[Paleopsych] SW: On the Aether and Broken Symmetry

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Theoretical Physics: On the Aether and Broken Symmetry
http://scienceweek.com/2005/sw050708-6.htm

    The following points are made by Frank Wilczek (Nature 2005 435:152):
    1) The concept that what we ordinarily perceive as empty space is in
    fact a complicated medium is a profound and pervasive theme in modern
    physics. This invisible inescapable medium alters the behavior of the
    matter that we do see. Just as Earth's gravitational field allows us
    to select a unique direction as up, and thereby locally reduces the
    symmetry of the underlying equations of physics, so cosmic fields in
    "empty" space lower the symmetry of these fundamental equations
    everywhere. Or so theory has it. For although this concept of a
    symmetry-breaking aether has been extremely fruitful (and has been
    demonstrated indirectly in many ways), the ultimate demonstration of
    its validity --cleaning out the medium and restoring the pristine
    symmetry of the equations -- has never been achieved: that is,
    perhaps, until now.
    2) In new work, Cramer et al.[1] claim to have found evidence that --
    for very brief moments, and over a very small volume
    --experimentalists working at the Relativistic Heavy Ion Collider
    (RHIC) at Brookhaven National Laboratory in New York have vaporized
    one symmetry-breaking aether, and produced a more perfect emptiness.
    This pioneering attempt to decode the richly detailed (in other words,
    complicated and messy) data emerging from the RHIC experiments is
    intricate[2], and it remains to be seen whether the interpretation
    Cramer et al. propose evolves into a consensus. In any case, they've
    put a challenge on the agenda, and suggested some concrete ways to
    tackle it.
    3) But what exactly is this underlying symmetry of nature that is
    broken by the aether? How is it broken, and how might it be restored?
    The symmetry in question is called chiral symmetry, and it involves
    the behavior of quarks, the principal constituents of the protons and
    neutrons in atomic nuclei (among other things). Chiral symmetry is
    easiest to describe if we adopt the slight idealization that the
    lightest quarks, the up quark (u) and down quark (d), are massless.
    (In reality their masses are small, on the scale of the energies in
    play, but not quite zero.) According to the equations of quantum
    chromodynamics (QCD), the theory that describes quarks and their
    interactions via the strong nuclear force, the possible
    transformations among quarks are very restricted. One rule is that
    u-quarks and d-quarks retain their "flavor" -- that is, a (u) never
    converts into a (d), nor a (d) into a (u).
    4) Quarks also, like the more familiar photons, have an intrinsic
    spin. If the spin axis is aligned with the direction of motion, then
    the sense of the rotation defines a handedness, known as chirality,
    rather like a left- or right-handed screw. The two possible states of
    chirality of a quark, left and right, are essentially the same concept
    as left and right circular polarization for photons. The fundamental
    interaction between quarks and gluons, to which we ultimately trace
    the strong nuclear force, conserves chirality as well as flavor. Thus
    a u-quark with left-handed chirality (written uL) never converts into
    a right-handed uR, and so on. But these extra conservation laws, which
    follow from the symmetry of QCD's equations, are too good to be true.
    In reality, one finds that although the rule forbidding changes of
    flavor holds true, there is no additional conservation law for
    chirality -- chiral symmetry is broken.
    5) The accepted explanation for this mismatch blames a form of aether.
    The idea is that there is such a powerful attractive interaction
    between uL-quarks and R-antiquarks (every quark has an antiquark with
    the opposite charge), and likewise between dL-quarks and R-antiquarks,
    that the energy gained from their attraction outweighs the cost of
    creating the particles in the first place. Thus, perfectly empty
    space, devoid of quarks, is unstable. One can lower the energy of the
    vacuum by filling it with bound uL-R and dL-R pairs (and their
    antiparticles, L-uR, L-dR). Physicists call this process the formation
    of the chiral condensate. In the stable state that finally results,
    the conservation of chirality is rendered ineffective, as space itself
    has become a reservoir containing, for example, an indefinite number
    of uL-quarks.[3-5]
    References (abridged):
    1. Cramer, J., Miller, G., Wu, J. & Yoon, J. -H. preprint at
    http://www.arxiv.org/nucl-th/0411031 (2004)
