What is Strong force: Definition and 98 Discussions

In nuclear physics and particle physics, the strong interaction is one of the four known fundamental interactions, with the others being electromagnetism, the weak interaction, and gravitation. At the range of 10−15 m (1 femtometer), the strong force is approximately 137 times as strong as electromagnetism, 106 times as strong as the weak interaction, and 1038 times as strong as gravitation. The strong nuclear force confines quarks into hadron particles such as the proton and neutron. In addition, the strong force binds these neutrons and protons to create atomic nuclei, where it is called the nuclear force. Most of the mass of a common proton or neutron is the result of the strong force field energy; the individual quarks provide only about 1% of the mass of a proton.
The strong interaction is observable at two ranges and mediated by two force carriers. On a larger scale (about 1 to 3 fm), it is the force (carried by mesons) that binds protons and neutrons (nucleons) together to form the nucleus of an atom. On the smaller scale (less than about 0.8 fm, the radius of a nucleon), it is the force (carried by gluons) that holds quarks together to form protons, neutrons, and other hadron particles. In the latter context, it is often known as the color force. The strong force inherently has such a high strength that hadrons bound by the strong force can produce new massive particles. Thus, if hadrons are struck by high-energy particles, they give rise to new hadrons instead of emitting freely moving radiation (gluons). This property of the strong force is called color confinement, and it prevents the free "emission" of the strong force: instead, in practice, jets of massive particles are produced.
In the context of atomic nuclei, the same strong interaction force (that binds quarks within a nucleon) also binds protons and neutrons together to form a nucleus. In this capacity it is called the nuclear force (or residual strong force). So the residuum from the strong interaction within protons and neutrons also binds nuclei together. As such, the residual strong interaction obeys a distance-dependent behavior between nucleons that is quite different from that when it is acting to bind quarks within nucleons. Additionally, distinctions exist in the binding energies of the nuclear force of nuclear fusion vs nuclear fission. Nuclear fusion accounts for most energy production in the Sun and other stars. Nuclear fission allows for decay of radioactive elements and isotopes, although it is often mediated by the weak interaction. Artificially, the energy associated with the nuclear force is partially released in nuclear power and nuclear weapons, both in uranium or plutonium-based fission weapons and in fusion weapons like the hydrogen bomb.The strong interaction is mediated by the exchange of massless particles called gluons that act between quarks, antiquarks, and other gluons. Gluons are thought to interact with quarks and other gluons by way of a type of charge called color charge. Color charge is analogous to electromagnetic charge, but it comes in three types (±red, ±green, ±blue) rather than one, which results in a different type of force, with different rules of behavior. These rules are detailed in the theory of quantum chromodynamics (QCD), which is the theory of quark–gluon interactions.

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  1. C

    Is Brian Cox right to claim that Gravity is a strong force for large masses?

    I watched a program of his in which it was claimed that since mass bends space in accordance to General Relativity, then in the case of very large stars it becomes a strong force to the point of being able to crush a star to a single nucleus (Neutron Stars) or less (Black Holes). His argument...
  2. nomadreid

    On a point of logic in the Higgs vs strong force origin of mass

    Recently, in the Scientific American blog http://blogs.scientificamerican.com/observations/2012/11/29/person-of-the-year-nomination-for-higgs-boson-riddled-with-errors/?WT_mc_id=SA_CAT_physics_20121130 the author criticizes Time Magazine for its science reporting, which of course is nothing...
  3. Drakkith

    Role of Strong Force in Neutron Stars

    Does the strong force have any major role in neutrons stars other than obviously holding individual nuclei together? Would low energy neutrons tend to "clump" together in the core?
  4. C

    What is the nature of the residual strong force?

    Reading about the strong force and the residual strong force I'm a bit confused about the interaction. Largely it keeps mentioning it the result of particle exchange and mentions that it has infinite distance, but that the residual strong force doesn't have infinite distance. However, it doesn't...
  5. G

    The strong force and the weak force

    I'm still highly confused about the weak force. Every time I read about it I get something along the lines of it is responsible for beta decay which to my understanding is when a proton or a neutron exits from the atom's nucleus. One thing I have trouble understanding is that if the strong...
  6. R

    At how many femtometers does strong force cease to exist?

    At 2.5 femtometer away from a quark the strong force is said to significantly loose power and become insignificant. At how many femtometers does the strong force completely loose any amount of tug?
  7. S

    Relationship between dark energy and the strong force

    Hello, I am a general physicist, pursuing it for fun. I work in solar, and the other day while driving up to Sacramento I had a interesting train of thought. From the data we have collected, one interpretation could be that on average, the universe is expanding in every direction at an...
  8. P

    Is the Strong Force causing any of the effects of a Black Hole?

    In a Black Hole, is gravity the only force drawing matter and energy into it, or deep inside at a minute scale (3 femtometers), is the Strong Force also operant ? Bonus questions: 1) Would it be true to say that without the Strong Force, there would be no matter? 2) In the "splitting of the...
  9. P

    Is it possible that the Strong Force and gravity are the same thing?

