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Realising matter

  1. Oct 14, 2011 #1
    what is the modern definition of matter? is it "all things that occupy space and have mass"? or else?

    is an electron a matter???

  2. jcsd
  3. Oct 14, 2011 #2
    I don't believe there is a hard scientific definition of matter, In loose talk normally it refers to all particles and the stuff they build (atoms, molecules and everything), however I've also heard it described as only the particles that have a nonzero rest mass, so in that case photons would not be matter.

    Edit: QED by Feynman is an example of the latter.
  4. Oct 14, 2011 #3


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    From wikipedia on Matter: Matter is a general term for the substance of which all physical objects consist.[1][2] Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume.[3] However, different fields use the term in different and sometimes incompatible ways; there is no single agreed scientific meaning of the word "matter".

    An electron is almost always considered matter. I've never heard of a situation where it isn't.
  5. Oct 15, 2011 #4
    how can electron be a matter if its not a particle? it behaves like a wave right? how can something with mass just simply vanish and appear at another space.
    correct me if i'm wrong.
  6. Oct 15, 2011 #5


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    ALL elementary particles have quantum mechanical behavior. So why are you concerned only of "electrons"? I can show you neutrons, and entities as large as buckyballs behaving in similar fashions.

    So now, considering that all of us are made up of these things, are you also going to argue that you are not matter either?

    You need to realize that your criteria of what a "matter" must behave has never been used to define what matter is. You are using it as a criteria simply because it is what you expect it to have, as opposed to what is used in physics.

  7. Oct 17, 2011 #6
    so anythinng with rest mass is matter?
  8. Oct 17, 2011 #7
    As Drakkith said, there is not a single definition for matter, but that is one definition.
  9. Oct 17, 2011 #8


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    A particle can exist even if it has zero mass. Photon is an example of such a particle. It is better to view mass just as a property of the particle (like electric charge is property of a particle like electron or proton and color charge is a property for particles like quarks). Also regardless if a particle has non-zero mass or not it can behave as a wave too due to the particle-wave duality principle.
  10. Oct 17, 2011 #9


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    I would say that is correct in the most general sense of the word Matter. Some people prefer to call exotic particles that decay quickly "exotic matter" or not matter at all and consider only the light fermions that compose atoms as matter.
  11. Oct 17, 2011 #10
    Despite what Wikipedia may say about the ambiguity of the word "matter" across fields, from my experience I can relate that within the realm of theoretical physics matter is anything having mass.
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