DOCSLIB.ORG

A11throughout His History Man

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A11throughout His History Man 11throughout his history man has at describing phenomena that take place over theory, which gives a unified description of wanted to know the dimensions distance intervals of order 10–16 centimeter quantum electrodynamics (QED) and the of his world and his place in it. or larger. These theories may be valid to weak interactions, and quantum chromo- A Before the advent of scientific in- much shorter distances, but that remains to dynamics (QCD), which is an attractive can- struments the universe did not seem very be tested experimentally. A fully unified the- didate theory for the strong interactions. We large or complicated. Anything too small to ory will have to include gravity and therefore will argue that, although Einstein’s theory of detect with the naked eye was not known, will probably have to describe spatial struc- gravity (also called general relativity) has a and the few visible stars might almost be tures as small as 10–33centimeter, the funda- somewhat different status among physical touched if only there were a higher hill mental length (determined by Newton’s theories, it should also be included in the nearby. gravitational constant) in the theory of grav- standard model. If it is, then the standard Today, with high-energy particle ac- ity. History suggests cause for further model incorporates all observed physical celerators the frontier has been pushed down caution: the record shows many failures re- phenomena—from the shortest distance in- to distance intervals as small as 10-]6 cen- sulting from attempts to unify the wrong, too tervals probed at the highest energy ac- timeter and with super telescopes to cos- few, or too many physical phenomena. The celerators to the longest distances seen by mological distances. These explorations end of the 19th century saw a huge but modern telescopes. However, despite its ex- have revealed a multifaceted universe; at unsuccessful effort to unify the description of perimental successes, the standard model re- first glance its diversity appears too com- all Nature with thermodynamics. Since the mains unsatisfying, among its shortcomings plicated to be described in any unified man- second law of thermodynamics cannot be is the presence of a large number of arbitrary ner. Nevertheless, it has been possible to derived from Newtonian mechanics, some constants that require explanations. It re- incorporate the immense variety of ex- physicists felt it must have the most funda- mains to be seen whether the next level of perimental data into a small number of mental significance and sought to derive the unification will provide just a few insights quantum field theories that describe four rest of physics from it. Then came a period of into the standard model or will unify all basic interactions—weak, strong, electro- belief in the combined use of Maxwell’s elec- natural phenomena. magnetic, and gravitational. Their mathe- trodynamics and Newton’s mechanics to ex- The second question examined in this es- matical formulations are similar in that each plain all natural phenomena. This effort was say is twofold: What are the possible strate- one can be derived from a local symmetry. also doomed to failure: not only did these gies for generalizing and extending the stan- This similarity has inspired hope for even theories lack consistency (Newton’s equa- dard model, and how nearly do models based greater progress: perhaps an extension of the tions are consistent with particles traveling on these strategies describe Nature? A central present theoretical framework will provide a faster than the speed of light, whereas the problem of theoretical physics is to identify single unified description of all natural Lorentz invariant equations of Maxwell are the features of a theory that should be ab- phenomena. not), but also new experimental results were stracted, extended, modified, or generalized. This dream of unification has recurred emerging that implied the quantum structure From among the bewildering array of the- again and again, and there have been many of matter. Further into this century came the ories, speculations, and ideas that have successes: Maxwell’s unification of elec- celebrated effort by Einstein to formulate a grown from the standard model, we will tricity and magnetism; Einstein’s unification unified field theory of gravity and elec- describe several that are currently attracting of gravitational phenomena with the tromagnetism. His failure notwithstanding, much attention. geomeh-y of space-time; the quantum-me- the mathematical form of his classical theory We focus on two extensions of established chanical unification of Newtonian mechan- has many remarkable similarities to the concepts. The first is called supersymmetry; ics with the wave-like behavior of matteL the modern efforts to unify all known fundamen- it enlarges the usual space-time symmetries quantum-mechanical generalization of elec- tal interactions. We must be wary that our of field theory, namely, Poincar6 invariance, trodynamics; and finally the recent