Physics
Fundamental Forces
Fundamental forces are the four basic interactions in nature: gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. These forces govern the behavior of all matter and energy in the universe. Each force has specific characteristics and ranges of influence, and they play a crucial role in shaping the structure and behavior of the physical world.
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11 Key excerpts on "Fundamental Forces"
eBook - PDF- SachchidaNand Shukla(Author)
- 2023(Publication Date)
- Arcler Press(Publisher)
The particle The Study of Elementary Particles 118 interaction between elementary elements can be identified as fundamental interaction. 5.1. FUNDAMENTAL INTERACTION Fundamental interactions—the forces of nature governing the particles that make up you and everything in your environment—are irreducible. Fundamentally, they do not need to be explained further. That is, they lack factors that account for their existence as a whole. The four forces (gravitational, electromagnetic, weak nuclear forces, and strong nuclear forces) simply are. Our quest to understand the fundamental physics of nature has revealed a rich collection of physical phenomena to explore with sophisticated experiments that probe smaller and smaller distances and stronger fields. It has been a spectacular journey so far. Fundamental interactions are physical forces that act between elementary particles and are responsible for most of the physical phenomena we experience in our daily lives. For example, when a magnet is placed on a metal surface, or two magnets attract or repel each other due to their magnetic charges, several fundamental interactions are involved. Perhaps the best-known example is visible light, which is actually a form of electromagnetic radiation. Electromagnetism is one of four fundamental interactions in nature; others include the strong and weak nuclear force and gravity. The fourth primary interaction is the weak interaction. The three Fundamental Forces are sometimes described as the “constituents” of all matter, since these forces are thought to be the causes for all other forces that can be measured (Jaeckel and Ringwald, 2010). Fundamental Interactions provide the force through which elementary particles interact. The different types of fundamental interactions explain the behavior of forces between ordinary objects, such as a proton and an electron into a hydrogen atom or the attraction of a magnet for steel.
eBook - PDF- James E. Dodd, Ben Gripaios(Authors)
- 2020(Publication Date)
- Cambridge University Press(Publisher)
Part II Basic Particle Physics 5 The Fundamental Forces 5.1 Introduction It is an impressive demonstration of the unifying power of physics to realise that all the phenomena observed in the natural world can be attributed to the effects of just four Fundamental Forces. These are the familiar forces of gravity and electromagnetism, and the not-so-familiar weak and strong nuclear forces (generally referred to as the ‘weak’ and ‘strong’ forces). Still more impressive is the fact that the phenomena occurring in the everyday world can be attributed to just two: gravity and electromagnetism. This is because only these forces have significant effects at observable ranges. The effects of the weak and strong nuclear forces are confined to within, at most, 10 −15 m of their sources. With this in mind, it is worthwhile summaris- ing a few key facts about each of the four forces before going on to look at the variety of phenomena they display in our laboratories. In each case we are interested in the sources of the force and the intrinsic strength of the interactions to which they give rise. We are interested also in the space–time properties of the force: how it propagates through space and how it affects the motions of particles under its influence. Finally, we must consider both the macroscopic (or classical) description of the forces (where appropriate) and the microscopic (or quantum-mechanical) picture (where possible). 5.2 Gravity Gravity is by far the most familiar of the forces in human experience, governing phenomena as diverse as falling apples and collapsing galaxies. At the non- relativistic level, the source of the gravitational force is mass and, because there is no such thing as negative mass, this force is always attractive. Furthermore, it is independent of all other attributes of the bodies upon which it acts, such as electric charge, spin, direction of motion, etc.
eBook - PDF- Yuri A Berezhnoy(Author)
- 2005(Publication Date)
- WSPC(Publisher)
Chapter 2 Fundamental Interactions 2.1 Gravitational Interaction Physics is concerned with matter: its structure and motion. The motion of matter is due to certain forces acting between bodies. The motion of galaxies and stars, of planets and comets, of electrons in TV sets and atoms, of nucleons and quarks in atomic nuclei, radioactive decays of atomic nuclei and elementary particles as well as all various processes in the Universe are caused by interactions between different physical objects. So it is not surprising that some of the most important questions in physics pertain to the study of these interactions. Over two millennia ago, the Greek philosopher Aristotle theorized that all substance in the Universe consisted of four elements — earth, air, fire, and water — and that these were subject to the action of two forces. The first was the force of gravity, which attracted earth and water downwards. The second was a force of lightness, which served to attract fire and air upwards. Thus, Aristotle divided all of Nature into substances and forces. This approach has persisted in physics until the present day. Now, there are four known types of interactions: gravitational, electromagnetic, and the strong and weak nuclear forces. Let us consider each in turn. The gravitational interaction, by intensity, is the weakest of all the in-teractions known to us. The gravitational forces have a universal character. This means that all matter is subject to them; this is what the law of univer-sal gravitation states. The range of gravitational forces is infinite. Gravita-tional forces are attractive. Gravitational interaction is mainly manifested between macroscopic bodies; it determines the motions of various cosmic objects: galaxies, stars, planets, etc. In the world of elementary particles, gravitational interaction is not directly apparent because of the very small 41 42 The Quantum World of Nuclear Physics masses of the particles.
