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Lithium is also found in brown dwarf substellar objects and certain anomalous metal-poor stars. Because lithium is present in cooler, less massive brown dwarfs, but is destroyed in hotter red dwarf stars, its presence in the stars' spectra can be used in the "lithium test" to differentiate the two, as both are smaller than the Sun. [12] [13] [15]
Big Bang nucleosynthesis predicts a primordial abundance of about 25% helium-4 by mass, irrespective of the initial conditions of the universe. As long as the universe was hot enough for protons and neutrons to transform into each other easily, their ratio, determined solely by their relative masses, was about 1 neutron to 7 protons (allowing ...
A graphical view of the Cosmic Calendar, featuring the months of the year, days of December, the final minute, and the final second. The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its currently understood age of 13.8 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science.
The third most common use of lithium is in greases. Lithium hydroxide is a strong base, and when heated with a fat, it produces a soap, such as lithium stearate from stearic acid. Lithium soap has the ability to thicken oils, and it is used to manufacture all-purpose, high-temperature lubricating greases. [21] [162] [163]
Timeline of the expansion of the universe, where space, including hypothetical non-observable portions of the universe, is represented at each time by the circular sections. On the left, the dramatic expansion occurs in the inflationary epoch ; and at the center, the expansion accelerates (artist's concept; neither time nor size are to scale).
Lithium burning is a nucleosynthetic process in which lithium is depleted in a star. Lithium is generally present in brown dwarfs and not in older low-mass stars. Stars, which by definition must achieve the high temperature (2.5 × 10 6 K) necessary for fusing hydrogen , rapidly deplete their lithium.
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.
This future history and the timeline below assume the continued expansion of the universe. If space in the universe begins to contract, subsequent events in the timeline may not occur because the Big Crunch, the collapse of the universe into a hot, dense state similar to that after the Big Bang, will prevail. [14] [15]