unifica- reliance on quantum field theory and local to include a symmetry among the bosons tion of electromagnetism with the weak symmetry may be similarly misdirected, al- (particles of integer spin) and fermions force. Each of these advances is a crucial though we suppose here that it is not. (particles of half-odd integer spin). One of component of the present efforts to seek a Two questions will be the central themes the intriguing features of supersymmetry is more complete physical theory. of this essay. First, should we believe that the that it can be extended to include internal Befo,re the successes of the past inspire too theories known today are the correct compo- symmetries (see Note 2 in “Lecture Notes— much optimism, it is important to note that a nents of a truly unified theory? The compo- From Simple Field Theories to the Standard unified theory will require an unprecedented nent theories are now so broadly accepted Model). In the standard model internal local extrapolation. The present optimism is gen- that they have become known as the “stan- symmetries play a crucial role, both for erated by the discovery of theories successful dard model.” They include the electroweak classifying elementary particles and for de- 74 Summer/Fall 1984 LOS ALAMOS SCIENCE Newton’s Gravity Classical Orlglns ++ - I Einstein’s Gravity Quantum Development of Mechanics Quantum Theories T Quantum Electrodynamics Yang-Mills 5 Theories Electroweak Model Supergravity SU(2) x u(1) E I Chromodynamics I SU(3) I I J / Kaluza-Klein “Grand” Unification Theories //~u Extended Supergravity Development of Gravitational Theories Including Other Forces Superstrings I Fig. 1. Erolution of fundamental theories of Nature from the direct and well-established extension, or theoretical gen - clajsicaljie!d theories of .Vewton and Maxwell to the grand- erali:ation. The wide arrow s~’mboii:es the goal of presenr tvt theoretical conjectures of toda~. ‘The relationships among research, the unification of quantum fle[d theories n’ith these theories are discussed in the text. Solid lines indicate a gravit~’. 1()$! \] \\ I()$. .>( 11-\( 1 \ll:ll,ll L, 1.,11I(IM .< termining the form of the interactions among ories are encouraging because some of them there exists a gauge field and its correspond- them. The electroweak theory is based on the reduce, in a certain limit, to the only super- ing particle, which is a vector boson (spin-1 internal local symmetry group SU(2) X U(l) gravity theories that are likely to generalize particle) that mediates the interaction be- (see Note 8) and quantum chromodynamics the standard model. Moreover, whereas tween particles. Quantum electrodynamics on the internal local symmetry group SU(3). supergravity fails to give the standard model has just one independent local symmetry Gravity is based on space-time symmetries: exactly, a superstring theory might succeed. transformation, and the photon is the vector general coordinate invariance and local It seems that superstring theories can be boson (or gauge particle) mediating the inter- Poincari symmetry. It is tempting to try to formulated only in ten dimensions. action between electrons or other charged unify all these symmetries with supersym- Figure 1 provides a road map for this particles. Furthermore, tbe local symmetry metry. essay, which journeys from the origins of the dictates the exact form of the interaction. Other important implications of super- standard model in classical theory to the The interaction Lagrangian must be of the symmetry are that it enlarges the scope of the extensions of the standard model in super- form e.P’(.x),4Y(.x),where .P(.x) is the current classification schemes of the basic particles gravity and superstrings. These extensions density of the charged particles and A ~(x) is to include fields of different spins in the same may provide extremely elegant ways to unify the field of the vector bosons. The coupling multiplet, and it helps to solve some tech- the standard model and are therefore attract- constant e is defined as the strength with nical problems concerning large mass ratios ing enormous theoretical interest. It must be which the vector boson interacts with the that plague certain efforts to derive the stan- cautioned, however, that at present no ex- current. The hypothesis that all interactions dard moclel. Most significantly, if supersym- perimental evidence exists for supersym- are mediated by vector bosons or, equi- metry is made to be a local symmetry, then it metry or extra dimensions. valently, that they originate from local sym- automatically implies a theory of gravity, metries has been extended to the weak and called supergravity, that is a generalization of then to the strong interactions. Einstein’s theory. Supergravity theories re- Review of the Standard Model quire the unification of gravity with other Weak Interactions. Before the present under- kinds of interactions, which may be, in some We now review the standard model with standing of weak interactions in terms of future version, the electroweak and strong particular emphasis on its potential for being local symmetry, Fermi’s 1934 phenomeno- interacticms.