eBook - PDFQuestioning the Universe
Concepts in Physics
- Ahren Sadoff(Author)
- 2008(Publication Date)
- Chapman and Hall/CRC(Publisher)
The force that holds the atom together is not some special new force, but is just due to the electri-cal attraction of the negatively charged electrons to the positively charged protons in the nucleus. Similarly, different atoms interact by the attraction or repulsion of the electrons and protons in one atom acting on the electrons and protons of another atom. All the other forces in the second column are due to the interaction of atoms (e.g., muscle atoms, air atoms in the wind), so all forces in that column are due to the electromagnetic force. 24 Questioning the Universe: Concepts in Physics Finally, there are the strong and weak nuclear forces. They do not directly affect our daily lives since they only act over nuclear or subnuclear dimensions, which are much, much smaller than atomic dimensions. They do affect us indirectly since they are responsible for holding the nucleus together (so we can have atoms) and for cer-tain types of radioactive nuclear decays. They are also very important in powering the sun, which is the ultimate source of energy for us here on earth. So, of all the myriad forces we may know of, there are only four. We believe these four—gravity, electromagnetic, strong nuclear, and weak nuclear—are the Fundamental Forces of nature. But our most modern theories carry this reduction (or unification) of forces even further. We believe, but have not confirmed yet, that at the instant of the creation of the universe, what we call the big bang, there was only one primordial, fundamental force. As the universe expanded and cooled, this single force took on different forms until there were the four forms we have today. This is an example of one of the most important principles in physics today: unifica-tion . This idea says that many things that are apparently different are, in fact, closely related and are really just different forms of the same thing.
eBook - PDFThe Mechanical Universe
Mechanics and Heat, Advanced Edition
- Steven C. Frautschi, Richard P. Olenick, Tom M. Apostol, David L. Goodstein(Authors)
- 2008(Publication Date)
- Cambridge University Press(Publisher)
Table 8.1 summarizes the four Fundamental Forces of nature, their respective ranges, and their respective strengths (as estimated for the forces acting between two protons at short range). Note the utter unimportance of gravity on the atomic scale of 10~ e cm. Only on the scale of a mountain, 1 km or 10 13 atoms on a side, 1 km 3 or 10 39 atoms in volume, does the mass become iarge enough to compensate the relative strength factor of 1(T 39 . Tabie 8.1 Characteristics of the Four Fundamental Forces Force Strong Electromagnetic Weak Gravitational Relative strength 1 10 2 I0 2 10 39 Range lCT 13 cm Infinite ]{T l6 cm Infinite Importance Holds nucleus together Controls everyday phenom-ena - friction, tensions, etc. Nuclear transmutation Organizes large-scale phe-nomena and universe 8.3 CONTACT FORCES The Fundamental Forces of nature are aaion-at-a-distance forces: their effects can be experienced when the particles are not in contact. A second category of forces is contact forces. These are forces which two objects exert on each other when they are physically in contact with each other, as for example, when a book rests on a table.* Contact forces are not Fundamental Forces; instead, they arise from electric forces acting in complicated ways among enormous numbers of atoms. The contact forces are described by empirical rules, which are experimental sum-maries of the net result of all the complications. Most of these empirical descriptions were deduced by eighteenth-century scientists who were unaware of the underlying fun-damental forces. Even today, when the Fundamental Forces are better understood, quan-titative deduction of the contact forces from fundamental laws remains difficult and the empirical rules are still commonly used. *The implication that contact forces drop abruptly lo zero when two bodies separate, though valid on macroscopic distance scales, is an idealization. On the atomic scale the contact force falls off continuously though rapidly when the distance of separation increases, as one would expect from the electrical origin of the force.
