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In physical cosmology, the age of the universe is the time elapsed since the Big Bang: 13.8 billion years. [1] Astronomers have two different approaches to determine the age of the universe . One is based on a particle physics model of the early universe called Lambda-CDM , matched to measurements of the distant, and thus old features, like the ...
Since the universe has been expanding for 13.8 billion years, the comoving distance (radius) is now about 46.6 billion light-years. Thus, volume ( 4 / 3 πr 3 ) equals 3.58 × 10 80 m 3 and the mass of ordinary matter equals density ( 4.08 × 10 −28 kg/m 3 ) times volume ( 3.58 × 10 80 m 3 ) or 1.46 × 10 53 kg .
The universe has appeared much the same as it does now, for many billions of years. It will continue to look similar for many more billions of years into the future. The galactic disk of the Milky Way is estimated to have been formed 8.8 ± 1.7 billion years ago but only the age of the Sun, 4.567 billion years, is known precisely. [69]
It is expected to detect stars in the early Universe approximately 280 million years older than stars HST now detects. [275] The telescope is an international collaboration between NASA, the European Space Agency, and the Canadian Space Agency since 1996, [ 276 ] and was launched on December 25, 2021, on an Ariane 5 rocket. [ 277 ]
The observable universe contains as many as an estimated 2 trillion galaxies [95] [96] [97] and, overall, as many as an estimated 10 24 stars [98] [99] – more stars (and earth-like planets) than all the grains of beach sand on planet Earth; [100] [101] [102] but less than the total number of atoms estimated in the universe as 10 82; [103] and ...
With the release of Gaia's observations of the star, it has since been refined to a much closer 0.178 light-years (0.055 pc), close enough to significantly disturb objects in the Oort cloud, which extends 1.2 light-years (0.37 pc) from the Sun. [74] Gaia 's third data release has provided updated values for many of the candidates in the table ...
This would be equivalent to expanding an object 1 nanometer across (10 −9 m, about half the width of a molecule of DNA) to one approximately 10.6 light-years across (about 10 17 m, or 62 trillion miles).
According to the Big Bang theory, the very early universe was an extremely hot and dense state about 13.8 billion years ago [21] which rapidly expanded. About 380,000 years later the universe had cooled sufficiently to allow protons and electrons to combine and form hydrogen—the so-called recombination epoch.