Search results
Results From The WOW.Com Content Network
The mass of the observable universe is often quoted as 10 53 kg. [48] In this context, mass refers to ordinary (baryonic) matter and includes the interstellar medium (ISM) and the intergalactic medium (IGM). However, it excludes dark matter and dark energy. This quoted value for the mass of ordinary matter in the universe can be estimated based ...
Although the distance traveled by light from the edge of the observable universe is close to the age of the universe times the speed of light, 13.8 billion light-years (4.2 × 10 ^ 9 pc), the proper distance is larger because the edge of the observable universe and the Earth have since moved further apart. [52]
Historically, different people have suggested various locations as the center of the Universe. Many mythological cosmologies included an axis mundi, the central axis of a flat Earth that connects the Earth, heavens, and other realms together. In the 4th century BC Greece, philosophers developed the geocentric model, based on astronomical ...
The history of the universe after inflation but before a time of about 1 second is largely unknown. [26] However, the universe is known to have been dominated by ultrarelativistic Standard Model particles, conventionally called radiation, by the time of neutrino decoupling at about 1 second. [27]
But the mass density of the universe can be measured from its gravitational clustering, and is found to have only about 30% of the critical density. [13] Since theory suggests that dark energy does not cluster in the usual way it is the best explanation for the "missing" energy density.
The Earth and Moon are much closer to being a binary planet; the center of mass around which they both rotate is still inside the Earth, but is about 4,624 km (2,873 miles) or 72.6% of the Earth's radius away from the centre of the Earth (thus closer to the surface than the center).
Knowledge of the location of Earth has been shaped by 400 years of telescopic observations, and has expanded radically since the start of the 20th century. Initially, Earth was believed to be the center of the Universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. [1]
Gravitational energy from visible matter accounts for 26–37% of the observed total mass–energy density. [15] Therefore, to fit the concept of a "zero-energy universe" to the observed universe, other negative energy reservoirs besides gravity from baryonic matter are necessary. These reservoirs are frequently assumed to be dark matter. [16]