Antimatter

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Toastmaster

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I've heard alot about antimatter but I still don't understand what it is, how its "made" and whether its even real or just a theory. If someone could clarify I would be very gratful for your help.
 
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DrRocket

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Toastmaster":ugc8iqrz said:
I've heard alot about antimatter but I still don't understand what it is, how its "made" and whether its even real or just a theory. If someone could clarify I would be very gratful for your help.
Every particle has an antiparticle counterpart. The counterpart to an electron is positron and the counterpart to a proton is an anti-proton. The photon is its own antiparticle.

The existence of the positron was predicted by Dirac. The existence of the other antiparticles is part of the Standard Model of particle physics. Antiparticles have been and are being produced in particle accelerators and their existence is quite real.

But there are not a lot of them. The overwhelming quantity of matter in the universe is, so far was we know, ordinary matter.

http://en.wikipedia.org/wiki/Antiparticle
 
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emudude

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Important to note as well is that your sub-atomic particles (proton, neutron, electron) are composed of sub-sub-atomic particles called "quarks", and that "antimatter" is just the opposite combination of quarks that a proton, neutron, or electron would have. For all we know, quarks could be made up of smaller sub-atomic particles, and those particles be made up of even smaller particles, and who knows where it could end. Basically what I'm saying is that matter and antimatter are only two different sets of combinations of particles out of a potentially infinite set. :p
 
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DrRocket

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emudude":1ivqmogs said:
Important to note as well is that your sub-atomic particles (proton, neutron, electron) are composed of sub-sub-atomic particles called "quarks", and that "antimatter" is just the opposite combination of quarks that a proton, neutron, or electron would have. For all we know, quarks could be made up of smaller sub-atomic particles, and those particles be made up of even smaller particles, and who knows where it could end. Basically what I'm saying is that matter and antimatter are only two different sets of combinations of particles out of a potentially infinite set. :p
Electrons are true elementary particles. So far as is known they are not composed of quarks or anything else. The positron is also elementary. No quarks there either.
 
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DrRocket

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DrRocket":3qvki633 said:
emudude":3qvki633 said:
Important to note as well is that your sub-atomic particles (proton, neutron, electron) are composed of sub-sub-atomic particles called "quarks", and that "antimatter" is just the opposite combination of quarks that a proton, neutron, or electron would have. For all we know, quarks could be made up of smaller sub-atomic particles, and those particles be made up of even smaller particles, and who knows where it could end. Basically what I'm saying is that matter and antimatter are only two different sets of combinations of particles out of a potentially infinite set. :p
Electrons are true elementary particles. So far as is known they are not composed of quarks or anything else. The positron is also elementary. No quarks there either. Anti-particles exist for all particles whether they are composed of quarks or not. And many particles are not composed of quarks. Neutrinos for instance.
 
K

kg

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DrRocket":1qku1ht8 said:
Electrons are true elementary particles. So far as is known they are not composed of quarks or anything else. The positron is also elementary. No quarks there either. Anti-particles exist for all particles whether they are composed of quarks or not. And many particles are not composed of quarks. Neutrinos for instance.
How is it that a photon is it's own anti-photon? I've heard this before but I have absolutley no idea what is ment by this.
 
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DrRocket

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kg":3cxzlq0t said:
DrRocket":3cxzlq0t said:
Electrons are true elementary particles. So far as is known they are not composed of quarks or anything else. The positron is also elementary. No quarks there either. Anti-particles exist for all particles whether they are composed of quarks or not. And many particles are not composed of quarks. Neutrinos for instance.
How is it that a photon is it's own anti-photon? I've heard this before but I have absolutley no idea what is ment by this.
http://www2.slac.stanford.edu/vvc/theor ... uarks.html
 
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kelvinzero

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Hey can anyone confirm or correct these concepts I think I heard somewhere once, but havent found a reference for:

(a) that a positron is equivalent to an electron travelling backwards in time,

(b) that an electron-positron annihilation (to form two photons) is equivalent to an electron simply being deflected by a photon, just rotated such that time and space axes are swapped.

http://en.wikipedia.org/wiki/Feynman_diagram
 
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MeteorWayne

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kelvinzero":1qxkfgl0 said:
Hey can anyone confirm or correct these concepts I think I heard somewhere once, but havent found a reference for:

(a) that a positron is equivalent to an electron travelling backwards in time,

(b) that an electron-positron annihilation (to form two photons) is equivalent to an electron simply being deflected by a photon, just rotated such that time and space axes are swapped.

http://en.wikipedia.org/wiki/Feynman_diagram
No a positron is an equivalent electron with a positive charge.