eBook - PDF- Fayyazuddin, Riazuddin;;;(Authors)
- 2000(Publication Date)
- WSPC(Publisher)
Chapter 1 INTRODUCTION 1.1 Fundamental Force Particle physics is concerned with the fundamental constituents of matter and the Fundamental Forces through which the fundamen-tal constituents interact among themselves. Until about 1932, only four particles, namely the proton (p), the neutron (n), the electron (e) and the neutrino (u) were regarded as the ultimate constituents of matter. Of these four par-ticles, two, the proton and the electron are electrically charged. The other two are electrically neutral. The neutron and proton form atomic nuclei, the electron and nucleus form atoms while the neutrino comes out in radioactivity, i.e. the neutron decays into a proton, an electron and a neutrino. Each of these particles, called a fermion, spins and exists in two spin (or polarization) states called left-handed (i.e. appears to be spinning clockwise as viewed by an observer that it is approaching) and right-handed (i.e. spinning anti-clockwise) spin states. One may add a fifth particle, the pho-ton to this list. The photon is a quantum of electromagnetic field. It is a boson and carries spin 1, is electrically neutral and has zero mass, due to which it has only two spin directions or it has only transverse polarization. It is a mediator of electromagnetic force. A general feature of quantum field theory is that each particle has its own antiparticle with opposite charge and magnetic moment, but with same mass and spin. Accordingly we have four antiparti-cles viz., the antiproton (p), the positron (e + ), the antineutron (n) 1 2 Introduction and antineutrino (u). The four particles experience four types of forces: i. The Gravitational Force This is a force of attraction between two particles and is propor-tional to their gravitational charges, namely their masses. It is a long range force, controls the motion of planets and galaxies, gov-erns the law of falling bodies, and determines the overall character of our Universe.
eBook - PDF- Fayyazuddin, Riazuddin;;;(Authors)
- 2011(Publication Date)
- WSPC(Publisher)
Chapter 1 Introduction 1.1 Fundamental Forces Particle physics is concerned with the fundamental constituents of matter and the fundamental “forces” through which the fundamental constituents interact among themselves. Until about 1932, only four particles, namely the proton ( p ), the neutron ( n ), the electron ( e ) and the neutrino ( ν ) were regarded as the ultimate constituents of matter. Of these four particles, two, the proton and the electron are electrically charged. The other two are electrically neutral. The neutron and proton form atomic nuclei, the electron and nucleus form atoms while the neutrino comes out in radioactivity, i.e. the neutron decays into a proton, an electron and a neutrino. Each of these particles, called a fermion, spins and exists in two spin (or polarization) states called left-handed (i.e. appears to be spinning clockwise as viewed by an observer that it is approaching) and right-handed (i.e. spinning anti-clockwise) spin states. One may add a fifth particle, the photon to this list. The photon is a quantum of electromagnetic field. It is a boson and carries spin 1, is electrically neutral and has zero mass, due to which it has only two spin directions or it has only transverse polarization. It is a mediator of electromagnetic force. A general feature of quantum field theory is that each particle has its own antiparticle with opposite charge and magnetic moment, but with same mass and spin. Accordingly we have four antiparticles viz., the antiproton ( p ), the positron ( e + ), the antineutron ( n ) and antineutrino ( ν ). The four particles experience four types of forces: 1 2 Introduction 1.1.1 The Gravitational Force This is the force of attraction between two particles and is proportional to their masses and inversely proportional to the square of distance between them. It controls the motion of planets and galaxies and also governs the law of falling bodies.
eBook - PDFUnderstanding The Universe: From Quarks To The Cosmos
From Quarks to the Cosmos
- Donald Lincoln(Author)
- 2004(Publication Date)
- World Scientific(Publisher)
Research is to see what everybody has seen and to think what nobody else has thought. — Albert Szent-Györgi If the universe were only occupied by the particles described in the preceding chapter, the universe would be a very lonely place indeed. Particles would zip hither and yon, never giving one another so much as a “How do you do?” Electrons would not be bound to atomic nuclei and, with no atoms; there would be no molecules, no cells, no us. And since readers wouldn’t exist, I wouldn’t bother writing this book. Luckily, in addition to the interesting particles about which we are now familiar, there also exist forces that bind the particles together into useful configurations. As alluded to in earlier chapters, we know of four distinct forces with very different properties. The first thing that we will discuss is the character of the various forces, but then we will discuss a new and interesting idea. The existence of forces implies that new particles exist. These particles carry the various forces. This is a non-intuitive concept and we will discuss it in detail when appropriate. c h a p t e r 4 ❖ Forces: What Holds it All Together 147 At our present level of knowledge, there appear to exist four forces. These forces are gravity, the electromagnetic force, the strong (or nuclear) force and the radiation-causing weak force. Gravity is per-haps the most familiar. It keeps us on Earth and guides the stars and planets through the cosmos. Gravity is always an attractive force, which means gravity will always make two particles want to move closer to one another. When one thinks about forces, an important question is always “What governs the strength of the force?” For gravity, just three things are relevant: (a) the mass of each of the two objects, (b) the distance separating the centers of the two objects and (c) a constant factor which is related to how strong the gravity force is, once the other two factors are taken into account.
