponential is allowed to shift. To calculate the Langrangian, you first need to work out the Covariant Derivative:

 

[math]D\phi = \partial \phi + iA \phi[/math]

 

To compute the action, you must multiply this by it's conjugate:

 

[math] = i(\partial \alpha + A)f e^{i\alpha}[/math]

 

[math] = f^2(\partial \alpha + A)^2[/math]

 

Doing so removes the [math]e^{i\alpha}[/math]. Using a special gauge transformation now, [math]A' \Rightarrow \partial \theta + A[/math]

 

we should notice that in the equation [math] = f^2(\partial \alpha + A)^2[/math] the [math](\partial \alpha + A)[/math] is a gauge transformation where [math]\partial \theta [/math] plays the role of our alpha field. So the final expression is:

 

[math] = f^2A'^2[/math]

 

Notice the alpha field has been absorbed by our object [math]A'[/math], that means no more Goldstone Boson, the Higgs field has provided a mass through shifting the potential from the ground state of origin. This is what a mass is. When this effects a particle like a photon, or any massless boson field it gives that quanta a mass. The mass term might be for an electron-positron pair. And analyzing how the mass term enters the Dirac Equation, permitting a positive mass for an electron and positron tells us that the Higgs field did not induce a negative matter description because there is no evidence for it in the Dirac equation.

 

Here, I should have noted, the [math]f^2[/math] term plays the role of mass.

 

The [math]A[/math] the electromagnetic potential just comes from the equations of electrodynamics. Note that in the electromagnetic equation

 

[math]F_{\mu \nu} = \frac{\partial A_{\mu}}{\partial X^{\nu}} - \frac{\partial A_{\nu}}{\partial X^{\mu}}[/math]

 

where you might see derivates in respect of the [math]A[/math] only, there is no mass term. Also don't ever as a warning mix up the idea of [math]F_{\mu \nu}F^{\mu \nu}[/math] with the [math]f^2[/math] term above. They are different.

Edited September 26, 2011 by Mystery111

[MigL]

No confusion on my part, but maybe a vague answer.

I said + or - indicating direction of the gravitational field. We are discussing wether antimatter's gravity field has any reason to be reversed, are we not ?

What exactly does EM charge have to do with it and ehy would you think I was referring to it ?

Also there is no such thing as negative energy, it is merely a convention for energy conservation 'book-keeping', just like the + or - convention indicating force direction.

[Mystery111]

Then say a positive or negative field. I assumed a charge because all you have me was + and a - .... anyway...

 

...no it does not interchange the sign of the field. Nothing in the equations will determine that.