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  2. Hubble's law - Wikipedia

    en.wikipedia.org/wiki/Hubble's_law

    The Hubble length or Hubble distance is a unit of distance in cosmology, defined as cH −1 — the speed of light multiplied by the Hubble time. It is equivalent to 4,420 million parsecs or 14.4 billion light years. (The numerical value of the Hubble length in light years is, by definition, equal to that of the Hubble time in years.)

  3. 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 ...

  4. Distance measure - Wikipedia

    en.wikipedia.org/wiki/Distance_measure

    Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to another quantity that is ...

  5. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    Edwin Hubble observed that fainter galaxies are more redshifted. Finding the value of the Hubble constant was the result of decades of work by many astronomers, both in amassing the measurements of galaxy redshifts and in calibrating the steps of the distance ladder.

  6. List of unsolved problems in astronomy - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Do early dark energy models resolve the Hubble tension? [25] [32] Baryon asymmetry: Why is there far more matter than antimatter in the observable universe? Cosmological constant problem: Why does the zero-point energy of the vacuum not cause a large cosmological constant? [33] [34] Size and shape of the universe:

  7. Observational cosmology - Wikipedia

    en.wikipedia.org/wiki/Observational_cosmology

    Two years later, Hubble showed that the relation between the distances and velocities was a positive correlation and had a slope of about 500 km/s/Mpc. [10] This correlation would come to be known as Hubble's law and would serve as the observational foundation for the expanding universe theories on which cosmology is still based.

  8. Mini-Hubble will scan dim stars to see if they can support life

    www.aol.com/news/2018-01-11-cubesat-sparcs-scan...

    The aim is to find so-called M Dwarfs, stars 20 times dimmer than our sun, and see if they emit too much radiation to support life on other worlds. Mini-Hubble will scan dim stars to see if they ...

  9. Hubble volume - Wikipedia

    en.wikipedia.org/wiki/Hubble_volume

    The Hubble length / is 14.4 billion light years in the standard cosmological model, equivalent to times Hubble time. The Hubble time is the reciprocal of the Hubble constant, [ 5 ] and is slightly larger than the age of the universe (13.8 billion years) as it is the age the universe would have had if expansion was linear.