    2. Kolb, P. F. & Heinz, U. in Quark Gluon Plasma Vol. 3 (eds Hwa, R.
    C. & Wang, X.-N.) (World Scientific, Singapore, 2004); preprint at
    http://www.arxiv.org/nucl-th/0305084 (2003)
    3. Adcox, K. et al. (The PHENIX collaboration) Nucl. Phys. A
    (submitted); preprint at http://arxiv.org/nucl-ex/0410003 (2005)
    4. Adams, J. et al. (The STAR collaboration) Nucl. Phys. A
    (submitted); preprint at http://arxiv.org/nucl-ex/05010095 (2005)
    5. Back, B. B. et al. (The PHOBOS collaboration) Nucl. Phys. A (in the
    press); doi:10.1016/j.nuclphysa.2005.03.084 (2005)
    Nature http://www.nature.com/nature
    --------------------------------
    Related Material:
    ON THE ETHER CONCEPT IN PHYSICS
    Notes by ScienceWeek:
    In the late 19th century, what we now call "classical" physics
    incorporated the assumed existence of the "ether", a hypothetical
    medium believed to be necessary to support the propagation of
    electromagnetic radiation. The famous *Michelson-Morley experiment of
    1887 was interpreted as demonstrating the nonexistence of the ether,
    and this experiment became a significant prelude to the subsequent
    formulation of Einstein's *special theory of relativity. Although it
    is often stated outside the physics community that the ether concept
    was abandoned after the Michelson-Morley experiment, this is not quite
    true, since the classical ether concept has been essentially
    reformulated into several modern *field concepts.
    The following points are made by Frank Wilczek (Physics Today January
    1999):
    1) Isaac Newton (1642-1727) believed in a continuous medium filling
    all space, but his equations did not require any such medium, and by
    the early 19th century the generally accepted ideal for fundamental
    physical theory was to discover mathematical equations for forces
    between indestructible atoms moving through empty space.
    2) It was Michael Faraday (1791-1867) who revived the idea that space
    was filled with a medium having physical effects in itself... To
    summarize Faraday's results, James Clerk Maxwell (1831-1879) adapted
    and developed the mathematics used to describe fluids and elastic
    solids, and Maxwell postulated an elaborate mechanical model of
    electrical and magnetic fields.
    3) The achievement of Einstein (1879-1955) in his paper on special
    relativity was to highlight and interpret the hidden symmetry of
    Maxwell's equations, not to change them. The Faraday-Maxwell concept
    of electric and magnetic fields, as media or ethers filling all space,
    was retained by Einstein. Later, Einstein was dissatisfied with the
    particle-field dualism inherent in the early atomic theory, and
    Einstein sought, without success, a unified field theory in which all
    fundamental particles would emerge as special solutions to the field
    equations.
    4) Following Einstein, Paul Dirac (1902-1984) then showed that photons
    emerged as a logical consequence of applying the rules of quantum
    mechanics to Maxwell's electromagnetic ether. This connection was soon
    generalized so that particles of any sort could be represented as the
    small-amplitude excitations of quantum fields. Electrons, for example,
    can be regarded as excitations of an electron field, an ether that
    pervades all space and time uniformly. Our current and extremely
    successful theories of the *strong, electromagnetic, and weak forces
    are formulated as *relativistic quantum field theories with *local
    interactions.
    5) The author states: "Einstein first purified, and then enthroned,
    the ether concept. As the 20th century has progressed, its role in
    fundamental physics has only expanded. At present, renamed and thinly
    disguised, it dominates the accepted laws of physics."
    Physics Today http://www.physicstoday.org
    --------------------------------
    Notes by ScienceWeek:
    Michelson-Morley experiment of 1887: Conducted by Albert Michelson
    (1852-1931) and Edward Morley (1838-1923), the experiment attempted to
    measure the velocity of the Earth through the "ether" by using an
    interferometer to detect a difference in the speed of light in the
    direction of Earth's rotation from the speed perpendicular to this
    direction. No difference was observed, indicating the absence of an
    ether "wind".
    special theory of relativity: Proposed by Einstein in 1905, the
    special theory refers to inertial (non-accelerated) frames of
    reference. It assumes physical laws are identical in all frames of
    reference and that the speed of light in a vacuum is constant
    throughout the Universe and is independent of the speed of the
    observer. In general, the special theory gives a unified account of
    the laws of mechanics and electromagnetism (including optics). The
    companion theory, the general theory of relativity (1915), deals with
    general relative motion between accelerated frames of reference, and
    it is the general theory that led to Einstein's analysis of
    gravitation.
    field: In this context, in general, the term "field" refers to a
    physical quantity (e.g., electric or magnetic field) that varies from
    point to point in space.
    strong, electromagnetic, and weak forces: The fundamental forces
    currently identified in physics are the gravitational force, the
    electromagnetic force, the nuclear strong force, and the nuclear weak
    force. The nuclear strong force is the dominant force that acts
    between hadrons (e.g., the force that binds neutrons and protons in
    nuclei). (A "hadron" is any object made of *quarks and/or antiquarks).
