Edwin Powell Hubble (1889-1953) was an astronomer whose observations have revolutionized astronomy. His studies of galaxies in the universe besides our own led him to conclude that our universe was expanding outwards. It must have come from a central point of origin, and that something must have caused that expansion to begin with, giving birth to the Big Bang Theory.
He studied at the University of Chicago and concentrated on mathematics, astronomy and philosophy. When he graduated, he went to England and studied law at Oxford. He became a lawyer and moved back to the U.S. to practice law. But his interests lay elsewhere, in astronomy.
He returned to the University of Chicago and received his PhD in astronomy with a dissertation titled “Photographic Investigations of Faint Nebulae.”
World War I
When the war broke out, he joined the US Army, reaching the rank of major. He stayed there until 1919.
The Mount Wilson Observatory
In 1919, with the Hooker telescope completed and ready for observations, Hubble arrived at Mount Wilson. At that time, it was the largest telescope. His first work went to identify Cepheid variables and spiral nebulae. By 1922-23, his observations showed that these nebulae were so far away that they could not be part of the Milky Way Galaxy. This was the first indication that there were other galaxies in the universe.
The Hubble Sequence
The Hubble sequence is classification scheme for galaxies invented by Edwin Hubble in 1926. This system groups galaxies by on their appearance. So, because the scheme looks like a tuning fork, it is often called the Hubble tuning-fork diagram.
There are three broad classes in the scheme. Elliptical galaxies have smooth, featureless light distributions, making them look like ellipses in photos. Spiral galaxies look like a flattened disk with spiral arms and a concentration of stars at the center. Lenticular galaxies also have a bright central concentration of stars, but no spiral arms.
The Expansion of the Universe and Einstein’s Biggest Blunder
By 1929, after investigating how the galaxies were forming, Hubble noticed there was a red shift in the galaxies. Red-shift and blue-shift show how an object is moving. If an object is moving toward the observer, the photon frequency shortens in the direction of blue, that means higher energy. But if the object is moving away from the observer, the photon frequency enlarges toward the red side of the electro-magnetic spectrum, that means lower energy.
With this evidence, Hubble announced the Universe was expanding because the galaxies were moving away from the Milky Way Galaxy. This was an astounding finding. Moreover, it would have been a second supporting piece of evidence supporting Einstein’s General Theory of Relativity. (The first supporting evidence involved Mercury’s rotation around the Sun.) But something happened.
When Einstein first put together his General Theory of Relativity, he came to the same conclusion that the Universe was expanding.
But Einstein could not believe his own conclusion. So he went back and made a modification to the theory, introducing the Cosmological Constant, which made the Universe a static model.
However, when Hubble gave proof of the expanding universe, Einstein realized that he had been right initially. He said that the cosmological constant was his “biggest blunder.”
After this, Hubble was recognized as the most important Astronomer on Earth. Even Einstein met with him in 1931.
The Big Bang
With the universe expanding, astronomers began to think about what was causing the expansion. Within a short time, it became evident that the Universe had to have a central point of origin. Scientists, like Georges Lematre, in 1927 proposed a theory called the Big Bang, which was a large explosion that pushed the Universe away from the central point. The galactic expansion proof made this theory more plausible.
Distribution of Galaxies and Spatial Curvature
Hubble’s other contributions involved investigating whether the universe was flat and the distribution of galaxies throughout the universe. Hubble concluded that the red-shift showed that the universe was flat. However, other scientists were skeptical about very large red-shift phenomenon because it did not account for the luminosity changes in galaxy evolution.
World War II
Edwin Hubble left Mount Wilson in 1942 to help fight the Nazis in World War II. Although he first wanted to join the armed forces as he had done during the First World War, but he soon realized he could accomplish more by offering his services as a scientist.
In 1946, he received the Medal of Merit for exceptional conduct in providing outstanding services to citizens.
In 1948, he received the Honorary Fellow of Queen’s College, Oxford, for his contributions to astronomy.
Then, Hubble resumed his work at Mount Wilson, where he convinced his employers of the need for an even greater telescope than the current 100-inch reflector model so they could further explore the universe outside our galaxy. Hubble’s contribution was in the design of the Hale Telescope, which was set up at the Mount Palomar Observatory.
He broke ground with the honor of being the first to use it. He also told the BBC “We hope to find something we hadn’t expected” in response to a question about what to expect from the telescope.
Although he did not win the Nobel Prize for Physics, his name was under consideration. He would have won the prize had he not died. (The prize cannot be given post-mortem.)
He died from a cerebral thrombosis Sept. 28, l953. For many, he is the father of observational cosmology and considered as a pioneer in the investigation of distant stars and galaxies. In addition, one of the most popular and important space telescopes was named after him, The Hubble Space Telescope.