Search results
Results From The WOW.Com Content Network
LNH was Dirac's personal response to a set of large number "coincidences" that had intrigued other theorists of his time. The "coincidences" began with Hermann Weyl (1919), [2] [3] who speculated that the observed radius of the universe, R U, might also be the hypothetical radius of a particle whose rest energy is equal to the gravitational self-energy of the electron:
This metric has only two undetermined parameters. An overall dimensionless length scale factor R describes the size scale of the universe as a function of time (an increase in R is the expansion of the universe), [152] and a curvature index k describes the geometry.
These equations specify the evolution of the scale factor the universe in terms of the pressure and density of a perfect fluid. The evolving density is composed of different kinds of energy and matter, each with its own role in affecting the scale factor. [4]: 7 For example, a model might include baryons, photons, neutrinos, and dark matter.
Planck length; typical scale of hypothetical loop quantum gravity or size of a hypothetical string and of branes; according to string theory, lengths smaller than this do not make any physical sense. [1] Quantum foam is thought to exist at this scale. 10 −24: 1 yoctometer 142 ym Effective cross section radius of 1 MeV neutrinos [2] 10 −21
This theory of rapid spatial expansion gave an explanation for large-scale isotropy by allowing causal connection just before the epoch of last scattering. [33]: 8.5.4 With this and similar theories, detailed prediction encouraged larger and more ambitious experiments.
It represents the boundary between the observable and the unobservable regions of the universe, so its distance at the present epoch defines the size of the observable universe. Due to the expansion of the universe, it is not simply the age of the universe times the speed of light, as in the Hubble horizon, but rather the speed of light ...
The findings announced on Tuesday are part of a years-long study of the history of the cosmos focusing upon dark energy, an invisible and enigmatic force that is accelerating the ongoing expansion ...
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The concept of an expanding universe was scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.