Load more

Recommended publications
  • Particles-Versus-Strings.Pdf
    Particles vs. strings http://insti.physics.sunysb.edu/~siegel/vs.html In light of the huge amount of propaganda and confusion regarding string theory, it might be useful to consider the relative merits of the descriptions of the fundamental constituents of matter as particles or strings. (More-skeptical reviews can be found in my physics parodies.A more technical analysis can be found at "Warren Siegel's research".) Predictability The main problem in high energy theoretical physics today is predictions, especially for quantum gravity and confinement. An important part of predictability is calculability. There are various levels of calculations possible: 1. Existence: proofs of theorems, answers to yes/no questions 2. Qualitative: "hand-waving" results, answers to multiple choice questions 3. Order of magnitude: dimensional analysis arguments, 10? (but beware hidden numbers, like powers of 4π) 4. Constants: generally low-energy results, like ground-state energies 5. Functions: complete results, like scattering probabilities in terms of energy and angle Any but the last level eventually leads to rejection of the theory, although previous levels are acceptable at early stages, as long as progress is encouraging. It is easy to write down the most general theory consistent with special (and for gravity, general) relativity, quantum mechanics, and field theory, but it is too general: The spectrum of particles must be specified, and more coupling constants and varieties of interaction become available as energy increases. The solutions to this problem go by various names -- "unification", "renormalizability", "finiteness", "universality", etc. -- but they are all just different ways to realize the same goal of predictability.
    [Show full text]
  • Planck Mass Rotons As Cold Dark Matter and Quintessence* F
    Planck Mass Rotons as Cold Dark Matter and Quintessence* F. Winterberg Department of Physics, University of Nevada, Reno, USA Reprint requests to Prof. F. W.; Fax: (775) 784-1398 Z. Naturforsch. 57a, 202–204 (2002); received January 3, 2002 According to the Planck aether hypothesis, the vacuum of space is a superfluid made up of Planck mass particles, with the particles of the standard model explained as quasiparticle – excitations of this superfluid. Astrophysical data suggests that ≈70% of the vacuum energy, called quintessence, is a neg- ative pressure medium, with ≈26% cold dark matter and the remaining ≈4% baryonic matter and radi- ation. This division in parts is about the same as for rotons in superfluid helium, in terms of the Debye energy with a ≈70% energy gap and ≈25% kinetic energy. Having the structure of small vortices, the rotons act like a caviton fluid with a negative pressure. Replacing the Debye energy with the Planck en- ergy, it is conjectured that cold dark matter and quintessence are Planck mass rotons with an energy be- low the Planck energy. Key words: Analog Models of General Relativity. 1. Introduction The analogies between Yang Mills theories and vor- tex dynamics [3], and the analogies between general With greatly improved observational techniques a relativity and condensed matter physics [4 –10] sug- number of important facts about the physical content gest that string theory should perhaps be replaced by and large scale structure of our universe have emerged. some kind of vortex dynamics at the Planck scale. The They are: successful replacement of the bosonic string theory in 1.
