How do we know that the CMB photons originate in the early universe? We discuss the possibility of their origin from mirror neutrino annihilation and suggest an experimental test of this hypothesis. This essay was not written for any competition on the subject of gravity. Despite its remarkable success, it should be noted that the standard ΛCDM cosmology is largely an empirical affair, with no ...

The modified Newtonian dynamics (MOND), suggested by Milgrom as an alternative to dark matter, implies that isothermal spheres with a fixed anisotropy parameter should exhibit a near perfect relation between the mass and velocity dispersion of the form M ∝ σ. This is consistent with the observed Faber-Jackson relation for elliptical galaxies. However, the observable global properties of ellipti...

The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Supersymmetric phenomenology has been largely bound to the hypothesis that supersymmetry breaking originates from a single source. In this paper, we relax this underlying assumption and consider a multiplicity of sectors which independently break supersymmetry, thus yielding a ...

1550-7998=20 Braneworld cosmology supported by a bulk scalar field with an exponential potential is developed. A general class of separable backgrounds for both single and two-brane systems is derived, where the bulk metric components are given by products of world volume and bulk coordinates and the world-volumes represent any anisotropic and inhomogeneous solution to an effective four-dimensi...

A framework is suggested in which the energy integrals of the Friedmann cosmology are identified as genuine time-independent physical characteristics for both vacuum and non-vacuum forms of cosmic energy. The integrals are found to be numerically coincident within two orders of magnitude. It is assumed that this coincidence reveals a symmetry that relates vacuum to non-vacuum forms of cosmic en...

In the redshift range 100 ,(1+z) ,137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100 °C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standardΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshift...

In this paper we study cosmological application of holographic dark energy density in the Brans-Dicke framwork. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L. Our calculation show, taking Ω Λ = 0.73 for the present time, the ...

We suggest that experiments based on Josephson junctions, SQUIDS, and coupled Josephson qubits may be used to construct a resonant environment for dark matter axions. We propose experimental setups in which axionic interaction strengths in a Josephson junction environment can be tested, similar in nature to recent experiments that test for quantum entanglement of two coupled Josephson qubits. W...

We explore the possibility that the present stage of accelerated expansion of the universe is due to the presence of a cosmic vector field. We show that vector theories allow for the generation of an accelerated phase without the introduction of potential terms or unnatural scales in the Lagrangian. We propose a particular model with the same number of parameters as ΛCDM and excellent fits to S...

These lectures present a brief review of inflationary cosmology, provide an overview of the theory of cosmological perturbations, and then focus on the conceptual problems of the current paradigm of early universe cosmology, thus motivating an exploration of the potential of string theory to provide a new paradigm. Specifically, the string gas cosmology model is introduced, and a resulting mech...