The Antiphoton

[Severian]

The Idea of anti-matter is reliant on the concept of matter, i.e matter and particles thereof are massive; they have mass.

As I understand it, a photon is mass-less, therefore the idea of an anti-photon is unintelegable.

 

No - it has nothing to do with mass. You can have massive particles which are their own antiparticle, no problem.

[BenTheMan]

Most photons have spin 1, btw.

 

Most?

[timo]

"Most" is absolutely sufficient to say that the spin-zeroness of the photons is not the reason that there is no anti-photon. "There are photons with spin 1" would have been the better wording, perhaps.

 

As it's already been said, the post I was referring to has been edited afterwards, hence the statement is a bit out of context.

[pioneer]

If you had anti-hydrogen with a negative proton and positive electron, the interaction is still EM, so the photons will still be based on the EM force. If looked at only energy emission, you would not be able to tell the difference between a hydrogen and anti-hydrogen cloud or star. If it came down to phase difference, this can be simulated with a slight time delay making it inconclusive.

[dirtyamerica]

Electrons are distinguishable from their antiparticles, since they are charged.

 

aka positrons

[AlphaNumeric]

Electrons are distinguishable from their antiparticles, since they are charged.

Bingo. Antimatter has the opposite charges, under the three quantum forces, that normal matter does. So if you can find a particle which has zero charge under the three quantum forces then you have an example of a particle whose antimatter version is itself. Examples are the photon, the Z boson and, on theoretical grounds, the graviton. All other particles are charged under at least one of the forces.

[swansont]

Bingo. Antimatter has the opposite charges, under the three quantum forces, that normal matter does. So if you can find a particle which has zero charge under the three quantum forces then you have an example of a particle whose antimatter version is itself. Examples are the photon, the Z boson and, on theoretical grounds, the graviton. All other particles are charged under at least one of the forces.

 

The ^{[math]\pi^0[/math]} is also its own antiparticle

[Severian]

Bingo. Antimatter has the opposite charges, under the three quantum forces, that normal matter does. So if you can find a particle which has zero charge under the three quantum forces then you have an example of a particle whose antimatter version is itself. Examples are the photon, the Z boson and, on theoretical grounds, the graviton. All other particles are charged under at least one of the forces.

 

That is not necessarily true. Theoretically it is quite easy to construct a particle which is its own antiparticle. For a boson, that is just making the field real, so under complex conjugation it maps onto itself. For a fermion, it is a case of making the lower two entries of the Dirac spinor (in the Dirac representation) the conjugate of the upper two.

 

Indeed, the jury is still out on whether the neutrino i a Dirac or Majorana particle. If it turns out to be Majorana, then it is its own antiparticle. Also, if minimal supersymmetry turns out to be true, then the neutralino would be its own antiparticle despite having weak interactions.

[BenTheMan]

Indeed, the jury is still out on whether the neutrino i a Dirac or Majorana particle.

 

What is your opinion on this, Sverian?

[Klaynos]

I might be miss-remembering something but don't the neutrino detectors detect antineutrinos and neutrinos differently?

[AlphaNumeric]

The ^{[math]\pi^0[/math]} is also its own antiparticle

I was going for elementary particles only (or what we currently think are elementary). There's tons of bound states of matter and it's antimatter versions, some we call particular particles, others are a little more open to opinion like positronium, the bound state of an electron and a positron. Unstable obviously.

For a fermion, it is a case of making the lower two entries of the Dirac spinor (in the Dirac representation) the conjugate of the upper two.

Fair point. I'm familiar with Weyl/Dirac representations etc but I've never used them in regards to the neutrino, only within SUSY string constructions and that's a little departed from considering the phenomenology of the particles.

[Severian]

What is your opinion on this, Sverian?

 

In my (prejudiced) opinion, I think they will be Majorana.

 

It seems clear by now that there should be a right-handed neutrino state if the SM is going to make any sense.

 

For a Dirac neutrino, that state is just like the left-handed one except it has no electroweak interaction, and its coupling to the left handed electron (that is, its mass) must be very small.

 

But if we are going to have a right-handed neutrino, then it must be neutral to all forces except gravity. It has no charge, no isospin and no color. That means that there is no symmetry to protect its mass from quantum effects and its mass should naturally be at the scale of gravity. So it needs to be very very heavy.

 

If this is the case, then the "see-saw" mechanism comes into play. The pre-see-saw left-handed neutrino could naturally have a mass similar to the other leptons, but then mixing with the heavy right-handed state pushes this down to very small masses we see and make it a Majorana particle.

 

I might be miss-remembering something but don't the neutrino detectors detect antineutrinos and neutrinos differently?

 

Sort of. You have to define how you are going to recognise an antineutrino, and in the things you have read, they are probably recognising them by their interactions.

[BenTheMan]

In my (prejudiced) opinion, I think they will be Majorana.

 

I agree. I've never really met anyone who votes for Dirac neutrinos, except possibly Paul Langacker.

[Pete]

I'm not a particle physisist, but I think I see the answer.

 

The Idea of anti-matter is reliant on the concept of matter, i.e matter and particles thereof are massive; they have mass.

