Edwin Hubble

Edwin Powell Hubble (November 20, 1889–September 28, 1953) was an American astronomer, noted for his discovery of galaxies beyond the Milky Way and the cosmological redshift. Edwin Hubble was one of the first to argue that the red shift of distant galaxies is due to the Doppler effect induced by the expansion of the universe. He was one of the leading astronomers of modern times and laid down the foundation upon which physical cosmology now rests.

Contents [hide] 1 Biography 2 Discoveries 2.1 Galaxies exist beyond the Milky Way 2.2 The universe is expanding 2.3 Other discoveries 3 Nobel Prize 4 Honors 5 Footnotes 6 Bibliography 7 External links 8 See also

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Biography

Edwin Hubble was born to an insurance executive in Marshfield, Missouri and moved to Wheaton, Illinois in 1889. In his younger days, he was noted more for his athletic abilities rather than his intellectual genius, although he did earn good grades in every subject, except for spelling. He won seven first places^[1] and a third placing in a single high school meet in 1906. That year he also set a state record for high jump in Illinois.

His studies at the University of Chicago concentrated on mathematics and astronomy which led to a BS degree in 1910. He spent the next three years as one of Oxford's first Rhodes Scholars, where he studied in the field of law and received the MA degree, after which he returned to the United States as a high school teacher and a basketball coach in New Albany, Indiana.

He served in World War I and quickly became Major. He returned to astronomy at the Yerkes Observatory of the University of Chicago, where he earned a PhD in 1917 with a dissertation entitled "Photographic Investigations of Faint Nebulae". In 1919 Hubble was offered a staff position by George Ellery Hale, the founder and director of Carnegie Institution's Mount Wilson Observatory, near Pasadena, California, where he remained until his death. He also served in the US army during World War II. Shortly before his death, Palomar's 200-inch Hale Telescope was completed; Hubble was the first to use it.

He died of a heart attack on September 28, 1953, in San Marino, California. His wife, Grace, did not have a funeral for him and never revealed what was done with his body - it was apparently Hubble's wish to have no funeral service and be buried in an unmarked grave, or that he wanted to be cremated. As of 2006, the whereabouts of his remains are unknown.

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Discoveries

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Galaxies exist beyond the Milky Way

Hubble's arrival at Mount Wilson in 1919 coincided roughly with the completion of the 100-inch Hooker Telescope, then the world's most powerful telescope. Hubble's observations in 1923–1924 with the Hooker Telescope established beyond doubt that the fuzzy "nebulae" seen earlier with less powerful telescopes were not part of our galaxy, as had been thought, but were galaxies themselves, outside the Milky Way. He announced this discovery on December 30, 1924.

Hubble also devised a classification system for galaxies, grouping them according to their content, distance, shape, size and brightness.

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The universe is expanding

The 100 inch Hooker telescope at Mount Wilson Observatory that Hubble used to measure galaxy redshifts and discover the general expansion of the universe.

Hubble was generally incorrectly credited with discovering^[2] the redshift of galaxies. These measurements and their significance were understood before 1917 by James Edward Keeler (Lick & Allegheny), Vesto Melvin Slipher (Lowell), and Professor William Wallace Campbell (Lick) at other observatories. Combining his own measurements of galaxy distances with Vesto Slipher's measurements of the redshifts associated with the galaxies, Hubble and Milton L. Humason discovered a rough proportionality of the objects' distances with their redshifts. Though there was considerable scatter (now known to be due to peculiar velocities), Hubble and Humason were able to plot a trend line from the 46 galaxies they studied and obtained a value for the Hubble-Humason constant of 500 km/s/Mpc, which is much higher than the currently accepted value due to errors in their distance calibrations. Such errors in determining distance continue to plague modern astronomers. See the article on cosmic distance ladder for more details. In 1929 Hubble and Humason formulated the empirical Redshift Distance Law of galaxies, nowadays termed simply Hubble's law, which, if the redshift is interpreted as a measure of recession speed, is consistent with the solutions of Einstein’s General Relativity Equations for an homogeneous, isotropic expanding space de Sitter universe or de Sitter space. Although concepts underlying an expanding universe were well understood earlier, this statement by Hubble and Humeson lead to wider scale acceptance for this view. The law states that the greater the distance between any two galaxies, the greater their relative speed of separation.