    Because the Strong Force and gravity are both forces that attract, could they actually be the same thing, manifesting in different ways at different distances?
  10. D

    How analogous is the strong force to photon/electron interaction in QED?

    ; Can someone explain to me (in layman's terms,) how it might be possible to associate the interactions of the up/down quarks in the strong nuclear force as analogous to the way electrons and photons interact in quantum electrodynamics ?
  11. johann1301

    Electromagnetic and strong force

    I have heard that the strong nuclear force is stronger then the electromagnetic force at short ranges, "Up to two and a half times the proton diameter". Ok, so i have an approximation of the length it dominates over the electromagnetic force, but i don't know where the force starts from; is it...
  12. N

    Why must strong force theory be QCD?

    Please teach me this: Why must strong interaction theory be QCD(SU(3)) theory?Because asymptotic freedom of strong force is the characteristic of any non-Abelian gauges theories.E.g why must it not be SU(2)? Thank you very much for your kind helping.
  13. Spinnor

    If we could slowly vary the strength of the strong force.

    Say we could slowly vary the strength of the strong force. What would happen to the "size" of proton if the strength of the strong force tended to zero and infinity? Thanks for any help!
  14. edpell

    Calculating the Potential Well of Neutron Capture by the Strong Force

    If I have a low energy neutron and I bring it close to a nucleus it will be captured when it gets close enough. How can I calculate the shape of the potential well of the nucleus for neutron capture? I keep reading that it is due to the strong force, which I agree with. But it is some...
  15. J

    Explaining role of Pions in Strong force interactions.

    Let me start off by saying that I am no professor of any kind, i am simply a high school student in way over his head concerning particle interactions. Without a class to teach me, i have used the magic of the internet to attempt to get a rudimentary understanding of these interactions. I...
  16. S

    Strong Force alternative theory besides gluon

    Hi I am just a newb with interest in physics. Maybe someone can help me out: Is there any theory that explains the strong force or bonding together of protons and neutrons in the center of the atom with a vortex in the center of the atom similar to a black holes vortex. And theorizes that...
  17. S

    Mass Defect & the Strong Force in Nucleons

    I was wondering how mesons or the strong force is accounted for in mass defect. Nucleons individually have more mass then when they are bound together in a nucleus of an atom. I saw a teacher/professor speak on youtube. He said the binding energy (strong force) was calculated as part of the...
  18. N

    Is electro-weak force intermediate for strong force happening?

    Please teach me this: In collider of lepton scattering from hadron,I think that the electro-weak force is interaction between lepton and hadron, then hadron being excited,because of this inducing the strong force has an effect of producing new hadrons(if possible).So that electro-weak force is...
  19. D

    Is there a 'classical' equation for the strong force?

    Sorry if this is a bit stupid, but I have absolutely no grasp on chromodynamics or really any nucleic forces... Is there a 'classical' way of expressing the strong force in an equation? By classical, I mean extremely simple, approximate way of describing it for two point particles. Like a...
  20. P

    Strong force, quarks, hadrons.

    I'm reading The Lightness of Being by Frank Wilczek. The strong force falls off rapidly with distance. And yet when we attempt to separate two quarks the force increases enormously. I assumed the strong force acted between hadrons (= groups of quarks) and between quarks but this...
  21. E

    Exploring Strong Force Interaction in 2s/2as Tetraquark Decay

    I'm working on a problem involving decay of a 2 strange/2 anti-strange tetraquark particle. 4 sample decay diagrams are given and I am to describe them and choose which is most prevalent. In on diagram, two of the strange/anti-strange quarks become two down/anti-down quarks via gluon through...
  22. N

    Does the strong force affect the weak force

    Hello, can anyone help. Does the strong force affect the weak force in any way. Or do both not interact with each other. Thank you.
  23. M

    Splitting Atoms: Exploring the Strong Force

    If the strong force is what is used to describe the attraction in the atomic nucleus, how is it possible to split atoms without them constantly re-pairing? a free charge doesn't seem like it would exist due to the strong force. I'm missing something right?
  24. J

    Understanding the Repulsive Strong Force and its Role in Nucleons and Quarks

    Hi, I have been taught at school that the strong force is responsible for holding the nucleons together in the nucleus but becomes repulsive below about 1.5 femtometres. I now read that the strong force is also responsible for holding the quarks together inside the nucleons, although the...
  25. H

    Nuclear fusion and strong force

    I want to know the work of strong force during fusion of two atoms (say hydrogen), It is known that atoms need to get close enough to fuse but what does strong force especially "color charges" or "gluon" perform which causes fusion?
  26. Spinnor

    Range of strong force as strength gets weaker.

    Say we can set the strength of the strong force weaker, can the glouns then range further and further from a quark? Can we eventually get the strong force to look like the electromagnetic force as far as the range of the force is concerned? Thanks for any help!
  27. R

    Understanding the Strong Force: Protons and Neutrons in Collision

    I apologize for the very simple question, but I find often the simplest questions are the ones not answered in books. If a free-floating proton collides with a free-floating neutron, do they get bound together by the strong nuclear force? Let's say it's a low-energy collision - both...
  28. edpell

    Unraveling the Strong Force: Color vs Favor

    Hi this is a very elementary question. Is the strong force a color force? Or a favor force? Or a combination color and favor? Also with photons (massless) we have a r^-2 force but with massless gluons the force increase with r (do not know as what function) how can this be? Thanks.
  29. B

    What is the relationship between the strong force and E=mc2?

