Edwin Hubble

When taking account of the greatest scientists of history, names like Newton and Einstein come quickly to mind. But, it was the astronomer Edwin Hubble who dared to believe that our universe could extend beyond the confines of our Milky Way Galaxy -- and had the genius to prove it.

Quick Facts

Born:
November 29, 1889 in Marshfield Missouri
Died:
September 28, 1953 in San Marino, California
Education:

• BS in mathematics, astronomy and Philosophy at University of Chicago (1910)
• MS in Spanish, Oxford University (1913)
• PhD in astronomy, University of Chicago (1917)

Accomplishments:

• Determined that the universe extends beyond the Milky Way Galaxy, and that other galaxies exist.
• Showed that galaxies are receding from us at velocities proportional to their distance away from us.

His Early Life and Education

Edwin Hubble was born November 29, 1889, in the small town of Marshfield Missouri. He moved with his family to Chicago when he was 9 years old, and remained there to attend the University of Chicago, where he received a bachelor’s degree in mathematics, astronomy and philosophy.

He then left for Oxford University on a Rhodes Scholarship, which he received for his academic excellence as well as his athletic aptitude. But because of the dying wishes of his father, he put his career in the sciences on hold, and instead studied law, literature and Spanish.

Upon completion of his studies, Hubble returned to America in 1913 and spent the next year teaching high school Spanish, physics and mathematics at New Albany High School in New Albany, Indiana. But he could no longer deny his calling to the sciences, and enrolled as a graduate student at the Yerkes Observatory in Wisconsin.

Eventually, his work led him back to the University of Chicago, where he received his PhD in 1917. His thesis, titled Photographic Investigations of Faint Nebulae, laid the foundation for the work that changed the face of astronomy.

Immediately upon completing his graduate studies, Hubble was offered a position at the Yerkes Observatory, but instead chose to enlist in the army to serve his country in World War I. He quickly rose to the rank of Major, and was injured in combat before being discharged in 1919. Hubble then arrived at the Mount Wilson Observatory, still in uniform, where he had access to both the 60-inch and, newly completed, 100-inch Hooker reflectors. Hubble effectively spent the remainder of his career here, passing away shortly after the completion of the 200-inch Hale telescope which he helped design.

 Measuring the Size of the Universe

In the early 1920s the commonly held wisdom was that the fuzzy spiral objects in the sky were simply another classification of nebulae. Nebulae were popular objects of observation, and a lot of effort was spent trying to explain how this spiral variety would form. The idea that these spiral nebulae could actually be whole other galaxies was not even a consideration. At the time it was thought that the entire universe was encapsulated by the Milky Way Galaxy -- the extent of which had been precisely measured by Hubble’s rival, Harlow Shapley.

Using the 100-inch Hooker reflector, then the most powerful telescope in the world, Hubble was able to take extremely detailed measurements of several spiral nebulae. In these measurements he identified several cepheid variables -- a type of variable star whose distance from the observer can be precisely determined by measuring its luminosity and period of variability -- inside the nebulae. Based on these measurements, he concluded that the nebulae could not lie within the Milky Way.

Hubble’s findings met great resistance in the scientific community, including Harlow Shapley initially. Ironically, Hubble’s methodology was the same used by Shapley to determine the size of the Milky Way. So, it was primarily the magnitude of the paradigm shifting result that caused scientists to take pause. Eventually, the undeniable integrity of Hubble’s work won the day.

 The Redshift Problem

While Hubble’s discovery of the extent of the universe undoubtedly made his career, he quickly moved onto a new problem. The redshift problem had plagued astronomers for years. Namely, spectroscopic measurements of spiral nebulae (Hubble continued to use the term nebulae instead of calling them galaxies), showed that their light was shifted toward the red end of the spectrum.

The conclusion reached was that the galaxies must be receding from us at high velocity, a phenomenon known as doppler shifting. Using this information, Hubble, and his colleague Milton Humason, found a relation now known as Hubble’s law. This law relates the distance of a galaxy from the Milky Way to the velocity with which it recedes from us. Simply, the further away a galaxy is from us, the more quickly it is moving away.

The Nobel Prize

Edwin Hubble was never considered for the Nobel Prize, but it was not due to a lack of scientific achievement. At the time, astronomy was not recognized as a physics discipline, therefore astronomers could not be considered.

Hubble advocated for this change, and at one point even hired a publicity agent to lobby on his behalf. In 1953, the year Hubble died, astronomy was formally declared a branch of physics, and therefore paved the way for astronomers to be considered for the prize. Had he not died, it was widely felt that Hubble would have been named that year’s recipient (the Nobel Prize is not awarded posthumously).

Hubble Space Telescope

Hubble’s legacy lives on though, as his name adorns the Hubble Space Telescope (HST), which has spent more than a decade beaming back spectacular images from the deepest regions of the universe.

References

Michael D. Lemonick, Edwin Hubble, Time Magazine (March 1999).
Allan Sandage, Edwin Hubble 1889 - 1953, The Journal of the Royal Astronomical Society of Canada, Vol. 83, No. 6 (December 1989).