This discovery later resulted in formulation of the Big Bang theory by George Gamow, a consequence of the observed velocities of distant galaxies that when taken together with the cosmological principle imply that space is expanding according to the Friedmann-Lemaître model of general relativity.

Earlier, in 1917, Albert Einstein had found that his newly developed General Theory of Relativity indicated that the universe must be either expanding or contracting. Unable to believe what his own equations were telling him, Einstein introduced a cosmological constant (a "fudge factor") to the equations to avoid this "problem". When Einstein heard of Hubble's discovery, he said that changing his equations was "the biggest blunder of my life".^[3]

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Other discoveries

Hubble discovered the asteroid 1373 Cincinnati on August 30, 1935. He also wrote The Observational Approach to Cosmology and The Realm of the Nebulae around this time.

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Nobel Prize

Hubble spent much of the later part of his career attempting to have astronomy considered an area of physics, instead of being its own science. He did this largely so that astronomers - including himself - could be recognized by the Nobel Prize Committee for their valuable contributions to astrophysics. This campaign was long unsuccessful and unfortunately Hubble's great achievements would remain unrewarded. The Nobel Prize Committee eventually decided that astronomical work would be eligable for the physics prize. Unfortunately for Hubble, this occurred in 1953 some months after Hubble's death. The Nobel Prize is never awarded posthumously.

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Honors

Awards

• Bruce Medal in 1938.
• Gold Medal of the Royal Astronomical Society in 1940.
• Medal of Merit for outstanding contribution to ballistics research in 1946--ARP

Named after him

• Asteroid 2069 Hubble.
• Hubble crater on the Moon.
• Orbiting Hubble Space Telescope.

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Footnotes

1. ^ For the record, these were discus, hammer throw, pole vault, standing and running high jump, shot put, mile-relay. The third-placing was for broad jump.^{[citation needed]}
2. ^ This had actually been observed by Vesto Slipher in the 1910s, but the world was largely unaware. Ref: Slipher (1917): Proc. Amer. Phil. Soc., 56, 403.

   The world is also largely unaware that Hubble never believed that his own model of the expanding universe model was the correct one:

   … if redshift are not primarily due to velocity shift … the velocity-distance relation is linear, the distribution of the nebula is uniform, there is no evidence of expansion, no trace of curvature, no restriction of the time scale … and we find ourselves in the presence of one of the principle of nature that is still unknown to us today … whereas, if redshifts are velocity shifts which measure the rate of expansion, the expanding models are definitely inconsistent with the observations that have been made … expanding models are a forced interpretation of the observational results (E. Hubble, Ap. J., 84, 517, 1936.)

   [If the redshifts are a Doppler shift] … the observations as they stand lead to the anomaly of a closed universe, curiously small and dense, and, it may be added, suspiciously young. On the other hand, if redshifts are not Doppler effects, these anomalies disappear and the region observed appears as a small, homogeneous, but insignificant portion of a universe extended indefinitely both in space and time. (Royal Astronomical Society Monthly Notices, 17, 506, 1937).

3. ^ http://www.pbs.org/wnet/hawking/strange/html/strange_cosmo.html

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Bibliography

• Hubble E.P., The Observational Approach to Cosmology (Oxford, 1937).
• Hubble E.P., The Realm of the Nebulae (New Haven, 1936).

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External links

Wikimedia Commons has media related to:

Edwin Powell Hubble

• Time 100 Profile
• Astronomy at the University of Louisville - Photographs of Edwin Hubble at New Albany High School.
• Edwin Hubble bio - Written by Allan Sandage

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See also

• Galaxies
  • Galaxy classification
  • Gerard de Vaucouleurs
  • De Vaucouleurs modified Hubble sequence
  • Hubble sequence
  • Spiral nebula
• Expansion of the universe
  • Big bang
  • Albert Einstein
  • Relativity
  • Hubble's Law
  • Hubble constant
• Hubble Space Telescope