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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 ...
Objects at this stage are known as Class I protostars, [16] which are also called young T Tauri stars, evolved protostars, or young stellar objects. [16] By this time the forming star has already accreted much of its mass: the total mass of the disk and remaining envelope does not exceed 10–20% of the mass of the central YSO.
This action corresponds to the potential [7] [8] = (/ /) in the Einstein frame. As a result, the inflationary scenario associated to this potential or to an action including an term are referred to as Starobinsky inflation. To distinguish, models using the original, more complete, quantum effective action are then called (trace)-anomaly induced ...
The standard model of cosmology, the Lambda-CDM model, assumes the Copernican principle and the more general cosmological principle. Some cosmologists and theoretical physicists have created models without the cosmological or Copernican principles to constrain the values of observational results, to address specific known issues in the Lambda ...
In cosmology, the steady-state model or steady-state theory is an alternative to the Big Bang theory. In the steady-state model, the density of matter in the expanding universe remains unchanged due to a continuous creation of matter, thus adhering to the perfect cosmological principle , a principle that says that the observable universe is ...
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model , or simply cosmology , provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin , structure, evolution , and ultimate fate . [ 1 ]
[3]: 62 The basic model makes two simplifying assumptions: until the temperature drops below 0.1 MeV only neutrons and protons are stable and; only isotopes of hydrogen and of helium will be produced at the end. These assumptions are based on the intense flux of high energy photons in the plasma.
An important feature of loop quantum cosmology is the effective space-time description of the underlying quantum evolution. [10] The effective dynamics approach has been extensively used in loop quantum cosmology to describe physics at the Planck scale and the very early universe.