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Are all elementary particles point particles?

  1. Jul 18, 2013 #1
    That's my first question.

    2. If that's true, why do they have different masses?

    3.Since everything is made of point particles, do the fundamental forces give the actual "size" to the particles?

    4.Lastly, if they are all points, is this why matter can be compressed all the way into a black hole singularity or a singularity at the big bang? because you cant ever reach the edge of a point, just get infinitesimally close to it.
  2. jcsd
  3. Jul 19, 2013 #2


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    Staff: Mentor

    1. To the best of our knowledge and our most accurate experiments, elementary particles are point particles.

    2. We have no idea. They just do.

    3. Mmm...kind of. Once you get down to the quantum level, "size" becomes a little weird when you can't say where a particle is until you observe it. There's also the fact that particles can go "through" each other, certain ones (bosons) can exist in the exact same spot in at the same time, and multiple other factors.

    4. No. Consider an electron. It can NEVER EVER occupy the same spot at the same time and in the same state as another electron. The quantum mechanics rules do not allow this. Inside of massive stars that go supernova, a funny thing happens. In the collapsing core, all this gravity tries to do just that. It tries to force all these electrons and other particles into the same spot. But what happens is that the electrons and the protons give gravity the finger and disappear, leaving behind a neutron instead of an electron and a proton! Neither the proton nor the electron exist anymore! Instead we have an entirely different particle.

    It is believed that if you keep ramping up the gravity, the fundamental particles that make up a neutron start doing something similar to what the electron and proton did. The neutrons are believed to break down and the Quarks that they were composed of start to interact with other quarks from other neutrons and the whole supercompressed core is one giant nucleon.

    The key here is that the particles are not compressed down to an infitesimal point. At least not yet. Since we can't see behind the event horizon of a black hole, we can't really know for sure what goes on. Many scientists do not believe that a singularity actually exists, instead believing that the infinities that arise from the math are a product of our incomplete understanding of how physics works at this scale.
  4. Jul 19, 2013 #3
    Perfect. Thanks Drakkith
  5. Jul 21, 2013 #4
    It may be more accurate to say: In the Standard Model, fundamental particles are modelled as point particles.
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