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Particle/antiparticle annihilation

  1. Sep 16, 2008 #1
    particle/antiparticle "annihilation"

    This has been bugging me for quite some time now.
    Why is it called "annihilation" when a particle and an antiparticle collide, when in fact they don't annihilate at all, but simply transform into photons with the original energy conserved?

    Since "annihilate" literally means "turn into nothing," the two particles (and their energy) would actually have to disappear from existence in order for us to be able to apply this term properly. Are there any plans to do away with this terminology so that this kind of confusion can be avoided? Or am I missing some more specific reason that the word "annihilate" is used?
     
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  3. Sep 16, 2008 #2

    malawi_glenn

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    Re: particle/antiparticle "annihilation"

    Physical and literal meaning of words don't have to coincice. I think annihilation was the first thing that came in mind, also it is seen in the perspective of the particle, it encounters its antiparticle and cease to exist.

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

    I remember I had a similar question earlier this spring. I think there are many terms in physics which might be confusing for the layman.
     
  4. Sep 16, 2008 #3
    Re: particle/antiparticle "annihilation"

    Don't you think there's something wrong with that statement? (besides spelling:wink:)
    Any sort of ambiguity in physical terminology will almost certainly lead to confusion for laypersons wanting to truly learn this stuff. More consistent terminology would make things easier.

    Sure, the particle ceases to exist, but its energy continues to exist in another form. It does not turn into nothing, which is what "annihilate" means.
     
  5. Sep 16, 2008 #4

    malawi_glenn

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    Re: particle/antiparticle "annihilation"

    You have the same problem in religion, theology etc, different branches uses word different. And physics is full of such things. Like charge flowing in opposite direction of electron motion. You have many things from your ordinary life aswell, "the sun is rising" etc.

    So it's no big deal, just get used to it that things get their names from things wich may not be 100% logical correct.

    The goal of physics maybe not is to make it possible for laymen to learn it without learing it proper, if you understand. How can a layman "truly learn" particle-antiparticle interactions without learing quantum physics, quantum field theory etc? Then the layman have surley ceased to exits beeing a layman (the layman have been annihilated by physics textbooks and turned into a physicsist) :-)

    annihilate was used in war terms aswell, when speaking of extintion of races, peoples, tribes etc. So there you have the "problem" again.
     
  6. Sep 16, 2008 #5
    Re: particle/antiparticle "annihilation"

    Its just a word i guess. I mean to laymen, the particles do annihilate and if there is enough, like in Angels and Demons, they annihilate everything around them. Its just a word though. Sounds better than, "When a particle and an antiparticle meet, they come together, transform their mass into pure energy in the form of photons, and the photons go on their own way." Its just easier and also sounds pretty cool!
     
  7. Sep 16, 2008 #6
    Re: particle/antiparticle "annihilation"

    I don't see a problem. You had a particle and an antiparticle, they have collided, and now you don't have either. Seems to me that they have ceased to exist, i.e. annihilated.
     
  8. Sep 16, 2008 #7
    Re: particle/antiparticle "annihilation"

    It's an etymological problem. The word "Nihil" meaning "nothing", literally "annihilation" should mean "reduction to nothing" but of course that violates conservation laws.
     
  9. Sep 16, 2008 #8
    Re: particle/antiparticle "annihilation"

    but your looking way to much into the word. Its just a word. where not trying to break down the word. It describes an action. It has its own definition. Your trying to think to much about the make-up of the word.
     
  10. Sep 16, 2008 #9
    Re: particle/antiparticle "annihilation"

    Etymology is interesting in its own right. It's not because the physical definition was established as such that it was a well chosen word.
     
  11. Sep 16, 2008 #10
    Re: particle/antiparticle "annihilation"

    alright I understand what your saying in the etymology context. It was an badly chosen word but its still a cool word none the less.
     
  12. Sep 17, 2008 #11

    LURCH

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    Re: particle/antiparticle "annihilation"

    Two observations:

    1) As particle and antipartical, the two do cease to exist; their existence as a partical and an antipartical has "become nothing."

    2) Without such qualifiers, we'd have to elliminate the word "anihilate" from our language altogether. Nothing can truly vanish without leaving something behind.
     
  13. Sep 17, 2008 #12

    malawi_glenn

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    Re: particle/antiparticle "annihilation"

    The first observation is wrong, since a photon is created, the electron and positron has not become nothing.

    The second observation is wrong aslo, if we only had word for things which can happen and exists in reality then perhaps we should ger rid of things as "infinity" etc. A word can be useful even though what it resembles don't exist
     
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