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What do they mean by force particles exactly?

  1. Nov 18, 2011 #1
    Can someone shed light on this. I'm VERY interested in high-energy/particle physics and I would love to have a little insight on this till I can study this stuff mathematically.

    Are they really particles? Or waves? Or both? Doesn't quantum mechanics apply?
     
  2. jcsd
  3. Nov 18, 2011 #2

    mathman

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    Quantum mechanics applies. There are four fundamental forces, each of which has a force particle.

    electromagnetism - photon
    strong nuclear - gluon
    weak nuclear - W and Z
    gravity - graviton (hypothetical - it has not been discovered)
     
  4. Nov 18, 2011 #3
    So why do they keep calling it a particle so much if its not a particle???
     
  5. Nov 18, 2011 #4

    ZapperZ

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    Let's not get hung up on semantics, here. Physicists often give labels to things without having to think what it would sound like to the rest of the population. What is more important is understanding what the physics mean, rather than visualizing what the name conjures up.

    Zz.
     
  6. Nov 18, 2011 #5

    ZapperZ

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    This is not just a "high energy/particle physics" issue. It is a more general formalism of quantum field theory. QFT is applicable in a huge variety of field, including condensed matter physics that is the domain of the stuff you use everyday in your electronics. Phonons, spinons, magnons, polarons, etc. are equivalent "force particles" that transfer interactions.

    Zz.
     
  7. Nov 18, 2011 #6
    First, I apology for my over-excitement haha, this is only just striking me to be interesting. However, don't mistaken that with a popular science fan-boy; its the math I'm really interested in.

    Actually at first I was uninterested in the standard model and particle physics because they kept conjuring everything up as particles. When I think of particles I usually envision the old view of matter. And I don't know why but I find particle physics much more exciting when I think of it from the point of view of quantum mechanics; including the wave-particle duality interpretation.
    This stuff sounds very interesting actually. I've always liked quantum field theory, quantum mechanics, etc. and general relativity but had a distaste for particle physics out of ignorance. Now I'm seeing the grander picture of physics and its beautiful!

    I find it very interesting that there all these different "particles" going on. Please clarify this for me...

    All these "particles" are different manifestations of wave functions(for lack of better words, I don't think that is the correct terminology). Different wave functions are classified and given names such as the pion, muon, etc. Force carriers such as w and z bosons are some type of ... okay I'm completely lost on what makes them different from other particles and what makes them force carriers.

    Gluons are very intriguing.. As I was researching on Brookhaven National Laboratory for an internship I stumbled upon a short video. It stated that the "gluon" force, for lack of better words, is the only known force that actually increases with distance!!

    Oh boy, I really can't dive into the mathematics of this now. Before quantum mechanics was interesting to me but now I see a whole different beast.
     
  8. Nov 19, 2011 #7
    There are not particle forces: the correct term is interaction, not force.

    Second, interactions in the Standard Model of particle physics are modelled using a kind special of particles that transmit the interaction (as a kind of messengers).

    Yes those particles are particles (all particles are particles, they are not waves).

    The Standard Model is based in QFT, which is a quantum theory, but it is not equivalent to quantum mechanics.
     
    Last edited: Nov 19, 2011
  9. Nov 19, 2011 #8
    Okay, interesting.

    That's messy. I don't see things that small as particles, there is so much complexity that labeling it as a particle seems unattractive to me. The word particle to me comes off as the classical picture of neutrons and protons.. but now we know they are much more complex than that. Zapperz mentioned that its just semantics, that it doesn't mean that its a particle from what I picture? I'm confused now.

    That strikes me as rather counter-intuitive, in the sense that QFT is based from quantum mechanics and you state that standard model doesn't hold true to the wave-particle duality interpretation?

    EDIT: So you also consider something as the neutrino which has been very elusive and thought to have 0 mass, simply a particle?

    To make sure we are not playing with semantics; I'm defining a particle as "a small localized object to which can be ascribed several physical properties such as volume or mass."

