Search results
Results From The WOW.Com Content Network
A cosmological phase transition is an overall change in the state of matter across the whole universe. The success of the Big Bang model led researchers to conjecture possible cosmological phase transitions taking place in the very early universe, at a time when it was much hotter and denser than today.
A sample of 229 nearby "thick" disk stars has been used to investigate the existence of an age-metallicity relation in the Galactic thick disk and indicates that there is an age-metallicity relation present in the thick disk. [13] [14] Stellar ages from asteroseismology confirm the lack of any strong age-metallicity relation in the Galactic ...
A prominent example in this context is inhomogeneous cosmology, to model the observed accelerating universe and cosmological constant. Instead of using the current accepted idea of dark energy , this model proposes the universe is much more inhomogeneous than currently assumed, and instead, we are in an extremely large low-density void. [ 31 ]
Without major changes to the Big Bang theory itself, BBN will result in mass abundances of about 75% of hydrogen-1, about 25% helium-4, about 0.01% of deuterium and helium-3, trace amounts (on the order of 10 −10) of lithium, and negligible heavier elements. That the observed abundances in the universe are generally consistent with these ...
[73]: 245 As an example of the fine-tuning issue, standard cosmology cannot predict the present temperature of the relic radiation, . [ 73 ] : 229 This value of T 0 {\displaystyle T_{0}} is one of the best results of experimental cosmology and the steady state model can predict it. [ 61 ]
Some examples are quintessence, a proposed form of dark energy with a non-constant state equation, whose density decreases with time. A negative mass cosmology does not assume that the mass density of the universe is positive (as is done in supernova observations), and instead finds a negative cosmological constant.
In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course ...
The local geometry of the universe is determined by whether the relative density Ω is less than, equal to or greater than 1. From top to bottom: a spherical universe with greater than critical density (Ω>1, k>0); a hyperbolic, underdense universe (Ω<1, k<0); and a flat universe with exactly the critical density (Ω=1, k=0).