Five+Ages+Of+The+Universe+book

=Five Ages Of The Universe book=

toc Read here about a book that addresses issues of scale.

=Overview=

The Five Ages Of The Universe is a popular science book written by Fred Adams and Gregory Laughlin, first published in 1999. In that book cosmological decades follow in logarithmic order from the primordial era, through the stelliferous, degenerate, black hole, and today the dark era.

=The Ages= From wikipedia :

The time scales treated in the book are sufficiently vast that the authors find it convenient to use scientific notation. They refer to the "nth cosmological decade," meaning 10n years after the big bang. In what follows, n refers to the cosmological decade.

Primordial Era
The Primordial Era is defined as "-50 < n < 5". In this era, the Big Bang, the subsequent inflation, and Big Bang nucleosynthesis are thought to have taken place. Toward the end of this age, the recombination of electrons with nuclei made the universe transparent for the first time. The authors discuss the horizon and flatness problems.

Stelliferous Era
The Stelliferous Era is defined as "6 < n < 14". This is the current era, in which matter is arranged in the form of stars, galaxies, and galaxy clusters, and most energy is produced in stars. Massive stars use up their fuel very rapidly, in as little as a few million years. Eventually, the only stars will be miserly red dwarf stars. By the end of this era, bright stars as we know them will be gone, their nuclear fuel exhausted, and only white dwarfs, brown dwarfs, and black holes will remain. In this section, Olbers' paradox is discussed.

Degenerate Era
The Degenerate Era is defined as "15 < n < 39".This is the era of brown dwarfs, white dwarfs, and black holes. White dwarfs will assimilate dark matter and continue with a nominal energy output. As this era continues, the authors hypothesize that protons will begin to decay (violating the conservation of baryon number given by the Standard Model). If proton decay takes place, the sole survivors will be black holes.

Black Hole Era
The Black Hole Era is defined as "40 < n < 100". In this era, according to the book, organized matter will remain only in the form of black holes. Black holes themselves slowly "evaporate" away the matter contained in them, by the quantum mechanical process of Hawking radiation. By the end of this era, only extremely low-energy photons, electrons, positrons, and neutrinos will remain.

Dark Era
The Dark Era is defined as "n > 101". By this era, with only very diffuse matter remaining, activity in the universe will have tailed off dramatically, with very low energy levels and very large time scales. Electrons and positrons drifting through space will encounter one another and occasionally form positronium atoms. These structures are unstable, however, and their constituent particles must eventually annihilate. Other low-level annihilation events will also take place, albeit very slowly.

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