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Matter-antimatter colision and pure energy

  1. Dec 29, 2008 #1
    sounds like the title of a SF book...and that is what this post will probabley be...
    "if matter and antimatter colide,they anihilate each other and turn into pure energy"
    here comes the questions:
    1)what is pure energy?you can't go at the market to buy a jar of energy,you can't hold energy in your hands...if you kick a ball it will move...that's energy...so as long as you have no more matter or antimatter for the energy to manifest on something,I can't see how you can have energy at all...
    witch brings me to question 2:
    2)let's say I have a star of 1 solar mass made of matter and 1 star of 1 solar mass made from antimatter...if they were to colide,they shoudn't completley turn to energy...the energy obtained by just touching eatch other should be big enough to separate the rest of them at a safe distance(if what I asumed on question 1 is correct)
    I know 1 gram of antimatter would cost 30 or 60 trilion U.S. dollars to produce,so I've chosen the size of stars on purpose,so I make the point very clearley,but now I will aply this pfenomena on much smaller case,in question 3:
    3)if you had antimatter the size of a...let's say a dust particle,you should have quite a hard time,tring to anihilate it with ordinary matter because of this "push" efect I described,so obtaining "pure" energy seems inposible...unless you check
    question 4:
    4)if you colided an elementary particle with an elementary antiparticle in perfect emtiness(if we can talk about pure energy,we can talk about perfect emtiness) nothing should happen...
    also,I've allwais wondered:
    5)does,for example,antihidrogen anihilate with...something else,like iron,or oxigen?or just hidrogen?
    6)what happens if I feed a light bulb with pozitrons instead of electrons? and what hapens if I feed my computer(or any other very advanced electronic system) with pozitrons instead of electrons?
    7)when I used to speak about things in general,I refered to it as matter...but how do you call matter and antimatter and radiations and so on without including the space-time fabric,all togeter? (then it would be easy...you could simpley call it universe)
    note: 1)2)3)and4) aren't exactley questions...they are more like...is it true or not,and why?
    thank you in advance,and please pardon my eventual mistakes,english is not my mother tounge.
    Last edited: Dec 29, 2008
  2. jcsd
  3. Dec 29, 2008 #2


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    Science Advisor
    Homework Helper

    It isn't any purer energy than any other - 'pure energy' just means you only get energy no other residue.

    Practial difficulties aside the two stars would annihilate if you put them together.

    It would be quite easy to completely use it, any bits that were blown away by the initial bang would inevitably hit another bit of matter and go bang.

    Why would the empty surroundings matter?

    It's not a chemical reaction so the protons in hydrogen would annihilate with the anti protons in anti-hydrogen, the electrons with positrons etc
  4. Dec 30, 2008 #3


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    There's no such thing as "pure energy." Energy is a property of a particle or other object. When an electron and a positron (for example) annihilate each other, you get two photons which have a total energy corresponding to the masses plus kinetic energies of the original particles.
  5. Dec 30, 2008 #4
    that is what I suspected,thanks for the confirmation...thanks to all those who posted:)
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