Physics

This paper reviews some of the results of the Planck collaboration and shows how to compute the distance from the surface of last scattering, the distance from the farthest object that will ever be observed, and the maximum radius of a density fluctuation in the plasma of the CMB. It then explains how these distances together with well-known astronomical facts imply that space is flat or nearly flat and that dark energy is 69% of the energy of the universe.

In a companion article, the Clifford bundle over spacetime was used as a geometric framework for obtaining coupled Dirac and Einstein equations. Other forces may be incorporated using minimal coupling. Here the fundamental forces that are allowed within this framework are explicitly enumerated.

It is shown that there are 41 types of multivectors representing physical quantitites in non-relativistic physics in arbitrary dimensions within the formalism of Clifford Algebra. The classification is based on the action of three symmetry operations on a general multivector, namely, spatial inversion, time reversal, and a third that is introduced here, wedge reversion. It is shown that the traits of axiality and chirality are not good basis for classifying multivectors in arbitrary dimensions, and that introducing wedge reversion would allow for such a classification. Examples of these multivectors from non-relativistic physics are presented.

A proof is given for the Fourier transform for functions in a quantum mechanical Hilbert space on a non-compact manifold in general relativity. In the (configuration space) Newton-Wigner representation we discuss the spectral decomposition of the canonical operators and give a proof of the Parseval-Plancherel relation and the Born rule for linear superposition. We then discuss the representations of pure quantum states and their dual vectors, and construct the Fock space and the associated quantum field theory for Bose-Einstein and Fermi-Dirac statistics.

The quantum version of the free fall problem is a topic usually skipped in undergraduate Quantum Mechanics courses because its discussion would require to deal with wavepackets built on the Airy functions -- a notoriously difficult computation. Here, on the contrary, we show that the problem can be nicely simplified both for a single particle and for general many-body systems making use of a gauge transformation of the wavefunction corresponding to a change of the reference frame, from the laboratory frame of reference to the one comoving with the falling system. Within this approach, the quantum mechanics problem of a particle in an external gravitational potential -- counterpart of the free fall of a particle in Classical Mechanics each student is used to see from high-school -- reduces to a much simpler one where there is no longer gravitational potential in the Schrödinger equation. It is instructive to see that the same procedure applies also to many-body systems subjected to a two-body interparticle potential, function of the relative distances between the particles. This topic provides then a handful and pedagogical example of a quantum many-body system whose dynamics can be analytically described in simple terms.

In this letter, we investigate a quite recent new class of spin one-half fermions, namely \emph{Ahluwalia class-7 spinors}, endowed with mass dimensionality 1 rather than 3/2 , being candidates to describe dark matter. Such spinors, under the Dirac adjoint structure, belongs to the Lounesto's class-6, namely dipole spinors. Up to our knowledge, dipole spinor fields have Weyl spinor fields as their most known representative, nonetheless, here we explore the \emph{dark} counterpart of the dipole spinors, which represents eigenspinors of the chirality operator.

Frozen SUSY is the maximally suppressed Supersymmetric SU(5) Grand Unified Theory coupled to Supergravity. In Frozen SUSY, there is only one extra particle in addition to those that appear in the usual non-supersymmetric SU(5) Grand Unified Theory coupled to gravity. Frozen SUSY also restricts and improves the mass predictions, and the cosmological constant (at tree level). As a result, it uses 4 parameters to generate 14 reasonable predicted masses. The one extra particle is an extremely massive gravitino, which we call the Susyon. In Frozen SUSY, the Susyon is stable and it interacts purely through gravity. The Susyon might be a viable candidate for dark matter.

It was shown recently that unambiguous description of electromagnetic environments requires electromagnetic potentials; knowledge only of electric and magnetic fields is insufficient and can lead to error. Consequences of that demonstration are here applied to propagating fields, such as laser fields. Gauge invariance is replaced by symmetry preservation. This alteration makes it possible to understand how the known failure of the convergence of perturbation expansions in quantum electrodynamics (QED) follows from the fact that QED is incomplete; it does not contain its strong-field limit. Inherent in that demonstration are the strong-field coupling constant and the strong-field alteration of the mass shell of a charged particle. A variety of physically important consequences ensue, including the loss of guidance from Feynman diagrams. The meaning of tests for the precision of QED is questioned since such evaluations apply only to perturbative QED, but not to extensions required for complete QED.

The basic physics disciplines of Maxwell's electrodynamics and Newton's mechanics have been thoroughly tested in the laboratory, but they can nevertheless also support nonphysical solutions. The unphysical nature of some dynamical predictions is demonstrated by the violation of symmetry principles. Symmetries are fundamental in physics since they establish conservation principles. The procedures explored here involve gauge transformations that alter basic symmetries, and these alterations are possible because gauge transformations are not necessarily unitary despite the widespread assumption that they are. That gauge transformations can change the fundamental physical meaning of a problem despite the preservation of electric and magnetic fields is a universal proof that potentials are more basic than fields. These conclusions go to the heart of physics. Problems are not evident when fields are perturbatively weak, but the properties demonstrated here can be critical in strong-field physics where the electromagnetic potential becomes the dominant influence in interactions with matter.

In a decade-and-a-half old experiment, Raabe et al.(Nature 431 (2004) 823), had studied fusion of an incoming beam of halo nucleus 6 He with the target nucleus 238 U . We extract a new interpretation of the experiment, different from the one that has been inferred so far. We show that their experiment is actually able to discriminate between the structures of the target nucleus (behaving as standard nucleus with density distribution described with canonical RMS radius r = r 0 A 1 3 with r 0 = 1.2 fm), and the {\bf "core"} of the halo nucleus, which surprisingly, does not follow the standard density distribution with the above RMS radius. In fact the core has the structure of a tennis-ball (bubble) like nucleus, with a "hole" at the centre of the density distribution. This novel interpretation of the fusion experiment provides an unambigous support to an almost two decades old model (Abbas, Mod. Phys. Lett. A 16 (2001) 755), of the halo nuclei. This Quantum Chromodyanamics based model, succeeds in identifyng all known halo nuclei and makes clear-cut and unique predictions for new and heavier halo nuclei. This model supports the existence of tennis-ball (bubble) like core, of even the giant-neutron halo nuclei. This should prove beneficial to the experimentalists, to go forward more confidently, in their study of exotic nuclei.