eBook - PDFUnderstanding The Universe: From Quarks To Cosmos (Revised Edition)
From Quarks to the Cosmos
- Donald Lincoln(Author)
- 2012(Publication Date)
- World Scientific(Publisher)
146 Research is to see what everybody has seen and to think what nobody else has thought. — Albert Szent-Györgi If the universe were only occupied by the particles described in the preceding chapter, the universe would be a very lonely place indeed. Particles would zip hither and yon, never giving one another so much as a “How do you do?” Electrons would not be bound to atomic nuclei and, with no atoms; there would be no molecules, no cells, no us. And since readers wouldn’t exist, I wouldn’t bother writing this book. Luckily, in addition to the interesting particles about which we are now familiar, there also exist forces that bind the particles together into useful configurations. As alluded to in earlier chapters, we know of four distinct forces with very different properties. The first thing that we will discuss is the character of the various forces, but then we will discuss a new and interesting idea. The existence of forces implies that new particles exist. These particles carry the various forces. This is a non-intuitive concept and we will discuss it in detail when appropriate. c h a p t e r 4 ❖ Forces: What Holds it All Together At our present level of knowledge, there appear to exist four forces. These forces are gravity, the electromagnetic force, the strong (or nuclear) force and the radiation-causing weak force. Gravity is per-haps the most familiar. It keeps us on Earth and guides the stars and planets through the cosmos. Gravity is always an attractive force, which means gravity will always make two particles want to move closer to one another. When one thinks about forces, an important question is always “What governs the strength of the force?” For gravity, just three things are relevant: (a) the mass of each of the two objects, (b) the distance separating the centers of the two objects and (c) a constant factor which is related to how strong the gravity force is, once the other two factors are taken into account.
- Menahem Simhony(Author)
- 1994(Publication Date)
- World Scientific(Publisher)
The electromagnetic interaction dominates in the atomic and molecular realms, and in the creation, propagation, and absorption of electromagnetic radiation. 113 The electromagnetic interaction is responsible for holding the atomic electrons and nuclei in atoms (again, together with inertia!). It is also responsible for all forms of binding atoms into molecules (molecular bonds), and of binding atoms, ions, and molecules into bodies of atomic matter. All other physical interactions in atomic matter, elastic and plastic, hydrostatic (buoyancy) and frictional, thermal and acoustic, can thus be deduced to the electromagnetic interaction, with the participation of gravitation (and inertia, of course). Furthermore, the interactions within living cells, and the signals they send to each other are electromagnetic, too. The third fundamental interaction is the strong nuclear interaction. It coagulates (fuses) elementary nuclear particles into light nuclei, and light nuclei into heavier ones, when the distances between them are fractions of a fermi. The strong nuclear interaction is a hundred times stronger than the electrostatic interaction between charged nuclear particles (at a distance of 1 fm between them). Fourth is the weak nuclear interaction, which brings together nuclear particles. It is orders of magnitude weaker than the strong nuclear interaction, but acts at distances up to slightly above a femtometer. Certain facts made some researchers state that the weak nuclear interaction can be deduced to the electromagnetic interaction. This would reduce the number of fundamental interactions to three. However others did not accept the reduction and still consider the weak nuclear interaction a fundamental one, with its name changed to electroweak interaction. Both the strong and the weak nuclear interactions are responsible for the stability of nuclei and for nuclear transformations. These interactions cause all nuclear processes and the radioactivity of materials.
eBook - PDF- Robert M. Metzger(Author)
- 2023(Publication Date)
- Wiley(Publisher)
Quarks (Tables 1.2 and 1.3) were proposed in 1964 by Zweig 17 and Gell-Mann 18 to establish order in this zoo. Within the nucleus, the inter-nucleon “strong” force was traditionally thought of as being mediated by pions (themselves combinations of two quarks). The nuclear “shell model” assigns quantum numbers to the protons and neutrons that have merged to form a certain nucleon. Certain “magic values” of these nuclear quantum numbers explain why certain nuclei are more stable (have longer lives) than others. Efforts to unify all four forces of Table 1.1 into a single grand unified theory have failed. All of eighteenth and nine- teenth century mathematical physics was based on continua, on the solution of second-order partial differential equations (PDEs), and on microscopic extensions of macroscopic Newtonian ideas of distance-dependent potentials. As we shall see, classical mechanics, electrodynamics, and quantum mechanics (in its wave mechanical formulation) all have potential energy functions U(r) which are some function of the inter-particle distance r. This works well if the particles themselves are much smaller than the distances that typically separate them, and when experiments can test the distance dependence of the potentials directly. What are we to do when the range of the strong forces are so short (Table 1.1), of the order of magnitude of the presumed particle sizes? Much progress was made nevertheless. In 1960, electrical and weak forces were merged by Glashow 19 into the electro- weak theory.
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