Do anti-stars emit or absorb photons?

[Nasher]

Do antistars absorb photons?

I read Feynman's Book, "QED - The Strange Theory of Light and Matter", there a while back.

With reference to Feynman's book, "QED",

The backwards-moving electron when viewed with time moving forwards appears the same as an ordinary electron, except it's attracted to normal electrons - we say it has a "positive charge." (Had I included the effects of polarization, it would be apparent why the sign of j for the backwards-moving electron appears reversed, making the charge appear positive.) For this reason it's called a "positron." The positron is a sister particle to the electron, and is an example of an "anti-particle."

This phenomenon is general. Every particle in Nature has an amplitude to move backwards in time, and therefore has an anti-particle. When a particle and its anti-particles collide, they annihilate each other and form other paricles. (For positrons and electrons annihilating, it is usually a photon or two.) And what about photons? Photons look exactly the same in all respects when they travel backwards in time - as we saw earlier - so they are their own anti-particles.

He said,... "Every particle in Nature has an amplitude to move backwards in time, and therefore has an anti-particle."
So, from this I think an anti-photon would look like a photon, but a photon is traveling forward in time, whereas an anti-photon is like a photon traveling backwards in time.

Just wondering, althought an antistar may not exist.
And the CP violation sure does seem to put a spanner in the works for time reversal symmetry...

If an anti-star did exist, would it be emitting anti-photons.
As far as I know, an anti-photon is like a photon going backwards in time.
Therefore, I reckon, from our perspective the anti-matter star, would seem to be absorbing photons.

If this is so then an anti-star would be a bit similar to a black hole in the sense that they are not directly visible.
However a black hole is different as it is the result of the collapse of regular matter due to its gravity.

What do you's reckon? When viewed with time moving forward as we experience it, would the antistar seem be absorbing photons?

I haven't a clue is there any known anti-matter star, or if such a thing as an anti-supernova has ever occurred (like a supernova happening backwards in time). Probably unlikely because of the CP violation.

 

[smallphi]

The Feynman statement that antiparticles can be viewed as particles is just an expression of certain mathematical analogy. You can either view antiparticles as antiparticles moving forward in time or as particles moving backwards in time.

A star made of antimatter will emmit antiparticles, in particullar antiphotons. Since antiphotons are the same particles as photons, the antistar will emmit photons in the usual way.

 

[Wallace]

Photons do not travel in time. It sounds strange but that is what relativity tells us. As a rough handwaving explanation, you may have heard that as your relative velocity increases the rate at which time 'ticks' on your watch compared to the stationary reference observer decreases. The closer you get to the speed of light (relative to the other observer) the slower it gets by comparison. For light which, obviously, travels at the speed of light this rate goes to zero. Time does not 'tick' at all. So photons don't 'experience' time 'ticking' and hence they don't have a time reversed anti-particle.

For an explanations of why we don't expect to find anti-stars see https://www.physicsforums.com/showthread.php?t=172131"

 

[Chronos]

No anti-stars, nor anti-photons. They do not exist in this universe. An anti-photon is paradoxical to begin with. Think zero spin.

 

[Nasher]

Retrocausality

This is a quote from this interesting link about Retrocausality...

http://en.wikipedia.org/wiki/Retrocausality

Feynman also employed retrocausality to provide a proposed model of the positron[16] by reinterpreting the negative-energy solutions of the Dirac equation. In this model, electrons moving backward in time would appear to possesses a positive electric charge. Wheeler invoked this concept to explain the identical properties shared by all electrons, suggesting that "they are all the same electron" with a complex, self-intersecting worldline.[17] Yoichiro Nambu later applied it to all production and annihilation of particle-antiparticle pairs, stating that "the eventual creation and annihilation of pairs that may occur now and then is no creation or annihilation, but only a change of direction of moving particles, from past to future, or from future to past."[18] Although further understanding of antimatter has rendered this model largely obsolete,[19] it is still employed for conceptual purposes, such as in Feynman diagrams.

It said that Feynman employed retrocausality to provide a proposed model of the positron, electrons moving backward in time would appear to possesses a positive electric charge.

And then goes on to say, further understanding of antimatter has rendered this model largely obsolete.

This suggests antistars are not stars going backwards in time from our perspective.



Any suggestions to what the largest anti-matter object would be?

Would it be just anti-particles, or would it be anti-hydrogen, or larger anti-atoms, or multiple anti-atom object, or anti-one_kilogram object, or anti-planet,
or antistar, or anti-galaxy, or anti-cluster, or anti-universe?

 

[Wallace]

This suggests antistars do not absorb photon from our perspective.

No it doesn't. Anti-matter things such as stars or gas clouds would interact with light exactly as the equivalent matter objects would. They would be indistinguishable from a distance.

 

[Nasher]

No it doesn't. Anti-matter things such as stars or gas clouds would interact with light exactly as the equivalent matter objects would. They would be indistinguishable from a distance.

I meant...

This suggests antistars are not stars going backwards in time from our perspective.