    [Show full text]
  • Unification of Gravity and Quantum Theory Adam Daniels Old Dominion University, [email protected]
    Old Dominion University ODU Digital Commons Faculty-Sponsored Student Research Electrical & Computer Engineering 2017 Unification of Gravity and Quantum Theory Adam Daniels Old Dominion University, [email protected] Follow this and additional works at: https://digitalcommons.odu.edu/engineering_students Part of the Elementary Particles and Fields and String Theory Commons, Engineering Physics Commons, and the Quantum Physics Commons Repository Citation Daniels, Adam, "Unification of Gravity and Quantum Theory" (2017). Faculty-Sponsored Student Research. 1. https://digitalcommons.odu.edu/engineering_students/1 This Report is brought to you for free and open access by the Electrical & Computer Engineering at ODU Digital Commons. It has been accepted for inclusion in Faculty-Sponsored Student Research by an authorized administrator of ODU Digital Commons. For more information, please contact [email protected]. Unification of Gravity and Quantum Theory Adam D. Daniels [email protected] Electrical and Computer Engineering Department, Old Dominion University Norfolk, Virginia, United States Abstract- An overview of the four fundamental forces of objects falling on earth. Newton’s insight was that the force that physics as described by the Standard Model (SM) and prevalent governs matter here on Earth was the same force governing the unifying theories beyond it is provided. Background knowledge matter in space. Another critical step forward in unification was of the particles governing the fundamental forces is provided, accomplished in the 1860s when James C. Maxwell wrote down as it will be useful in understanding the way in which the his famous Maxwell’s Equations, showing that electricity and unification efforts of particle physics has evolved, either from magnetism were just two facets of a more fundamental the SM, or apart from it.
    [Show full text]
  • Unification of Nature's Fundamental Forces
    Unification of Nature’s Geoffrey B. West Fredrick M. Cooper Fundamental Forces Emil Mottola a continuing search Michael P. Mattis it was explicitly recognized at the time that basic research had an im- portant and seminal role to play even in the highly programmatic en- vironment of the Manhattan Project. Not surprisingly this mode of opera- tion evolved into the remarkable and unique admixture of pure, applied, programmatic, and technological re- search that is the hallmark of the present Laboratory structure. No- where in the world today can one find under one roof such diversity of talent dealing with such a broad range of scientific and technological challenges—from questions con- cerning the evolution of the universe and the nature of elementary parti- cles to the structure of new materi- als, the design and control of weapons, the mysteries of the gene, and the nature of AIDS! Many of the original scientists would have, in today’s parlance, identified themselves as nuclear or particle physicists. They explored the most basic laws of physics and continued the search for and under- standing of the “fundamental build- ing blocks of nature’’ and the princi- t is a well-known, and much- grappled with deep questions con- ples that govern their interactions. overworked, adage that the group cerning the consequences of quan- It is therefore fitting that this area of Iof scientists brought to Los tum mechanics, the structure of the science has remained a highly visi- Alamos to work on the Manhattan atom and its nucleus, and the devel- ble and active component of the Project constituted the greatest as- opment of quantum electrodynamics basic research activity at Los Alam- semblage of scientific talent ever (QED, the relativistic quantum field os.
    [Show full text]
  • Dark Energy and Dark Matter in a Superfluid Universe Abstract
    Dark Energy and Dark Matter in a Superfluid Universe1 Kerson Huang Massachusetts Institute of Technology, Cambridge, MA , USA 02139 and Institute of Advanced Studies, Nanyang Technological University, Singapore 639673 Abstract The vacuum is filled with complex scalar fields, such as the Higgs field. These fields serve as order parameters for superfluidity (quantum phase coherence over macroscopic distances), making the entire universe a superfluid. We review a mathematical model consisting of two aspects: (a) emergence of the superfluid during the big bang; (b) observable manifestations of superfluidity in the present universe. The creation aspect requires a self‐interacting scalar field that is asymptotically free, i.e., the interaction must grow from zero during the big bang, and this singles out the Halpern‐Huang potential, which has exponential behavior for large fields. It leads to an equivalent cosmological constant that decays like a power law, and this gives dark energy without "fine‐tuning". Quantum turbulence (chaotic vorticity) in the early universe was able to create all the matter in the universe, fulfilling the inflation scenario. In the present universe, the superfluid can be phenomenologically described by a nonlinear Klein‐Gordon equation. It predicts halos around galaxies with higher superfluid density, which is perceived as dark matter through gravitational lensing. In short, dark energy is the energy density of the cosmic superfluid, and dark matter arises from local fluctuations of the superfluid density 1 Invited talk at the Conference in Honor of 90th Birthday of Freeman Dyson, Institute of Advanced Studies, Nanyang Technological University, Singapore, 26‐29 August, 2013. 1 1. Overview Physics in the twentieth century was dominated by the theory of general relativity on the one hand, and quantum theory on the other.
