689 research outputs found
Dark energy density predicted and explained
It has recently been shown that the observed Hubble function for cosmological
expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with
only one free constant, while neglecting cosmic curvature and mass, using the
modified Friedmann equation implied by subjecting the Higgs scalar field model
to conformal Weyl scaling symmetry. Time-dependent solutions of the
relativistic conformal Higgs scalar field equation coupled with the conformal
Friedmann equation are shown here to imply dark energy of the observed
magnitude. Predicted persistent cosmic acceleration is consistent with the
nonclassical parameter inferred by conformal theory from observed excessive
galactic rotation velocities and galactic dark halos, all without dark matter.Comment: 6 pages MS revised abstract, text, and references. Accepted for
Europhysics Letter
Conformal theory of gravitation and cosmology
The postulate of universal local Weyl scaling (conformal) symmetry modifies
both general relativity and the Higgs scalar field model. Conformal gravity
(CG) has recently been fitted to rotation data for 138 galaxies. The conformal
Higgs model (CHM) acquires a gravitational effect that fits observed Hubble
expansion for redshifts (7.33 Gyr) accurately with only one free
constant parameter. The astrophysical data fitted by these two conformal models
is shown here to account for both arbitrary parameters and of
postulated Higgs potential ,
responsible for symmetry-breaking finite in electroweak
particle theory. The present analysis resolves recent criticism of CG. CG and
CHM are shown here to be interdependent but compatible. Nonclassical CG
acceleration is shown to be determined by the CHM. Conformal theory
explains dark energy and does not require dark matter, a viable alternative to
the CDM standard model. A recently established empirical relationship
between classical and nonclassical galactic radial acceleration requires
parameter to be independent of galactic mass. Conformal theory is
shown here to be consistent with this and with the baryonic Tully-Fisher
relation for galactic rotation velocities. Vanishing of centripetal
acceleration outside a halo boundary is a unique implication of the theory.Comment: 7 pages accepted for publication by EuroPhysLet
Dark galactic halos without dark matter
Using standard Einstein theory, baryonic mass cannot account for observed
galactic rotation velocities and gravitational lensing, attributed to galactic
dark matter halos. In contrast, theory constrained by Weyl conformal scaling
symmetry explains observed galactic rotation in the halo region without
invoking dark matter. An explanation of dark halos, gravitational lensing, and
structural stabilization, without dark matter and consistent with conformal
theory, is proposed here. Condensation of uniform primordial matter into a
material cloud or galaxy vacates a large surrounding spherical halo. Within
such an extended vacancy in the original cosmic background mass-energy density,
conformal theory predicts centripetal acceleration of the observed magnitude.Comment: 5 pages, updated text, recent references added, accepted for
Europhysics Letter
Conformal Gravity: Dark Matter and Dark Energy
This short review examines recent progress in understanding dark matter, dark
energy, and galactic halos using theory that departs minimally from standard
particle physics and cosmology. Strict conformal symmetry (local Weyl scaling
covariance), postulated for all elementary massless fields, retains standard
fermion and gauge boson theory but modifies Einstein-Hilbert general relativity
and the Higgs scalar field model, with no new physical fields. Subgalactic
phenomenology is retained. Without invoking dark matter, conformal gravity and
a conformal Higgs model fit empirical data on galactic rotational velocities,
galactic halos, and Hubble expansion including dark energy.Comment: 9 pp in revtex format. References added with minor text revision
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