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  2. Expansion of the universe - Wikipedia

    en.wikipedia.org/wiki/Expansion_of_the_universe

    For example, galaxies that are farther than the Hubble radius, approximately 4.5 gigaparsecs or 14.7 billion light-years, away from us have a recession speed that is faster than the speed of light. Visibility of these objects depends on the exact expansion history of the universe.

  3. Accelerating expansion of the universe - Wikipedia

    en.wikipedia.org/wiki/Accelerating_expansion_of...

    For supernovae at redshift less than around 0.1, or light travel time less than 10 percent of the age of the universe, this gives a nearly linear distance–redshift relation due to Hubble's law. At larger distances, since the expansion rate of the universe has changed over time, the distance-redshift relation deviates from linearity, and this ...

  4. Cosmological horizon - Wikipedia

    en.wikipedia.org/wiki/Cosmological_horizon

    Hubble radius, Hubble sphere (not to be confused with a Hubble bubble), Hubble volume, or Hubble horizon is a conceptual horizon defining the boundary between particles that are moving slower and faster than the speed of light relative to an observer at one given time. Note that this does not mean the particle is unobservable; the light from ...

  5. Sonic boom - Wikipedia

    en.wikipedia.org/wiki/Sonic_boom

    The cracking sound a bullwhip makes when properly wielded is, in fact, a small sonic boom. The end of the whip, known as the "cracker", moves faster than the speed of sound, thus creating a sonic boom. [2] A bullwhip tapers down from the handle section to the cracker. The cracker has much less mass than the handle section.

  6. Future of an expanding universe - Wikipedia

    en.wikipedia.org/wiki/Future_of_an_expanding...

    If dark energy—represented by the cosmological constant, a constant energy density filling space homogeneously, [3] or scalar fields, such as quintessence or moduli, dynamic quantities whose energy density can vary in time and space—accelerates the expansion of the universe, then the space between clusters of galaxies will grow at an ...

  7. Cosmic inflation - Wikipedia

    en.wikipedia.org/wiki/Cosmic_inflation

    As the inflationary field slowly relaxes to the vacuum, the cosmological constant goes to zero and space begins to expand normally. The new regions that come into view during the normal expansion phase are exactly the same regions that were pushed out of the horizon during inflation, and so they are at nearly the same temperature and curvature ...

  8. Time dilation - Wikipedia

    en.wikipedia.org/wiki/Time_dilation

    Also, a climber's time is theoretically passing slightly faster at the top of a mountain compared to people at sea level. It has also been calculated that due to time dilation, the core of the Earth is 2.5 years younger than the crust. [34] "A clock used to time a full rotation of the Earth will measure the day to be approximately an extra 10 ...

  9. Alcubierre drive - Wikipedia

    en.wikipedia.org/wiki/Alcubierre_drive

    The Alcubierre drive ([alkuˈβjere]) is a speculative warp drive idea according to which a spacecraft could achieve apparent faster-than-light travel by contracting space in front of it and expanding space behind it, under the assumption that a configurable energy-density field lower than that of vacuum (that is, negative mass) could be created.