    [Show full text]
  • Quantum Vacuum Energy Density and Unifying Perspectives Between Gravity and Quantum Behaviour of Matter
    Annales de la Fondation Louis de Broglie, Volume 42, numéro 2, 2017 251 Quantum vacuum energy density and unifying perspectives between gravity and quantum behaviour of matter Davide Fiscalettia, Amrit Sorlib aSpaceLife Institute, S. Lorenzo in Campo (PU), Italy corresponding author, email: [email protected] bSpaceLife Institute, S. Lorenzo in Campo (PU), Italy Foundations of Physics Institute, Idrija, Slovenia email: [email protected] ABSTRACT. A model of a three-dimensional quantum vacuum based on Planck energy density as a universal property of a granular space is suggested. This model introduces the possibility to interpret gravity and the quantum behaviour of matter as two different aspects of the same origin. The change of the quantum vacuum energy density can be considered as the fundamental medium which determines a bridge between gravity and the quantum behaviour, leading to new interest- ing perspectives about the problem of unifying gravity with quantum theory. PACS numbers: 04. ; 04.20-q ; 04.50.Kd ; 04.60.-m. Key words: general relativity, three-dimensional space, quantum vac- uum energy density, quantum mechanics, generalized Klein-Gordon equation for the quantum vacuum energy density, generalized Dirac equation for the quantum vacuum energy density. 1 Introduction The standard interpretation of phenomena in gravitational fields is in terms of a fundamentally curved space-time. However, this approach leads to well known problems if one aims to find a unifying picture which takes into account some basic aspects of the quantum theory. For this reason, several authors advocated different ways in order to treat gravitational interaction, in which the space-time manifold can be considered as an emergence of the deepest processes situated at the fundamental level of quantum gravity.
    [Show full text]
  • Aspects of Loop Quantum Gravity
    Aspects of loop quantum gravity Alexander Nagen 23 September 2020 Submitted in partial fulfilment of the requirements for the degree of Master of Science of Imperial College London 1 Contents 1 Introduction 4 2 Classical theory 12 2.1 The ADM / initial-value formulation of GR . 12 2.2 Hamiltonian GR . 14 2.3 Ashtekar variables . 18 2.4 Reality conditions . 22 3 Quantisation 23 3.1 Holonomies . 23 3.2 The connection representation . 25 3.3 The loop representation . 25 3.4 Constraints and Hilbert spaces in canonical quantisation . 27 3.4.1 The kinematical Hilbert space . 27 3.4.2 Imposing the Gauss constraint . 29 3.4.3 Imposing the diffeomorphism constraint . 29 3.4.4 Imposing the Hamiltonian constraint . 31 3.4.5 The master constraint . 32 4 Aspects of canonical loop quantum gravity 35 4.1 Properties of spin networks . 35 4.2 The area operator . 36 4.3 The volume operator . 43 2 4.4 Geometry in loop quantum gravity . 46 5 Spin foams 48 5.1 The nature and origin of spin foams . 48 5.2 Spin foam models . 49 5.3 The BF model . 50 5.4 The Barrett-Crane model . 53 5.5 The EPRL model . 57 5.6 The spin foam - GFT correspondence . 59 6 Applications to black holes 61 6.1 Black hole entropy . 61 6.2 Hawking radiation . 65 7 Current topics 69 7.1 Fractal horizons . 69 7.2 Quantum-corrected black hole . 70 7.3 A model for Hawking radiation . 73 7.4 Effective spin-foam models .
