Skip to main content

The Big-Bang Theory

This image represents the evolution of the Universe, starting with the Big Bang. The red arrow marks the flow of time. Credit: NASA


Over the past century, rooted in the theory of general relativity, cosmology has developed a very successful physical model of the universe: the big-bang model. Its construction followed different stages to incorporate nuclear processes, the understanding of the matter present in the universe, a description of the early universe and of the large scale structure. This model has been confronted to a variety of observations that allow one to reconstruct its expansion history, its thermal history and the structuration of matter. Hence, what we refer to as the big-bang model today is radically different from what one may have had in mind a century ago. This construction changed our vision of the universe, both on observable scales and for the universe as a whole. It offers in particular physical models for the origins of the atomic nuclei, of matter and of the large scale structure.

In a recent text (Jean-Philippe Uzan 2016) the author summarizes the main steps of the construction of the model, linking its main predictions to the observations that back them up. It also discusses its weaknesses, the open questions and problems, among which the need for a dark sector including dark matter and dark energy.

Links

Etichette:

Comments

Post a Comment

Popular posts from this blog

Astrophysics collection (March 11, 2016)

Latest astrophysics news Rotation curves of galaxies as a test of MOND? Galaxies are rotating with such speed that the gravity generated by their observable matter could not possibly hold them together. In a recent paper ( Haghi et al. 2016 ) the authors test the Modified Newtonian Dynamics (MOND).    Read>> A binary origin for a central compact object (CCO)? Doroshenko et al. 2016 investigate the possible binary origin of the CCO XMMUJ173203.3-344518 .   Read>> Rapidly rotating pulsars as possible sources of fast radio bursts (FRB) In a recent paper ( Lyutikov et al. 2016 ) the authors discuss possible association of fast radio bursts (FRBs) with supergiant pulses emitted by young pulsars.   Read>> Supernovae from WD-WD direct collisions In recent years it was suggested that WD-WD direct collisions (probably extremely rare and occurring only in dense stellar clusters) provide an additional channel for supernova...
Post a Comment
Read more

Dark Neutron Stars

Illustration of a neutron star. Credit: NASA/Dana Berry There is good evidence that electron-positron pair formation is not present in that section of the pulsar open magnetosphere which is the source of coherent radio emission, but the possibility of two-photon pair creation in an outer gap remains. Calculation of transition rates for this process based on measured whole-surface temperatures, combined with a survey of gamma-ray, X-ray and optical luminosities, expressed per primary beam lepton, shows that few Fermi LAT pulsars have significant outer-gap pair creation. For radio-loud pulsars with positive polar-cap corotational charge density and an ion-proton plasma there must be an outward flow of electrons from some other part of the magnetosphere to maintain a constant net charge on the star. In the absence of pair creation, it is likely that this current is the source of GeV gamma-emission observed by the Fermi LAT and its origin is in the region of the outer gap. With n...
Post a Comment
Read more

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).
Post a Comment
Read more