    I have read that the strength of the strong interaction between two quarks is roughly the same as the weight of a 10 tonne truck (i.e. 105 N). There is a relationship between Force and distance and work and energy and mass (and I am aware of the extent to which Newtonian mechanics is...
  30. M

    Does strong force = gravity at very small distances?

    this is probably either a really dumb question, or just a dumb question. But with my remedial knowledge of these fundamental forces it seems a logical question to ask. Gravity is deemed the weakest force, but maybe that's just a range related perspective. It gets stronger with decreasing...
  31. N

    Question about the nature of electrons and the strong force

    How can electrons that make up a current not repel each other at far distances due to their like charges? I understand why protons are bunched up together , because of the strong force. Though electrons are not packed up against one another like protons and neutrons, they are still a short...
  32. C

    Could gravity be residual strong force?

    If nucleons are held together by residual strong force could could gravity be residual residual strong force reaching outside the atom, causing atoms to tend to clump together?
  33. P

    Are photons affected by the strong force? The weak force?

    Can light travel through an atom? If yes, how will it emerge? If no, why not? Will it interact with any subatomic particles?
  34. P

    Is the weak and strong force the same force?

    Hello, I'm a novice in this field, but there is one thing I have been wondering about for a long time. Maby you could help me understand it? I think it must be enough to only use the quark-quark forces to describe all nuclear reactions, even things like n-> p+e+v, but it is perhaps a lot more...
  35. L

    Could Gravity and the Strong Force Be the Same Phenomenon at Different Scales?

    Is it possible that gravity and the strong force could be the same just on a smaller scale giving it different properties?
  36. T

    Kindergarden question about the Strong Force: its origin

    (If you don't feel like reading all three paragraphs just skip to the sentence written in bold.) So I am autodidacting myself through the world of (quantum) physics, just the concepts of course, no math and I finally got to a stage where I can use my present knowledge to (partially) deduce...
  37. T

    How do the Veneziano amplitudes explain the strong force?

    I Heard That the gamma function explains the strong nuclear force . \Gamma \left( z \right) = \int\limits_0^\infty {t^{z - 1} } e^{ - t} dt How does it explain the Force? Thanks
  38. L

    The speed of light, gravity, strong force, weak force

    I could benefit from someone shedding some light on a couple of questions that I have regarding the speed of various entites: 1) It seems that the speed of gravity, e.g, if the sun disappeared, is the speed of light WRT things I've read. What is it that would inherently cause gravity to travel...
  39. wolram

    Unravelling the Mysteries of the Strong Force

    Is the strong force (carried) by elemenary particles or does this force exsist every where in the universe, so that no matter where particles are the strong force can act on them, sorry if this is a crapy question but i do not know.
  40. O

    Strong force, low energy proton scattering

    Homework Statement A beam of low energy protons is observed to scatter elastically from a target of neutrons. Sketch the variation of the differential cross section with the resulting scattering angle and comment on a characteristic feature of the strong force than can be deduced...
  41. H

    Lack of understanding of energy, quarks, and the strong force

    Hello, Here I go again :-p I don't understand a few things, let me all questions put in a paragraph so that I don't miss anything What is an energy? (I can't understand the definition provided by the encyclopedia) And, what's up with the vacuum energy? If no particles are there, how can energy...
  42. J

    Neutron Stars: Strong Force, Density & Black Holes

    Is a neutron star held together mainly by the strong force? Are they dense enough so that this is the case, or is gravity the only thing to consider? What about black holes?
  43. Evo

    Understanding the Difference: Gravity vs. Strong Force Explained and Calculated

    I have heard a number of times that the force of gravity is fairly insignificant compared to such forces as the strong force. Why is this, and how can one mathematically compute the differences in force? [Moderator's note: @Evo isn't the true OP of this thread. The true OP requested deletion...
  44. M

    Discovering the Strong Force: The History of its Discovery

    Even a brief study of the history of the events that led to the discovery of the strong force is of great interest. The first significant event in the chain of events which led to an understanding of the forces operating within the atomic nucleus was the discovery of radio activity. It was...
  45. curious george

    Question about reactions and the strong force

    I have a problem on my homework that lists several different reactions involving K mesons and asks which of them can happen via the strong interaction. I've listed a couple of them below, and I'm hoping that someone can tell me why these can or can't proceed via the strong interaction: (K-)...
  46. T

    TornadoCreator's theory: graviational effect of quarks and strong force

    Wouldn't it be true to say that as E=mc(sqared) that a high engergy particle also has high mass simply because if we revert to the therory of imcertainty (i think its called that) in which the errors to which we record everything reach such a large value that they are infact exceptionally larger...
  47. T

    Graviational effect of quarks and strong force

    with intense gravity the strong force between quarks are weakened. would it be possible that under extreme gravitational effects that quarks from other atoms join to make the theoretical tetraquark?
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