Les nouvelles du vide - 01 janvier 2006- les Archives 2004 - Le Dossier Environnement - L'Engineering du Vide Quantique: une nouvelle discipline! - Le début d'une nouvelle vision holistique? - Le coin des sceptiques: La Roue de l'Histoire - Les conférences - les articles de synthèse, etc...
20 dec 2005 (68 pp)
(+)Institute of Physics , University of Freiburg, Germany, email@example.com
(++) Institute for Theoretical Physics, University of Zürich, Switzerland, firstname.lastname@example.org
17 December 2005 , NewScientist.com, par Amanda Gefter
Extraits: "Second was the
discovery that the value of the cosmological constant -
the energy of empty space which contributes to the expansion rate of
the universe - seems absurdly improbable, and nothing in fundamental
physics is able to explain why. I remember when Steven Weinberg first
suggested that the cosmological constant might be anthropically
determined - that it has to be this way otherwise we would not be here
to observe it. I was very impressed with the argument, but troubled by
it. Like everybody else, I thought the cosmological constant was
probably zero - meaning that all the quantum fluctuations that make up
the vacuum energy cancel out, and gravity alone affects the expansion
of the universe. It would be much easier to explain if they cancelled
out to zero, rather than to nearly zero. The discovery that there is a
non-zero cosmological constant changed everything. Still, those two
things were not enough to tip the balance for me."
par B.G. Sidharth
International Institute for Applicable Mathematics & Information Sciences, Hyderabad (India) & Udine (Italy)
B.M. Birla Science Centre, Adarsh Nagar, Hyderabad - 500 063 (India)
Résumé: After many fruitless decades of trying to unify electromagnetism and gravitation, it is now being realized that this can be done only in discrete spacetime, as indeed the author had demonstrated. In this context, a unified description of gravitation and electromagnetism is provided within the framework of a gauge like formulation. "These latest theories discard the differentiable spacetime of earlier approaches and rely on a lattice like approach to spacetime, wherein there is a minimum fundamental interval which replaces the point space time of earlier theories. Indeed as Hooft has remarked, “It is some what puzzling to the present author why the lattice structure of space and time had escaped attention from other investigators up till now....”
Résumé: The Kerr-Newman solution has
g=2 as that of the Dirac
electron and is considered as a model of spinning particle in general
relativity. The Kerr geometry changes cardinally our representations on
the role of gravity in the particle physics. We show that the Kerr
gravitational field has a stringy local action and a topological
peculiarity which are extended up to the Compton distances, and also a
strong non-local action playing the key role in the
mass-renormalization and regularization of singularities. The
Kerr-Newman gravity determines the structure of spinning particle in
the form of a relativistically rotating disk, a highly oblate bag of
the Compton radius. Interior of this bag consists of an AdS or dS
``false vacuum'', depending on the correlation of the mass density and
charge. In the same time, the local action of gravitational field may
be considered as negligible for regularized particle.
Extraits: "The used in QED mass renormalization is
universally recognized due to an incredible exactness of its
predictions. Although its origin lies in the classical theory of a
pointlike electron, there are serious problems with physical
interpretation and mathematical correctness of this procedure.(...) We
show that the mass renormalization and regularization of the
singularities in the Kerr- Newman source are realized by gravitational
field in a very natural manner.(...) We show that the Kerr
in the Compton the strong local field having a stringy structure, a
nontrivial topological peculiarity and has a strong non-local action
playing the key role in the mass- renormalization.(...) Some of the
terms may be divergent, but the total result will not be changed, since
divergences will always be compensated by contribution from
gravitational term. It shows that, due to the strong non-local action,
gravity has to be very essential for elementary particles, on the
distances which are very far from the considered usually Planck scale."
