Antimatter Definition and 288 Threads

In modern physics, antimatter is defined as matter that is composed of the antiparticles (or "partners") of the corresponding particles of "ordinary" matter. Minuscule numbers of antiparticles are generated daily at particle accelerators—total production has been only a few nanograms (ng)—and in natural processes like cosmic ray collisions and some types of radioactive decay, but only a tiny fraction of these have successfully been bound together in experiments to form anti-atoms. No macroscopic amount of antimatter has ever been assembled due to the extreme cost and difficulty of production and handling.
Theoretically, a particle and its anti-particle (for example, a proton and an antiproton) have the same mass, but opposite electric charge, and other differences in quantum numbers. For example, a proton has positive charge while an antiproton has negative charge.
A collision between any particle and its anti-particle partner leads to their mutual annihilation, giving rise to various proportions of intense photons (gamma rays), neutrinos, and sometimes less-massive particle–antiparticle pairs. The majority of the total energy of annihilation emerges in the form of ionizing radiation. If surrounding matter is present, the energy content of this radiation will be absorbed and converted into other forms of energy, such as heat or light. The amount of energy released is usually proportional to the total mass of the collided matter and antimatter, in accordance with the notable mass–energy equivalence equation, E=mc2.Antimatter particles bind with each other to form antimatter, just as ordinary particles bind to form normal matter. For example, a positron (the antiparticle of the electron) and an antiproton (the antiparticle of the proton) can form an antihydrogen atom. The nuclei of antihelium have been artificially produced, albeit with difficulty, and are the most complex anti-nuclei so far observed. Physical principles indicate that complex antimatter atomic nuclei are possible, as well as anti-atoms corresponding to the known chemical elements.
There is strong evidence that the observable universe is composed almost entirely of ordinary matter, as opposed to an equal mixture of matter and antimatter. This asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics. The process by which this inequality between matter and antimatter particles developed is called baryogenesis.

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  1. E

    What percent of baryonic matter is antimatter?

    What percent of baryonic matter is antimatter? I am well aware that DM accounts for most "matter" and that there was baryon number violation and cp violation to explain the presence of matter over antimatter, but based on theory and observation, what percent of visible matter is predicted or...
  2. K

    How much matter and anti-matter is needed to escape Earth's gravitational force?

    I am having some trouble on the following problem, can someone help me? Any help is greatly appreciated!:smile: 1) A spaceship has a mass of 20000kg. It has a matter-anti-matter engine which can transform the annihilation energy into kinetic energy of the spaceship with an efficiency of...
  3. K

    Solving Matter & Antimatter Problems: Need Help Getting Started?

    I am really stuck on setting up the problem & equations to solve, can someone please help me out with this beginning step? The question is: 1) A plasma out in space containing protons and electrons meets up with another plasma containing anti-protons and positrons. At what rest wavelengths...
  4. belliott4488

    Is the designation as matter vs. antimatter arbitrary?

    Is the designation as "matter" vs. "antimatter" arbitrary? I think this should be a very elementary question, but I haven't seen it addressed anywhere before. (but pardon me if it has been, and I just missed it.) I know that it is arbitrary to designate the electron as a matter particle and...
  5. C

    I have a question about antimatter theory

    I'm not exactly where this belongs (on which board), so feel free to move it if you need to. My question is this: When you combine Deuterium (D) with Tritium (T) in certain situations it causes nuclear fusion to be produced. Now, of course, I realize it isn't that simple, rather there are a...
  6. O

    Why Is There More Matter Than Antimatter in the Universe?

    If there is duality, at the big bang, when matter and antimatter was created, why did the balance shift to matter? Someone told me that there is a theory that the particles that have no charge was left over and created matter?
  7. P

    Beta Decay: Puzzling Creation of Antimatter

    In beta decay, an antibuetrino or an positron is emitted from the nucleus. how is this possible? how can antimatter come directly from matter? This is pizzling...:confused:
  8. L

    How do you create and use antimatter?

    Just how hard is it and how do you create antimatter? I'm thinking if we could use it to start nuclear explosions. How much antimatter does it take to make a fusion reaction occur? Could you use antimatter to create matter? Once a certain amount of antimatter is created could you then use...
  9. A

    Invariant quantities for antimatter

    Since antiparticles have reversed proper time, can I conclude that all invariants are reversed for antiparticles?
  10. F

    When matter and antimatter collide?

    Would I be right in saying that the two are transferred to pure energy?
  11. E

    Matter - Antimatter interactions

    Just curious. I know that antiproton will annihilate with a proton, but is that the only baryon which will react with a proton in such a way. Specifically, do the specific constituent quarks annihilate with their antimatter counterpart or do they only annihilate in the proper 2 and 3 quark...
  12. R

    Clusters of Matter and Antimatter

    Does anyone have opinion on this paper by Dr. Mishustin on theoretical possibility of coexistence of matter and antimatter? : http://www.fias.uni-frankfurt.de/symposium/papers/mishustin.pdf Is such research being conducted elsewhere ?
  13. V

    Suggestion on antimatter coursework

    i am now doing a (alevel) coursework on antimatter, can someone pls suggest some topics to include :rolleyes: ths
  14. M

    What made the scientists to think about Antimatter

    I just want to know what made the scientists to think about Antimatter... And what's the use of it?
  15. T

    The Secrets of Antimatter and Fast Propelling Technology

    Hey I don't know if this in the right category but i'll ask it anyway. I was watching TV when some documentary came on, it was on some particles called antimatter(refered as antiphotons,antineutrons,etc)and the person said if you bash a bunch of photons at the speed of light at some type of...
  16. F

    Research about matter - antimatter reactor

    I looking for research about matter - antimatter reactor; any information is good. Thank you.
  17. L

    Confused about this antimatter stuff

    i'm getting quite confused about this antimatter stuff. I've heard that for every particle there is a corresponding antiparticle somewhere out there in the universe. but it also said somewhere else about the big bang theory, that the universe only exists because for some unexplained reason there...
  18. B

    If antimatter and matter become pure energy when they combine and an

    If antimatter and matter become pure energy when they combine and an electron has an antiparticle (a positron) what is the energy that comes from their combination? I thought electrons were made of energy. Thanks
  19. G

    How does antimatter relate to chemistry?

    Could you guys please give me examples of how antimatter relates to chemistry? thanks :)
  20. G

    Are there any antimatter calculations?

    Are there any antimatter calculations, that are in any way related to antimatter? (Please post the equation and the use of it :)) Also, I already am aware of the E = mc^2 one ;)
  21. V

    Has CERN Confirmed the Existence of Antimatter?

    Humble apologies if a thread regarding this has already been started. I was just browsing through the net and got to read about antimatter.It is already proven by CERN that it is not a rumour but truth that it does exist and CERN is producing it in minimal amounts.It is something which I...
  22. I

    Unveiling the Mystery of Antimatter in the Universe

    I'm told that most of the observable universe is made up of "normal" matter. How did physicists come to this conclusion? There is no difference between matter and antimatter when observed.
  23. z-component

    Antimatter in Space: How Could It Exist?

    I've read that in 1977, scientists approximated that there is a deposit of antimatter in the center of our galaxy. How could antimatter exist freely in space while coming into contact with matter? I know that once antimatter and matter come into contact, they are destroyed immediately while...
  24. G

    Matter and antimatter must interchangible

    If I have 1 KG of matter, and 1 KG of antimatter, and I combine the 2, then I get 2c^2 = 1.79751036 × 10^17 joules, then in turn, I convert the 1.79751036 × 10^17 joules back to 2 KG of mass. So, if antimatter is so anti, why can they be converted? :rolleyes:
  25. C

    Energy required to accelerate a ship WITH ANTIMATTER

    Energy required to accelerate a ship.. WITH ANTIMATTER! Hey, I was reading a science fiction book that had lots of fast pitched space battles, ships manoeuvring around at 8 gees and stuff, powered by antimatter :P . So I was wondering, let's say you had a ship with a mass of 1000 tonnes.. how...
  26. Simfish

    Antimatter - could it ever be utilized as poss. energy source?

