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Thread: Fermions and Bosons

  1. #1 Fermions and Bosons 
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    The book I am reading right now says that entities that have an odd number of quarks are fermions and entities with an even number of quarks are bosons. But then it goes off and says sodium 23 is a boson even though it has 69 quarks. It says that you have to add the electrons too, to make 80 which makes it a boson. So how do you determine whether something is a boson or a fermion? because the way they said to do it doesn't always work. Is it actually odd and even charge instead of odd or even amounts of quarks?


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    Fermions have half-integer spin and bosons have integer spin. All quarks and leptons (including electrons) are fermions, thus having a spin of 1/2. So, when you add up a bunch of 1/2s, you get an integer if you have an even number of them and a half-integer if you have an odd number of them. It has nothing to do with charge: it really is a matter of the number of quarks. I don't really see what the problem is... just like the book said (what book is it, by the way?), you have to include electrons, because they are fermions as well as quarks, so their 1/2 spins have to get added into it. Now if you wanted to know if a sodium-23 nucleus was a boson or fermion, obviously it'd be a fermion since it has, like you said, 69 (odd) fermions within it. Does that clear things up at all?


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    The book is called the quantum world. I was getting confused because in the book it kind of acted like the amount of quarks was the way to check if it was a fermion or boson. It mentioned the spins in the book but I didn't make the connection that electrons had an odd half integer too. Thanks for the help.
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    I think I got it now. Is it like this, when we are talking about fermions combining with other fermions only an odd amount of fermions produce a fermion? So an even amount of fermions is a boson. Then when combining bosons with bosons , it doesnt matter whether you have an odd or even amount because you total spin in going to be a whole number?
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    Quote Originally Posted by EV33
    The book is called the quantum world. I was getting confused because in the book it kind of acted like the amount of quarks was the way to check if it was a fermion or boson. It mentioned the spins in the book but I didn't make the connection that electrons had an odd half integer too. Thanks for the help.
    One of the great tragedies of modern physics is the list of names given to particular particles. Confusing to say the least. If only a mathematical map existed to explain the overall mechanical-time-geometry of the subatomic world, a map that was more understandable itself than trying to remember all the exotic names used to label one point different (by their spin, for instance) to another.

    What do you consider is the hardest thing to understand about subatomic-atomic physics?

    For me, it's the lack of certainty of what is being labelled with an exotic term.
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  7. #6  
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    I'd have to agree with you on the most part, some of the terms can be a pretty confusing. I'm pretty knew to all this, I think over time these terms will become much more clear though.
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    What do you think about the idea of having a sub-atomic particle named after you?
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    Quote Originally Posted by EV33
    I think I got it now. Is it like this, when we are talking about fermions combining with other fermions only an odd amount of fermions produce a fermion? So an even amount of fermions is a boson. Then when combining bosons with bosons , it doesnt matter whether you have an odd or even amount because you total spin in going to be a whole number?
    Basically, yeah. Though to my knowledge bosons never really combine. Just remember that fermions have a half-integer spin, and if you multiply 1/2 by anything odd you get something-and-a-half. Something-and-a-half is a half-integer, so it's a fermion.
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    Thanks for the help chemboy. Streamsystems, I think having sub-atomic particles named after people kind of sucks because it doesn't give you any idea of the particles properties, but at the same time how could you turn down the offer. lol
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