Everything about Edwin Hubble totally explained
Edwin Powell Hubble (
November 20,
1889 –
September 28,
1953) was an
American astronomer. He profoundly changed astronomers' understanding of the nature of the universe by demonstrating the existence of other galaxies besides the
Milky Way. He also discovered that the degree of redshift observed in light coming from a galaxy increased in proportion to the distance of that galaxy from the Milky Way. This became known as
Hubble's law, and would help establish that the universe is expanding.
Biography
He 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 prowess than his intellectual abilities, although he did earn good grades in every subject except for spelling. He won seven first places and a third place in a single high school track 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, astronomy, and philosophy which led to a
BS degree in 1910. Hubble also became a member of the
Kappa Sigma Fraternity and in 1948 was named Kappa Sigma "Man of the Year". He spent the next three years as one of Oxford's first
Rhodes Scholars, where he originally studied
jurisprudence, before switching his major to Spanish and receiving the
MA degree, after which he returned to the
United States. Some of his British mannerisms and dress stayed with him all his life, occasionally irritating his American colleagues.
Returning to the United States he worked as a
high school teacher and a
basketball coach at
New Albany High School in
New Albany, Indiana (near
Louisville), and was a member of the Kentucky
bar, although he reportedly never actually practiced law in
Kentucky. He served in
World War I and quickly advanced to the rank of
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 at the
Aberdeen Proving Ground during
World War II. For his work there he received the
Legion of Merit. Shortly before his death, Palomar's 200-inch
Hale Telescope was completed; Hubble was the first to use it. Hubble continued his researches at the Mount Wilson and Palomar Observatories, where he remained active until his death.
Hubble died of a
cerebral thrombosis on
September 28,
1953, in
San Marino, California. No funeral was held and his wife, Grace, didn't reveal what happened to his body .
Discoveries
The universe goes beyond the Milky Way galaxy
Hubble's arrival at Mount Wilson in 1919 coincided roughly with the completion of the 100-inch
Hooker Telescope, then the world's largest telescope. At that time, the prevailing view of the cosmos was that the universe consists entirely of the Milky Way galaxy. Using the Hooker Telescope, Hubble identified
Cepheid variables (a kind of
star; see also
standard candle) in several objects, including the
Andromeda Galaxy, which at that time were known as "
nebulae" and had been assumed to lie within the Milky Way. Hubble was first to suggest that these nebulae were in fact galaxies, and that our own galaxy was only one of many. This idea was opposed by the astronomy establishment at the time, particularly by the Harvard-based
Harlow Shapley. Yet Hubble's observations in 1922–1923 conclusively proved that nebulae were much more distant than previously thought and were hence galaxies themselves, rather than constituents of the
Milky Way. Announced on
January 1,
1925, this discovery fundamentally changed the view of the universe.
Hubble also devised the most commonly used
system for classifying galaxies, grouping them according to their appearance in
photographic images. He arranged the different groups of galaxies in what became known as the
Hubble sequence.
Redshift increases with distance
Hubble was generally incorrectly credited with discovering the
redshift of galaxies. These measurements and their significance were understood before 1918 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. 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
equations of general relativity for a
homogeneous, isotropic expanding space. Although concepts underlying an
expanding universe were well understood earlier, this statement by Hubble and Humason led 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 was the first observational support for the
Big Bang theory which had been proposed by
Alexander Friedmann in 1922. The observed velocities of distant galaxies, taken together with the
cosmological principle appeared to show that the Universe was expanding in a manner consistent with the
Friedmann-Lemaître model of
general relativity. In 1931 Hubble wrote a letter to the Dutch cosmologist
Willem De Sitter expressing his opinion on the theoretical interpretation of the redshift-distance relation:
» "... we use the term 'apparent velocities' in order to emphasize the empirical feature of the correlation. The interpretation, we feel, should be left to you and the very few others who are competent to discuss the matter with authority."
Today, the 'apparent velocities' in question are considered to be artifacts of a
coordinate transformation that occurs in an
expanding space. Light traveling through stretching space will experience a Hubble-type redshift, a mechanism different from the
Doppler effect.
In the 1930s Hubble was involved in determining the distribution of galaxies and
spatial curvature. These data seemed to indicate that the universe was
flat and homogeneous, but there was a deviation from flatness at large redshifts. According to
Allan Sandage,
» "Hubble believed that his count data gave a more reasonable result concerning spatial curvature if the redshift correction was made assuming no recession. To the very end of his writings he maintained this position, favouring (or at the very least keeping open) the model where no true expansion exists, and therefore that the redshift "represents a hitherto unrecognized principle of nature."
There were methodological problems with Hubble's survey technique that showed a deviation from flatness at large redshifts. In particular the technique didn't account for changes in luminosity of galaxies due to
galaxy evolution.
Earlier, in 1917,
Albert Einstein had found that his newly developed theory of general 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 [his] life".
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.
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 unsuccessful in Hubble's life time, but shortly after his death the Nobel Prize Committee decided that astronomical work would be eligible for the physics prize.
Honors
Awards
Further Information
Get more info on 'Edwin Hubble'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://edwin_hubble.totallyexplained.com">Edwin Hubble Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
