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Since the universe is expanding, the equation for that expansion can be "run backwards" to its starting point. The Lambda-CDM concordance model describes the expansion of the universe from a very uniform, hot, dense primordial state to its present state over a span of about 13.77 billion years [12] of cosmological time.
An important parameter in fate of the universe theory is the density parameter, omega (), defined as the average matter density of the universe divided by a critical value of that density. This selects one of three possible geometries depending on whether Ω {\displaystyle \Omega } is equal to, less than, or greater than 1 {\displaystyle 1} .
Given our assumed half-life of the proton, nucleons (protons and bound neutrons) will have undergone roughly 1,000 half-lives by the time the universe is 10 43 years old. This means that there will be roughly 0.5 1,000 (approximately 10 −301 ) as many nucleons; as there are an estimated 10 80 protons currently in the universe, [ 41 ] none ...
The theory suggests that from the "Big Bang" through the present day, matter and dark matter in the universe are thought to have been concentrated in stars, galaxies, and galaxy clusters, and are presumed to continue to do so well into the future. Therefore, the universe is not in thermodynamic equilibrium, and objects can do physical work.
List of other end scenarios than Heat Death – Theories about the end of the universe; Tiny Graphical timeline from Big Bang to Heat Death – Future scenario in which the expansion of the universe continues forever - Timeline uses the log scale for comparison with the double-logarithmic scale in this article.
The estimated time for all nucleons in the observable universe to decay, if the hypothesized proton half-life takes the largest possible value of 10 41 years, [9] assuming that the Big Bang was inflationary and that the same process that made baryons predominate over anti-baryons in the early universe makes protons decay.
The problem was that at various times in the 20th century, the universe was estimated to be younger than the oldest observed stars. Estimates of the universe's age came from measurements of the current expansion rate of the universe, the Hubble constant H 0 {\displaystyle H_{0}} , as well as cosmological models relating H 0 {\displaystyle H_{0 ...
The chronology of the universe describes the history and future of the universe according to Big Bang cosmology.. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, with an uncertainty of around 21 million years at the 68% confidence level.