As I understand it, a photon is mass-less, therefore the idea of an anti-photon is unintelegable.

I don't see why that would be true. When it was thought that the proper mass of a neutrino was zero it was still known that anti-neutrinos existed. A particle can have an antiparticle even when its proper mass is zero.

[cserez]

Is there any evidence for the existence of an antiphoton? Or an antimatter version of any of the other force-carrier particles?

 

The followings are merely wild ideas and speculations, so don’t take it too seriously

 

What if there exists a particle which is quite similar like photon but it travels backward in time with constant speed? Let’s call it backton.

Now, something must happen when a backton meets a conventional particle.

In the level of elementary particles the quantum mechanics rules the world.

What if the backtons are responsible for collapsing the wave function?

If one accepts the many-world interpretation of quantum theory, then maybe backton plays role in splitting the world-lines.

The observer plays key role in the quantum theory.

What if consciousness itself is somehow related to backtons?

What if the light-speed limit in relativity theory is also related somehow to the backton-flow present everywhere?

What if the backton-theory is the missing link between quantum mechanics and relativity?

[toastywombel]

The followings are merely wild ideas and speculations, so don’t take it too seriously

 

What if there exists a particle which is quite similar like photon but it travels backward in time with constant speed? Let’s call it backton.

Now, something must happen when a backton meets a conventional particle.

In the level of elementary particles the quantum mechanics rules the world.

What if the backtons are responsible for collapsing the wave function?

If one accepts the many-world interpretation of quantum theory, then maybe backton plays role in splitting the world-lines.

The observer plays key role in the quantum theory.

What if consciousness itself is somehow related to backtons?

What if the light-speed limit in relativity theory is also related somehow to the backton-flow present everywhere?

What if the backton-theory is the missing link between quantum mechanics and relativity?

 

There is already a theoretical particle that is suspected to travel back in time, its called a tachyon. Check it out http://en.wikipedia.org/wiki/Tachyon

[Severian]

I agree. I've never really met anyone who votes for Dirac neutrinos, except possibly Paul Langacker.

 

Paul is a smart guy, so his vote counts for a lot of the alternate votes.

[Phx Lord]

Firstly, you use the word tachyon to describe backward in time particles.

All antimatter moves backward in time.

You have just used one word to identify different antimatter particles that will react differently. Take care to be more specific in the future.

 

Secondly, I belive these backtons (good name) must take energy from the present to account for its backward travelling nature.

It may also be possible to to use backtons to incite a flow of positrons, similar to a solar panel effect.

 

Thirdly, the wave-antiparticle duality of it would cause backton waves to propagate towards its origin, no?

 

Fourthly, don't you think Chronons sound so much cooler??

[toastywombel]

Firstly, you use the word tachyon to describe backward in time particles.

All antimatter moves backward in time.

You have just used one word to identify different antimatter particles that will react differently. Take care to be more specific in the future.

 

Secondly, I belive these backtons (good name) must take energy from the present to account for its backward travelling nature.

It may also be possible to to use backtons to incite a flow of positrons, similar to a solar panel effect.

 

Thirdly, the wave-antiparticle duality of it would cause backton waves to propagate towards its origin, no?

 

Fourthly, don't you think Chronons sound so much cooler??

 

Antimatter does not move backward in time.

[swansont]

If you do time-reversal, then you reverse charge+parity to preserve CPT symmetry. Antiparticles look like particles moving backward in time, and are depicted that way in Feynman diagrams.

 

Going from that to "backtons" is a huge leap without the benefit of any physics to support it.

[Severian]

Antiparticles look like particles moving backward in time, and are depicted that way in Feynman diagrams.

 

More properly, anti-particles look like negative energy particle states propagating backwards in time. This is known as the Feynman-Stueckelberg Interpretation.

[sr.vinay]

Okay, consider a wave explanation for the anti-particle. It's said that crests and troughs cancel each other out.

Is it possible for troughs or crests to perfectly cancel each other out? If not, when they do so imperfectly, what happens to the remaining part?

If it's more anti-particle, it remains so?

[Phx Lord]

Antimatter does travel back in time.

I use the wave model of wave-antiparticle duality to describe this as EM wave mechanics are simple.

Antimatter travels back in time towards its source as the wave propagates backwards also. and then i lost my thought pattern.

 

The reason that antimatter will cancel matter is because the antimatter's backwards in time energy, shown as -E (like a vector), causes a mass deficiency such that: -E=(-m)c^2

This eliminates the mass of matter, creating nothing.

 

I guess that this would cause matter to have no mass, as mentioned, but also to be travelling in both directions of time with equal energy.

Have a think on the consequences of this.

Edited April 21, 2010 by Phx Lord

[Klaynos]

We know that antimatter has positive mass.

 

And it doesn't travel backwards in time.

[Phx Lord]

This is just my theory. If you could explain how you know antimatter has positive mass, I would like to hear it.

 

And regardless, I have not said when antimatter has negative mass. This is so only in relation to the present, as the mass of antimatter does not follow a linear timeline with us and so with something like a mass/time graph the mass would decrease and is therefore negative.