future

The  Big Crunch  is a hypothetical scenario for the ultimate fate of the universe  , in which the expansion of the universe   eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor   to reach zero, an event potentially followed by a reformation of the universe starting with another Big bang  . The vast majority of evidence indicates that this theory is not correct. Instead, astronomical observations show that the expansion of the universe is accelerating  , rather than being slowed by gravity , suggesting that the universe is far more likely to end in heat death  or a Big Rip . The Big Crunch scenario hypothesized that the density of matter throughout the universe is sufficiently high that gravitational attraction will overcome the expansion which began with the Big Bang. The FLRW   cosmology  can predict whether the expansion will eventually sto...

  The   Andromeda Galaxy   , also known as   Messier 31 ,   M31 , or   NGC 224   and originally the   Andromeda Nebula   (see below), is a  Barred spiral galaxy    approximately 2.5 million  light-years   (770  Kiloparsecs ) from Earth and the nearest large galaxy to the  Milky way .   The galaxy's name stems from the area of Earth's sky in which it appears, the Constellation of Andromeda    , which itself is named after the  Ethiopian (or Phoenicia)   who was the wife of  Perseus in Greek mythology  .  The virial masses of the Andromeda Galaxy is of the same order of magnitude as that of the Milky Way, at 1 trillion solar masses (2.0 × 10 42  kilograms). The mass of either galaxy is difficult to estimate with any accuracy, but it was long thought that the Andromeda Galaxy is more massive than the Milky Way by a margin of some 25% to 50%. This has been called...

 Plutarch 's  Lives of the Noble Greeks and Romans , commonly called  Parallel Lives  or  Plutarch's Lives , is a series of 48 biographies of famous men, arranged in pairs to illuminate their common moral virtues or failings, probably written at the beginning of the second century AD.   The surviving  Parallel Lives  (Greek : Βίοι Παράλληλοι,  Bíoi Parállēloi ) comprises 23 pairs of biographies, each pair consisting of one Greek  and one Roman  of similar destiny, such as Alexander the great   and Julius caesar , or Demosthenes  and Cicero . It is a work of considerable importance, not only as a source of information about the individuals described, but also about the times in which they lived. Parallel Lives  was Plutarch's second set of biographical works, following the Lives of the Roman Emperors from Augustus  to Vitellius . Of these, only the Lives of Galba and Otho survive.  As he e...

  A   nebula   (Latin   for 'cloud' or 'fog';   pl.   nebulae ,   nebulæ   or   nebulas ) is a distinct body of  interstellar clouds   (which can consist of    cosmic dust, hydrogen , helium , molecular clouds ; possibly as  ionized gases ). Originally, the term was used to describe any diffused  astronomical object  , including  galaxies    beyond the  Milky  Way . The  Andromeda Galaxy  , for instance, was once referred to as the   Andromeda Nebula   (and     spiral galaxies  in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by vesto slipher, Edwin Hubble    and others. Edwin Hubble discovered that most nebulae are associated with stars and illuminated by starlight. He also helped categorize nebulae based on the type of light spectra they produced. Most nebulae are of vast size; so...