    I'm guessing that the amount of energy taken to generate an antimatter particle would always be more than what you would get back by colliding the antimatter generated with a matter particle. But if we ever find a source of antimatter in the universe, then do you suppose that in the far...
  27. R

    What is Antimatter and How Does it Work?

    I have always been interested in Antimatter. Wherever I go to find information I never get a definite answer. Please end my search. I'll be happy even with the most dry facts. Thanks, RP
  28. I

    What are the forces applying to antimatter?

    I don't know if this is true or not, and I have a feeling that it has already been proven otherwise, but I think that the forces applying to antimatter are flipped. For instance, a positron and an electron would repel, and a positron and a proton would attract(don't mind the inserting of the...
  29. K

    Dark energy + missing antimatter

    dark energy + "missing" antimatter Did dark energy stop antimatter from being produced in the early universe and is this why there is not much antimatter around today?
  30. G

    Why Does Antimatter Annihilate Matter?

    is there any particular reason that antimatter will annhilate matter? This question has been bothering me for a while... thanx
  31. Antonio Lao

    Antimatter and Antigravity Connected ?

    Antimatter and Antigravity Connected ? The matter in our universe is controlled by gravity which is a long range force obeying the inverse square law. In the large, antimatter cannot be found by astrophysicists and cosmologists. So the assertation that the universe is dominated by matter only...
  32. Antonio Lao

    Antimatter as Vehicle in Time Travel

    What would be the state of a universe that contains only antimatter? Is it in a state of contraction or expansion similar to ours? As what Feynman diagram shows antiparticles travel backward in time, so if we can transform ordinary matter into antimatter by changing the protons to...
  33. N

    Questions about Antimatter: Gravity, Singularity, Entropy, Black Holes & C-22

    I just hava a few questions about antimatter. Does it have gravity? Can you compress it into a singularity?, and if so what would happen if you were pulled towards it? Does it have entropy? Could you use it to destroy black holes? An isotope of carbon(C-22?) decays and produces antimatter...
  34. P

    Basics of neutrinos are they antimatter particles

    Hi guys just had a question. I know about neutrinos and how they act - their being able to pass through matter leaving it as it was but my question was how are what are the basics of neutrinos are they antimatter particles of some particle? Someone please enlighten me, thanks.
  35. I

    Fuel of the future is antimatter

    Recently read in an article that the fuel of the future was antimatter... My question is how would they contain antimatter to get it to react with only the matter that they wanted it to react with. You wouldn't be able to put it in a container, wouldn't it collide with the matter and completely...
  36. A

    Greetings and antimatter question

    Greetings everyone, I'm new to these forums and would first like to salute all of you. Also, I've got a few little questions about matter/antimatter interaction and was wandering if anybody could help me out. What are the conditions that must be met for a particle and an antiparticle to...
  37. M

    Is the Missing Antimatter of the Universe Just a Matter of Labeling?

    A colleague has posted an essay on antimatter at [PLAIN]www.rfprobes.com.au/gimliphysics/symm.htm[/URL] . It is suggested that the missing antimatter of the universe is not missing at all. In other words there is no baryonic asymmetry and CP violation has been misinterpreted. I think the ideas...
  38. G

    200,000 years for 1mg of antimatter?

    Ok, I've just been reading this http://www.cem.msu.edu/%7Ecem181fp/antimatter/antimatter.html and it says that even if Fermilabs increases its production of antimatter to 5 times its current output then it would still take another 200,000 years to get 1 miligram of that stuff... I know this...
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