    The weak force occurs between leptons (particles without internal
    structure, e.g., electrons, neutrinos) and hadrons (particles with
    internal structure, e.g., neutrons and protons); In general, the weak
    force is responsible for radioactivity.
    quarks and antiquarks: A quark is a hypothetical fundamental particle,
    having charges whose magnitudes are one-third or two-thirds of the
    electron charge, and from which the elementary particles may in theory
    be constructed. The antiquark is the antimatter quark entity. In
    general, antiparticles are homologs of elementary particles but with
    opposite charge. The positron, for example, is the antimatter particle
    homologous to the electron. Matter composed entirely of antiparticles
    is called "antimatter".
    relativistic quantum field theories: In general, a "quantum field
    theory" is any quantum mechanical theory in which particles are
    represented by fields whose normal modes of oscillation are quantized.
    The term is also used to refer to a quantum mechanical theory applied
    to systems having an infinite number of *degrees of freedom. Quantum
    electrodynamics, for example, is a particular quantum field theory
    describing the emission or absorption of photons by charged particles.
    "Relativistic quantum field theories" are used to describe fundamental
    interactions between elementary particles (which exhibit relativistic
    velocities, i.e., velocities approaching the speed of light).
    local interactions: In this context, a local interaction is an
    interaction between particles whose quantum mechanical wave functions
    are confined to a small region of a large system rather than being
    extended throughout the system.
    --------------------------------
    Related Material:
    ON FIELD THEORY IN PHYSICS
    Notes by ScienceWeek:
    In physics, a field is an entity that acts as intermediary in
    interactions between particles, and which is distributed over part or
    all of space, and whose properties are functions of space coordinates,
    and except for static fields, also functions of time. There is also a
    quantum-mechanical analog of this entity, in which the function of
    space and time is replaced by an operator at each point in space-time.
    The following points are made by Roman Jackiw (Proc. Natl. Acad. Sci.
    1998 95:12776):
    1) Present-day theory for fundamental processes (i.e., descriptions of
    elementary particles and forces) is phenomenally successful.
    Experimental data confirms theoretical prediction, and where accurate
    calculation and experiments are attainable, agreement is achieved to 6
    or 7 figures. Two examples: a) The helium atom ground state energy
    (*Rydbergs) is experimentally measured as -5.8071394 and theoretically
    calculated as -5.8071380. b) The muon magnetic dipole moment is
    experimentally measured as 2.00233184600 and theoretically calculated
    as 2.00233183478.
    2) The theoretical structure within which this success has been
    achieved is *local field theory, which offers a wide variety of
    applications, and which provides a model for fundamental physical
    reality as described by our theories of *strong, electroweak, and
    gravitational processes. No other framework exists in which one can
    calculate so many phenomena with such ease and accuracy.
    3) But is spite of these successes, today there is little confidence
    that field theory will advance our understanding of nature at its
    fundamental workings beyond what has already been achieved. Although
    in principle all observed phenomena can be explained by present-day
    field theory, these accounts are still imperfect, requiring ad hoc
    inputs. Moreover, because of conceptual and technical obstacles,
    classical gravity theory has not been integrated into the *quantum
    field description of nongravitational forces: *quantizing the *metric
    tensor of Einstein's theory produces a quantum field theory beset by
    infinities that apparently cannot be controlled.
    4) These shortcomings are actually symptoms of a deeper lack of
    understanding concerning *symmetry and symmetry breaking... Physicists
    are happy in the belief that Nature in its fundamental workings is
    essentially simple, but observed physical phenomena rarely exhibit
    overwhelming regularity. Therefore, at the very same time that we
    construct a physical theory with intrinsic symmetry, we must find a
    way to break the symmetry in physical consequences of the model.