    [Show full text]
  • Introduction to Loop Quantum Gravity
    Introduction to Loop Quantum Gravity Abhay Ashtekar Institute for Gravitation and the Cosmos, Penn State A broad perspective on the challenges, structure and successes of loop quantum gravity. Addressed to Young Researchers: From Beginning Students to Senior Post-docs. Organization: 1. Historical & Conceptual Setting 2. Structure of Loop Quantum Gravity 3. Outlook: Challenges and Opportunities – p. 1. Historical and Conceptual Setting Einstein’s resistance to accept quantum mechanics as a fundamental theory is well known. However, he had a deep respect for quantum mechanics and was the first to raise the problem of unifying general relativity with quantum theory. “Nevertheless, due to the inner-atomic movement of electrons, atoms would have to radiate not only electro-magnetic but also gravitational energy, if only in tiny amounts. As this is hardly true in Nature, it appears that quantum theory would have to modify not only Maxwellian electrodynamics, but also the new theory of gravitation.” (Albert Einstein, Preussische Akademie Sitzungsberichte, 1916) – p. • Physics has advanced tremendously in the last 90 years but the the problem of unification of general relativity and quantum physics still open. Why? ⋆ No experimental data with direct ramifications on the quantum nature of Gravity. – p. • Physics has advanced tremendously in the last nine decades but the the problem of unification of general relativity and quantum physics is still open. Why? ⋆ No experimental data with direct ramifications on the quantum nature of Gravity. ⋆ But then this should be a theorist’s haven! Why isn’t there a plethora of theories? – p. ⋆ No experimental data with direct ramifications on quantum Gravity.
    [Show full text]
  • Lessons from Perturbative Unitarity in Graviton Scattering Amplitudes
    Lessons from perturbative unitarity in graviton scattering amplitudes Yu-tin Huang National Taiwan University Nima Arkani-Hamed, Tzu-Chen Huang, Ellis Ye Yuan, Warren Siegel Strings and Fields 2016 YITP The cartoon story of string theory, The presence of world-sheet ! high energy softness, infinite excitations (solution to UV completion) There is much more to the story than the world-sheet Two apparently unrelated developments: • Constraints from/of perturbative completion: • Positivity: For any effective field theory, L = φrφ + ai Oi (φ) The existence of unitary, Lorentz invariant UV completion ! ai > 0 for certain operators Adams, Arkani-Hamed, Dubovsky, Nicolis, Rattazzi • Causality: For gravitation interactions, any perturbative correction to R produce time advancement interactions. It’s cure require infinite number of higher spin states Camanho, Edelstein, Maldacena, Zhiboedov • World-sheet based field theory amplitudes • Witten’s twistor string theory: Topological B-model in CP3j4. • “Scattering equations” Cachazo, He, Yuan X ki · ka Scattering Equations : Ea = = 0 σ − σ i6=a i a Massless kinematics parameterizes the moduli space of n-punctured Riemann spheres The “physical” origin of string theory is likely to have nothing to do with the world-sheet In this talk I will pursuit this line of thought by answering • What constraints does perturbative unitarity imposes on the S-matrix? For massive scalar, see Caron-Huot, Komargodski, Sever, Zhiboedov • Are these “world-sheet” field theory a limit of string theory ? We already have a well
    [Show full text]
  • Fundamental Elements and Interactions of Nature: a Classical Unification Theory
    Volume 2 PROGRESS IN PHYSICS April, 2010 Fundamental Elements and Interactions of Nature: A Classical Unification Theory Tianxi Zhang Department of Physics, Alabama A & M University, Normal, Alabama, USA. E-mail: [email protected] A classical unification theory that completely unifies all the fundamental interactions of nature is developed. First, the nature is suggested to be composed of the following four fundamental elements: mass, radiation, electric charge, and color charge. All known types of matter or particles are a combination of one or more of the four fundamental elements. Photons are radiation; neutrons have only mass; protons have both mass and electric charge; and quarks contain mass, electric charge, and color charge. The nature fundamental interactions are interactions among these nature fundamental elements. Mass and radiation are two forms of real energy. Electric and color charges are con- sidered as two forms of imaginary energy. All the fundamental interactions of nature are therefore unified as a single interaction between complex energies. The interac- tion between real energies is the gravitational force, which has three types: mass-mass, mass-radiation, and radiation-radiation interactions. Calculating the work done by the mass-radiation interaction on a photon derives the Einsteinian gravitational redshift. Calculating the work done on a photon by the radiation-radiation interaction derives a radiation redshift, which is much smaller than the gravitational redshift. The interaction between imaginary energies is the electromagnetic (between electric charges), weak (between electric and color charges), and strong (between color charges) interactions. In addition, we have four imaginary forces between real and imaginary energies, which are mass-electric charge, radiation-electric charge, mass-color charge, and radiation- color charge interactions.