    Doesn't the particle-wave duality hold? It wouldn't make sense otherwise, at least to me.
     
    Last edited: Nov 19, 2011
  10. Nov 19, 2011 #9
    I do not know what do you mean by «the classical picture of neutrons and protons», but in the standard model of particle physics the concept of particle is well defined.

    I do not know how what I have said relates to what you say.

    The neutrino is one of the particles considered in the standard model.

    In the Standard Model (SM), particles are not defined as you define them. In fact, I think that I have never found a definition as yours in any field of physics.

    The «particle-wave duality» is a misname that has a historical basis, but that would be best abandoned from the language of modern physics. A particle (as defined in the SM) is always a particle and is always detected as a particle in experiments (e.g., at CERN).
     
    Last edited: Nov 19, 2011
  11. Nov 19, 2011 #10
    Can anyone confirm this?

    Your saying that wave-particle duality no longer holds true after quantum mechanics.. when quantum mechanics is the basis of much of our knowledge today? So then why are they studying Neutrino oscillations?

    I'm no expert and I don't have the mathematics behind this, can anyone else come in and put perspective on this.
     
  12. Nov 19, 2011 #11
    I think you get confused about what is a particle, and what is a wave function. A wave function tells you the probability of finding the particle in a particular location, but the particle is not the wave function! The wave function is just describing the state of the particle in position space.

    Also, the word oscillation in the context of neutrino oscillations has nothing to do with the wave particle duality in QM. The term oscillation comes from the fact that different flavors of neutrinos seem to change into each other (i.e. they oscillate between the different flavors, or types, of neutrinos). So don't confuse the term oscillation in this context with a wave oscillating, its a completely different concept. I would actually prefer the term neutrino mixing, as opposed to oscillation, but I didn't invent the term so I just go with it.
     
  13. Nov 20, 2011 #12
    I have not said that you say. Of course, quantum mechanics continues being correct and working. Neutrino oscillations have nothing to see with waves, the neutrino is always a particle, the oscillation refers to flavor.
     
  14. Dec 7, 2011 #13
    This has been bothering me for a while. I've been increasingly perplexed on what constitutes a wave and what doesn't?

    And if you hypothetically shoot Neutrinos to a double slit it won't have interference patterns?
     
  15. Dec 7, 2011 #14
    Neutrinos will have an interference pattern, then obey the same rules as the other particles. But when one says neutrino oscillation, it means something else. It means that they are oscillating between different flavors (different types). Neutrinos still have a wave function AND they can change type (oscillate between flavors).
     
  16. Dec 7, 2011 #15
    Well, juanrga was saying that they are strictly particles and don't have wave-like properties [unless I misunderstood]. Which was my question in the first place.

    &

    So then which is it??
     
  17. Dec 7, 2011 #16
    juanrga is right, particles are particles. The wave function is NOT the particle, it describes the state of the particle in position space (or momentum space, whichever basis you are using). The wave function (in the position basis) gives you the probability of finding the particle at a particular location, but that does not mean the wave function is the particle. Particles are still represented as point like objects.
     
  18. Dec 7, 2011 #17
    Yes - but you'd find it pretty hard to build a double-slit experiment for neutrinos!
     
  19. Dec 7, 2011 #18
    But how does this pointness manifest itself?

    I mean, I can understand that if, let's say an electron, hits a thin atom layer and makes a hole in it. The size of the hole can be smaller than the "size" of the wave function.

    Does the pointness only mean that an elementary particle does not have any internal structure?

    I have really hard time to picture how any particle could be represented as a point like objects in the sense that it would have zero volume.
     
  20. Dec 7, 2011 #19
    But you just told me that it has wave & particle like properties? So therefore wouldn't it be both a wave and a particle?

    Haha, which is why I added "hypothetical." =D
     
  21. Dec 8, 2011 #20
    Effectively you misunderstood what I have said, but others already corrected you.
     
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