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  2. Age of the universe - Wikipedia

    en.wikipedia.org/wiki/Age_of_the_universe

    The first observation that one can make from this formula is that it is the Hubble parameter that controls that age of the universe, with a correction arising from the matter and energy content. So a rough estimate of the age of the universe comes from the Hubble time, the inverse of the Hubble parameter.

  3. Stellar age estimation - Wikipedia

    en.wikipedia.org/wiki/Stellar_age_estimation

    Various methods and tools are involved in stellar age estimation, an attempt to identify within reasonable degrees of confidence what the age of a star is. These methods include stellar evolutionary models , membership in a given star cluster or system , fitting the star with the standard spectral and luminosity classification system , and the ...

  4. Spacetime - Wikipedia

    en.wikipedia.org/wiki/Spacetime

    Space and Time included the first public presentation of spacetime diagrams (Fig. 1-4), ... [50] so Fig. 3-12b presents instead a graphing calculator solution.

  5. Twin paradox - Wikipedia

    en.wikipedia.org/wiki/Twin_paradox

    In physics, the twin paradox is a thought experiment in special relativity involving twins, one of whom takes a space voyage at relativistic speeds and returns home to find that the twin who remained on Earth has aged more.

  6. List of oldest stars - Wikipedia

    en.wikipedia.org/wiki/List_of_oldest_stars

    The age of the oldest known stars approaches the age of the universe, about 13.8 billion years. Some of these are among the first stars from reionization (the stellar dawn), ending the Dark Ages about 370,000 years after the Big Bang. [1] This list includes stars older than 12 billion years, or about 87% of the age of the universe.

  7. The Five Ages of the Universe - Wikipedia

    en.wikipedia.org/wiki/The_Five_Ages_of_the_Universe

    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.

  8. Space Age - Wikipedia

    en.wikipedia.org/wiki/Space_Age

    The Space Age is a period encompassing the activities related to the space race, space exploration, space technology, and the cultural developments influenced by these events, beginning with the launch of Sputnik 1 on October 4, 1957, [1] and continuing to the present.

  9. Timeline of astronomy - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_astronomy

    The Soviet Union launches the first artificial satellite, Sputnik 1, into orbit, beginning the space age. The US launches its first satellite, Explorer 1, four months later. 1958