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The Big Bang model states that the earliest state of the universe was an extremely hot and dense one, and that the universe subsequently expanded and cooled. The model is based on general relativity and on simplifying assumptions such as the homogeneity and isotropy of space.
The universe's size is unknown, and it may be infinite in extent. Some parts of the universe are too far away for the light emitted since the Big Bang to have had enough time to reach Earth or space-based instruments, and therefore lie outside the observable universe. In the future, light from distant galaxies will have had more time to travel ...
e. In physical cosmology, the shape of the universe refers to both its local and global geometry. Local geometry is defined primarily by its curvature, while the global geometry is characterised by its topology (which itself is constrained by curvature). General relativity explains how spatial curvature (local geometry) is constrained by gravity.
The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] It was first proposed as a physical theory in 1931 by Roman Catholic priest and physicist Georges Lemaître when he suggested the universe emerged from a "primeval atom". Various cosmological models of the Big ...
Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the radius of the Sun (approximately 695,700 km; 432,300 mi ). [1] The Sun, the orbit of Earth, Jupiter, and Neptune, compared to four stars.
The chronology of the universedescribes the history and future of the universeaccording to Big Bangcosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion yearsago, with an uncertaintyof around 21 million years at the 68% confidence level.
In physical cosmology, the age of the universe is the time elapsed since the Big Bang.Astronomers have derived two different measurements of the age of the universe: a measurement based on direct observations of an early state of the universe, which indicate an age of 13.787 ± 0.020 billion years as interpreted with the Lambda-CDM concordance model as of 2021; and a measurement based on the ...
The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. [1] It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it. To any observer in the universe, it appears that all but the nearest galaxies ...