    [Show full text]
  • Electromagnetic Unification 84 - Què És La Ciència? 150Th Anniversary of Maxwell's Equations Written by Augusto Beléndez
    Electromagnetic Unification 13/03/15 10:39 CATALÀ ESPAÑOL search... HOME JOURNAL ANNUAL REVIEW SUBSCRIPTIONS BOOKS NEWS O2C MÈTODE TV Home ARTICLE Issues ( All covers ) Electromagnetic Unification 84 - Què és la ciència? 150th Anniversary of Maxwell's Equations Written by Augusto Beléndez Compartir | 0 What Is Science? A Multidisciplinary Approach to Scientific Thought Winter 2014/15 116 pages PVP: 10.00 € Categories -- Select category -- Authors - Select an autor - By kind permission of the Master and Fellows of Peterhouse (Cambridge, UK) Picture of James Clerk Maxwell (1831-1879), who, together with Newton and Einstein, is considered one of the greats in the history of physics. His theory of the electromagnetic field was fundamental for the comprehension of natural phenomena and for the development of technology, specially for telecommunications. When we use mobile phones, listen to the radio, use the remote control, watch «At the beginning of the TV or heat up food in the microwave, we may not know James Clerk Maxwell is the nineteenth century, one to thank for making these technologies possible. In 1865, Maxwell published electricity, magnetism an article titled «A Dynamical Theory of the Electromagnetic Field», where he and optics were three stated: «it seems we have strong reason to conclude that light itself (including independent radiant heat, and other radiations if any) is an electromagnetic disturbance in the disciplines» form of waves propagated through the electromagnetic field according to electromagnetic laws» (Maxwell, 1865). Now, in 2015, we celebrate the 150th anniversary of Maxwell’s equations and the electromagnetic theory of light, events commemorating the «International Year of Light and Light-Based Technologies», declared by the UN.
    [Show full text]
  • PMEM and Unification
    Pre-metric electromagnetism as a path to unification. DAVID DELPHENICH Independent researcher Spring Valley, OH 45370, USA [email protected] It is shown that the pre-metric approach to Maxwell’s equations provides an alternative to the traditional Einstein- Maxwell unification problem, namely, that electromagnetism and gravitation are unified in a different way that makes the gravitational field a consequence of the electromagnetic constitutive properties of spacetime, by way of the dispersion law for the propagation of electromagnetic waves. Keyw ords: Pre-metric electromagnetism, Einstein-Maxwell unification problem, line geometry, electromagnetic constitutive laws 1. The Einstein-Maxwell unification problem. fundamental distinctions between them, as well. In particular, the analogy between mass and Ever since Einstein succeeded in accounting for charge was not complete, since at the time (and the presence of gravitation in the universe by to this point in time, as well), no one had ever showing how it was a natural consequence of the observed what one might call “negative” mass or curvature of the Levi-Civita connection that one “anti-gravitation.” Of course, the possibility that derived from the Lorentzian metric on the such a unification of gravitation and spacetime manifold, he naturally wondered if the electromagnetism might lead to such tantalizing other fundamental force of nature that was consequences has been an ongoing source of known at the time – namely, electromagnetism – impetus for the search for that theory. could also be explained in a similar way. Since Several attempts followed by Einstein and the best-accepted theory of electromagnetism at others (cf., e.g., [1] and part II of [2]) at the time (as well as the best-accepted “classical” achieving such a unification.
    [Show full text]