    5) These problems have produced a theoretical impasse for over two
    decades, and in the absence of new experiments to channel theoretical
    speculation, some physicists have concluded that it will not be
    possible to make progress on these questions within field theory, and
    they have turned to a new structure, "*string theory". In field
    theory, the quantized excitations are point particles with point
    interactions, and this gives rise to the infinities. In string theory,
    the excitations are extended objects -- strings -- with nonlocal
    interactions; there are no infinities in string theory, and that
    enormous defect of field theory is absent.
    6) Yet in spite of its positive features, until now string theory has
    provided a framework rather than a definite structure, and a precise
    derivation of the *Standard Model has yet to be given. The author
    concludes: "On previous occasions when it appeared that quantum field
    theory was incapable of advancing our understanding of fundamental
    physics, new ideas and new approaches to the subject dispelled the
    pessimism. Today we do not know whether the impasse within field
    theory is due to a failure of imagination or whether indeed we have to
    present fundamental physical laws in a new framework, thereby
    replacing the field theoretic one, which has served us well for over
    100 years."
    Proc. Nat. Acad. Sci. http://www.pnas.org
    --------------------------------
    Notes by ScienceWeek:
    Rydbergs: A unit of energy used in atomic physics, value = 13.605698
    electronvolts.
    local field theory: In this context, "locality" is the condition that
    two events at spatially separated locations are entirely independent
    of each other, provided that the time interval between the events is
    less than that required for a light signal to travel from one location
    to the other. For example, the quantum mechanical wave function is a
    "local" field.
    strong, electroweak, and gravitational processes: The fundamental
    forces comprise the gravitational force, the electromagnetic force,
    the nuclear strong force, and the nuclear weak force. The
    "electroweak" interactions are a unification of the electromagnetic
    and nuclear weak interactions, and are described by the Weinberg-Salam
    theory (sometimes called "quantum flavordynamics"; also called the
    Glashow-Weinberg-Salam theory).
    quantum field description: In general, a quantum field theory is a
    quantum mechanical theory applied to systems having an infinite number
    of *degrees of freedom. The term is also used to refer to any quantum
    mechanical theory in which particles are represented by fields whose
    normal modes of oscillation are quantized (see below).
    degrees of freedom: In general, the number of independent parameters
    required to specify the configuration of a system.
    quantizing: In experimental physics, a quantized variable is a
    variable taking only discrete multiple values of a quantum mechanical
    constant. In theoretical physics, "quantizing" means the consistent
    application of certain rules that lead from classical to quantum
    mechanics. In general, "quantization" is a transition from a classical
    theory or a classical quantity to a quantum theory or the
    corresponding quantity in quantum mechanics.
    metric tensor: The mathematical statement (involving a set of
    quantities) that describes the deviation of the Pythagoras theorem in
    a curved space.
    symmetry and symmetry breaking: If a theory or process does not change
    when certain operations are performed on it, the theory or process is
    said to possess a symmetry with respect to those operations. For
    example, a circle remains unchanged under rotation or reflection, and
    a circle therefore has rotational and reflection symmetry. The term
    "symmetry breaking" refers to the deviation from exact symmetry
    exhibited by many physical systems, and in general, symmetry breaking
    encompasses both "explicit" symmetry breaking and "spontaneous"
    symmetry breaking. Explicit symmetry breaking is a phenomenon in which
    a system is not quite, but almost, the same for two configurations
    related by exact symmetry. Spontaneous symmetry breaking refers to a
    situation in which the solution of a set of physical equations fails
    to exhibit a symmetry possessed by the equations themselves.
    string theory: In particle physics, string theory is a theory of
    elementary particles based on the idea that the fundamental entities
    are not point-like particles but finite lines (strings), or closed
    loops formed by strings, the strings one-dimensional curves with zero
    thickness and lengths (or loop diameters) of the order of the Planck
    length of 10^(-35) meters.
    Standard Model: In particle physics, the Standard Model is a
    theoretical framework whose basic idea is that all the visible matter
    in the universe can be described in terms of the elementary particles
    leptons and quarks and the forces acting between them. Leptons are a
    class of point-like fundamental particles showing no internal
    structure and no involvement with the strong forces. A quark is a
    hypothetical fundamental particle, having charges whose magnitudes are
    one-third or two-thirds of the electron charge, and from which the
    elementary particles may in theory be constructed.