No, an electron-positron anihilation is eqivalent to the mass of the two particles being converted to energy, and two photons of 511 kev is the most likely (though not the only) way that energy is released.
 
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kelvinzero

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MeteorWayne":31et8nbo said:
No a positron is an equivalent electron with a positive charge.

No, an electron-positron anihilation is eqivalent to the mass of the two particles being converted to energy, and two photons of 511 kev is the most likely (though not the only) way that energy is released.
Yes, yes, I know all that. :)

Ah.. going to have a look for a reference for the first, I found a reference for the second also:

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

Feynman also employed retrocausality to propose a model of the positron[18] by reinterpreting the negative-energy solutions of the Dirac equation. In this model, electrons moving backward in time would appear to possess 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.[19] 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."[20] Although further understanding of antimatter has rendered this model largely obsolete,[21] it is still employed for conceptual purposes, such as in Feynman diagrams.
 
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JeffreyNYA

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DrRocket":2f8inqgo said:
Toastmaster":2f8inqgo said:
I've heard alot about antimatter but I still don't understand what it is, how its "made" and whether its even real or just a theory. If someone could clarify I would be very gratful for your help.
Every particle has an antiparticle counterpart. The counterpart to an electron is positron and the counterpart to a proton is an anti-proton. The photon is its own antiparticle.

The existence of the positron was predicted by Dirac. The existence of the other antiparticles is part of the Standard Model of particle physics. Antiparticles have been and are being produced in particle accelerators and their existence is quite real.

But there are not a lot of them. The overwhelming quantity of matter in the universe is, so far was we know, ordinary matter.
What is confusing about this whole thing is that if there is an anti-particle for each particle then where are they? I am assuming that anti-particle act like regular ones and repel each other, so they would not all be clumped together somewhere. But if they were really out there in the same proportion as their counterparts then there would be many issues with anything existing correct?

FYI: I know very little about this, just trying to get a little more educated.
 
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Saiph

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Where are they indeed....and that is a major question in cosmology that we have barely and clue on how to begin answering.

If anybody figures it out, we'll be sure to tell you :)


Amazing what simple questions we dont' have answers for isn't it?
 
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ihwip

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DrRocket":26nryf4t said:
Toastmaster":26nryf4t said:
I've heard alot about antimatter but I still don't understand what it is, how its "made" and whether its even real or just a theory. If someone could clarify I would be very gratful for your help.
Every particle has an antiparticle counterpart. The counterpart to an electron is positron and the counterpart to a proton is an anti-proton. The photon is its own antiparticle.

The existence of the positron was predicted by Dirac. The existence of the other antiparticles is part of the Standard Model of particle physics. Antiparticles have been and are being produced in particle accelerators and their existence is quite real.

But there are not a lot of them. The overwhelming quantity of matter in the universe is, so far was we know, ordinary matter.

http://en.wikipedia.org/wiki/Antiparticle
One question I have is regarding bosons. Do they have anti-particles or are they also their own anti-particles?
 
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Saiph

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the answer is: both. Bosons are particles with integer spin. This can range from atomic nuclei (depinding on proton/neutron ratios) to photons. Photons are their own anti-particle, atomic nuclei are not. There's a few other boson's out there too, that I'm a bit unsure about (higgs for instance).
 
K

kg

Guest
Saiph":4xu2d20q said:
the answer is: both. Bosons are particles with integer spin. This can range from atomic nuclei (depinding on proton/neutron ratios) to photons. Photons are their own anti-particle, atomic nuclei are not. There's a few other boson's out there too, that I'm a bit unsure about (higgs for instance).
I asked a similar question in this very same topic. Dr. Rocket posted this link as a reply and I copied this helpful quote below it.

http://www2.slac.stanford.edu/vvc/theor ... uarks.html
For charge zero mesons with the same type of quark and antiquark, and for the charge zero force carriers (photon and Z), the particle and the antiparticle are identical. The antiparticle of a photon is a photon, likewise the antiparticle of a phi meson (s quark and anti-s quark) is a phi meson.

Gluons are force carriers with zero electric charge, but each type of gluon has a color charge. Thus each gluon has a corresponding antiparticle with a related color charge.
 
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