"Regularization of the zero-point radiation
(...)Twofoldedness of the Kerr geometry confirms this point of view, since the out-going radiation on the “positive” out-sheet of the metric is compensated by an in-going radiation on the “negative” in-sheet, see Fig. 1. So, physically, there is no reason for the lost of mass by radiation. It shows, that the term F31 = γ 1 ˜r has to be identified with the vacuum zero-point field. In this case the electromagnetic excitations on the Kerr background may be interpreted as a resonance of the zero-point fluctuations on the (superconducting) source of the Kerr spinning particle [13, 9]."
F.W. Hehl, Yu.N. Obukhov, G.F. Rubilar , M. Blagojevic
15 pages, 1 figure - Journal-ref: Phys.Lett. A347 (2005) 14-24
Résumé: It has been observed since the time of Cartan, Kottler, and van Dantzig, that since the spacetime metric only enters into Maxwell's equations for electromagnetism by way of the Hodge star operator, and, more to the point, the metric structure of spacetime seems to follow from the propagation of electromagnetic waves, that perhaps one should regard the spacetime metric as a corollary to the electromagnetic structure of spacetime, and formulate the laws of electromagnetism in a metric-free fashion.
par G.E. Volovik
Low Temperature Laboratory, Helsinki University of Technology, P.O.Box 2200, FIN-02015 HUT, Finland
Abstract: The phenomenon of emergent physics in condensed-matter many-body systems has become the paradigm of modern physics, and can probably also be applied to high-energy physics and cosmology. This encouraging fact comes from the universal properties of the ground state (the analog of the quantum vacuum) in fermionic many-body systems, described in terms of the momentum-space topology. In one of the two generic universality classes of fermionic quantum vacua the gauge fields, chiral fermions, Lorentz invariance, gravity, relativistic spin, and other features of the Standard Model gradually emerge at low energy. The condensed-matter experience provides us with some criteria for selecting the proper theories in particle physics and gravity, and even suggests specific solutions to different fundamental problems. In particular, it provides us with a plausible mechanism for the solution of the cosmological constant problem, which I will discuss in some detail.
Department of Physics, Fudan University, Shanghai, 200433, China
Department of Physics, Portland State University, Portland, OR97207, U.S.A.
Email : email@example.com
Abstract: In order to clarify why the zero-point energy associated with the vacuum fluctuations cannot be a candidate for the dark energy in the universe, a comparison with the Casimir effect is analyzed in some detail. A principle of epistemology is stressed that it is meaningless to talk about an absolute (isolated) thing. A relative thing can only be observed when it is changing with respect to other things. Then a new conjecture of antigravity --the repulsive force between matter and antimatter derived from the modified Einstein field equation in general relativity-- is proposed. this is due to the particle-antiparticle symmetry based on a new understanding about the essence of special relativity. Its possible consequences in the theory of cosmology are discussed briefly, including a new explanation for the accelerating universe and gamma-ray-bursts.
Michael Levin and Xiao-Gang Wen
Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
(Dated: May, 2005)
We give an example of a purely bosonic model – a rotor model on the 3D cubic lattice – whose low energy excitations behave like massless U(1) gauge bosons and massless Dirac fermions. This model can be viewed as a "quantum ether ": a medium that gives rise to both photons and electrons. It illustrates a general mechanism for the emergence of gauge bosons and fermions known as " stringnet condensation." Other, more complex, string-net condensed models can have excitations that behave like gluons, quarks and other particles in the standard model. This suggests that photons, electrons and other elementary particles may have a unified origin: string-net condensation in our vacuum.
RADIO - De récentes interviews d'Edgar Günzig sont rediffusées par la RTBF les 18, 24, 25 et 31 décembre, 1er janvier. Sujet: LE VIDE
NB: Les émissions du samedi sont réécoutables durant une semaine via le site de Memo.
La dernière émission est écoutable via le lien: http://www.rtbf.be/media/radio/alademande/prem_curieux_1700/DI_play.m3u
© M. Hermans - T. Dang Vu, 1997-2006
Cette page a réalisée avec NAMO 4.04
Nombre de visites depuis le 11 novembre 2005: