Matter, Anti Matter, and Dark Matter

[Basi]

Matter is obviously straight forward. I have my ideas on anti matter and dark matter but an not completely sure. Space has always been a fascinating topic for me so can someone enlightened on this topic provide some information?

 

 

appreciate it

[imatfaal]

spyman put together a nice post with brief entries on dark matter, dark energy and anti-matter with links to more info

 

it's here http://www.scienceforums.net/topic/56901-dark-matter-anti-matter/ at post 10

[Basi]

spyman put together a nice post with brief entries on dark matter, dark energy and anti-matter with links to more info

 

it's here http://www.sciencefo...er-anti-matter/ at post 10

 

yeah i've read that wikipedia page quite a few times but it doesn't really tell me anything i don't already know. too many vague terms. has there been any respectable articles of such posted?

[imatfaal]

If you need references there are 88 at the bottom of the dark matter pages alone. If those pages are too simple you are going to be more specific on your question.

[BJC]

If you need references there are 88 at the bottom of the dark matter pages alone. If those pages are too simple you are going to be more specific on your question.

The "spyman post" implies that only charged particles can have anti-particles which is not true. An antiphoton is said to be the same particle as a photon. Could a more accurate statement be we cannot distinguish between a photon,anti-photon, or a more general we cannot distinguish between a boson, anti-boson?

 

Do all particle, anti-particle interactions result in annihilation?

What happens in a (graviton, anti-graviton) interaction?

Does a high energy gamma ray continually change to electron, positron pairs, then back again? Could this be the reason for gamma ray delay? ( Gamma Ray Delay May Be Sign of 'New Physics' )

 

Dark energy:

Are there any observations which would indicate that dark energy is something other than vacuum energy? (I know there are theoretical arguments.)

 

I often read that dark energy is a "counter force" to gravity but this description implies that a dark energy quanta has similar quantum characteristics as a graviton. Does a dark energy quanta exist? Is there such a thing a a quanta of vacuum energy? What is the implication in general relativity of anti-gravitons, anti-dark energy?

[timo]

The "spyman post" implies that only charged particles can have anti-particles which is not true. An antiphoton is said to be the same particle as a photon. Could a more accurate statement be we cannot distinguish between a photon,anti-photon, or a more general we cannot distinguish between a boson, anti-boson?

Nope. The pair of charged W bosons is perhaps the most prominent example against your idea.

 

Do all particle, anti-particle interactions result in annihilation?

Apart from the semantic problem what you mean by annihilation (would the reaction of electron+postion to muon+anti-muon be an "annihilation"? If so, why would about electron+electron to muon+muon be not?): No. For instance, the reaction electron+positron to 2electron + 2positron is possible.

 

What happens in a (graviton, anti-graviton) interaction?

Considering that gravitons have the tendency to interact preciously little with anything (compared to other particle physics effects), I'd bet on "preciously little" squared

 

Are there any observations which would indicate that dark energy is something other than vacuum energy? (I know there are theoretical arguments.)

There is an addend that appears in the equations for the gravitational field, which is usually considered to be non-zero. If you insist on interpreting this term as a physical object rather than just an addend in the equation, then it can be considered as some unknown physical object contributing to the energy-stress-momentum tensor. I am not aware of any reason to do so, other than that an addend which has no physical interpretation in a physical equation is a bit weird. Hence, this addend is given a generic name (and since you want your scientific publication to be cited, you give it a catchy name that catches the readers' interest: dark energy ). The problem is, if I remember that correctly, that the pressure contribution of your "physical object of unknown composition" to the total pressure is negative, which is somewhat weird. I am not sure if vacuum energy, whatever that may be in detail, contributes negative pressure.

 

I often read that dark energy is a "counter force" to gravity but this description implies that a dark energy quanta has similar quantum characteristics as a graviton.

It doesn't. The electromagnetic force is usually considered to be the cause that I do not fall through the floor. So it is a counter force to gravity, too. That doesn't say that the photon has similar "quantum characteristic" (again: slightly depends on whatever "quantum characteristics" may actually be in detail) as the graviton - or does it?

Edited May 28, 2011 by timo

[BJC]

Nope. The pair of charged W bosons is perhaps the most prominent example against your idea.

True. I was referring mainly to detecting uncharged particles such as gluons, Z bosons, . For instance this reaction:

 

[latex]e^- + e^+ -> \gamma + \gamma[/latex]

 

the two photons are required for energy & momentum conservation. Could the 2 photons be a photon and anti-photon but we lack the methods to detect the difference?

I became curious about this when hearing about how a phase rotation of 2pi can be detected and differentiated from a phase rotation of 4pi (Aharonov - Susskind effect).

 

 

 

dark energy:

I know that the cosmological constant and vacuum energy are the same thing. And a "time varying but space constant" dark energy field is consistent with the vacuum energy field.

 

However there still is a "search for dark energy" and hence my question "Are there any observations which would indicate that dark energy is something other than vacuum energy?"

Edited May 28, 2011 by BJC