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  2. Chronology of the universe - Wikipedia

    en.wikipedia.org/wiki/Chronology_of_the_universe

    The thin disk of our galaxy began to form at about 5 billion years (8.8 Gya), [12] and the Solar System formed at about 9.2 billion years (4.6 Gya), with the earliest evidence of life on Earth emerging by about 10 billion years (3.8 Gya).

  3. Purple Earth hypothesis - Wikipedia

    en.wikipedia.org/wiki/Purple_Earth_hypothesis

    The Purple Earth Hypothesis (PEH) is an astrobiological hypothesis, first proposed by molecular biologist Shiladitya DasSarma in 2007, [1] that the earliest photosynthetic life forms of Early Earth were based on the simpler molecule retinal rather than the more complex porphyrin-based chlorophyll, making the surface biosphere appear purplish ...

  4. Galaxy formation and evolution - Wikipedia

    en.wikipedia.org/wiki/Galaxy_formation_and_evolution

    The Lambda-CDM model is a cosmological model that explains the formation of the universe after the Big Bang. It is a relatively simple model that predicts many properties observed in the universe, including the relative frequency of different galaxy types; however, it underestimates the number of thin disk galaxies in the universe. [5]

  5. Timeline of cosmological theories - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_cosmological...

    c. 16th century BCE – Mesopotamian cosmology has a flat, circular Earth enclosed in a cosmic ocean. [1]c. 15th–11th century BCE – The Rigveda of Hinduism has some cosmological hymns, particularly in the late book 10, notably the Nasadiya Sukta which describes the origin of the universe, originating from the monistic Hiranyagarbha or "Golden Egg".

  6. Timeline of the early universe - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_the_early_universe

    c. 10 −43 seconds: Grand unification epoch begins: While still at an infinitesimal size, the universe cools down to 10 32 kelvin. Gravity separates and begins operating on the universe—the remaining fundamental forces stabilize into the electronuclear force, also known as the Grand Unified Force or Grand Unified Theory (GUT), mediated by (the hypothetical) X and Y bosons which allow early ...

  7. What reionized the Universe, and when? - AOL

    www.aol.com/news/reionized-universe-130013955.html

    When did the Universe first become transparent? It’s a weird question, but an important one. The Universe started off opaque, but became transparent some time after, and remains that way even today.

  8. Universe - Wikipedia

    en.wikipedia.org/wiki/Universe

    Although the distance traveled by light from the edge of the observable universe is close to the age of the universe times the speed of light, 13.8 billion light-years (4.2 × 10 ^ 9 pc), the proper distance is larger because the edge of the observable universe and the Earth have since moved further apart. [52]

  9. Cosmic Calendar - Wikipedia

    en.wikipedia.org/wiki/Cosmic_Calendar

    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.