The Expanding Universe: Edwin P. Hubble and the Mount Wilson Observatory, 1919-1929

by Paul R. Spitzzeri

From the thrilling climb up from the San Gabriel Valley to Mount Lowe in yesterday’s post, we reach for the stars and beyond today with highlighted artifacts from the Homestead’s collection relating to the Mount Wilson Observatory and ground (sky?) breaking work conducted there by Edwin P. Hubble from 1920 onward.

These include a quartet of photographs showing the exteriors and interiors of observatory structures, including a 150-foot tall tower and the large domed observatory building where some of the most important work ever conducted in the discipline of cosmology have taken place—including the work of Hubble and others.

Hubble Andromeda Times_Mar_14__1925_
Los Angeles Times, 14 March 1925.

A recent interest in the subject has led to the reading of a number of books over the last several years on cosmology, the current one being Before the Big Bang by Brian Clegg, of which about a third remains to be read.  It was intriguing to read Clegg’s analysis of Hubble’s work at Mount Wilson with respect to the Milky Way not being the whole of the universe and his discovery that the universe was rapidly expanding rather than fixed.

Clegg pointed out in his fascinating book exploring theories of what there was before the Big Bang that astronomist George Ellery Hale was funded by the Carnegie Institution (established by U.S. Steel mogul Andrew Carnegie) to establish an observatory in southern California.  The weather here being far superior to that of such places as the Yerkes Observatory in Wisconsin, northwest of Chicago, Hale chose Mt. Wilson over Mt. Palomar near San Diego because of accessibility.

19117 RPPC Mt Wilson Observatory and Telescope Tower 2016.134.1.34
This first of four images here from the Homestead’s collection shows the Mount Wilson Lodge with a 150-foot tall observatory tower to the right.

Hale brought the Yerkes facility’s 60-inch telescope west to Mt. Wilson, dubbed a solar observatory because of the emphasis of study of the sun, when the observatory opened in 1904, but added a 100-inch one, the largest in the world for over three decades, in 1917.  Two years later, the use of “solar” was dropped from the name of the observatory and, in 1923, Hale stepped down as director and was replaced by Walter S. Adams.

As for Hubble, who was born in Missouri in 1889, he was pushed to study a more practical subject at the University of Chicago, so he earned a law degree.  He managed, though, to take a plethora of astronomy courses as well as to become a Rhodes Scholar at Oxford (where he dressed and talked like a native Brit, affectations he maintained the rest of his life.)

Hubble New Universes Times_Feb_19__1926_
Times, 19 February 1926.

After completing his studies, Hubble had to attend to return home to deal with the financial situation left after his father’s death.  After that, he went to work for the University of Chicago’s Yerkes Observatory and then moved west to take a position, a century ago this year, at Mt. Wilson.  Clegg wrote:

The life of the astronomers based at Mount Wilson in the 1920s was a strange one.  Not only was the site isolated, high up a narrow tracks littered with hairpin bends, but working there involved a rigorous schedule where nights on the telescope were interlaced with days interpreting the photographic plates used to record images of the stars.  In the basic accommodation up on the mountaintop that the called the Monastery, there were only limited comforts, and the observatories had to be kept at freezing night-time temperatures to avoid distortion from the haze any heating would cause.  Hubble took to striding about the place in his army greatcoat, cementing his eccentric image.

Considered strange or not, the astronomer made his name in fall 1923 when he found that a star called a Cepheid variable was situated 900,000 light years from earth, which was way past the limits of our Milky Way, thought to have been the whole of the universe.  In succeeding years, his observations revealed that our Milky Way galaxy was just one of a huge number in a gigantic and maybe infinite universe.

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Another photo showing the 150-foot tall tower.

It is hard to overstate Hubble’s achievement, given that the Milky Way is some 100,000 light years across, but he’d found nebulae that were more than ten times further out and even these were ones that were visible.  It was likely there were more beyond the observations he and his colleagues were making, but Hubble waited until he found a second Cepheid variable to confirm his findings.

Meanwhile, Willem de Sitter, an astronomer in the Netherlands, posited an idea that the universe was not finite, but was expanding.  Russian physicist Aleksandr Friedmann utilized Albert Einstein’s general relativity theory to demonstrate that space was either expanding or contracting.

Hubble studies stars Times_Jan_31__1927_
Times, 31 January 1927.

Georges Lamaitre, an unusual combination of a physicist and Catholic priest, developed a theory of the expansion of space through corroboration with cosmic rays which, as Clegg notes, “are showers of high-energy particles that spatter the solar system from out in the depths of the universe”.  For the French scientist, the Big Bang sent energy and particles of matter in all directions, some of which formed into stars and planets through gravitational attraction.  But, ones with more energy would continue to move throughout space and be seen in cosmic rays.

In another recent book I read, Quantum by Manjit Kumar, the famed Solvay conference of 1927, which featured half of the 29 attendees as Nobel Prize winners, was marked by Einstein’s conflict with Danish physicist Niels Bohr on the newly-minted quantum theory, dealing with matter and forces beyond observance.  At the meeting, however, Einstein also expressed his opposition to the concept of an expanding universe, hoping to demonstrate its fixed size through a unified field theory that he worked on, unsuccessfully, until his death over a quarter century later.

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The large ground-level domed observatory buildings (note the five persons standing next to it for scale) and the tower behind the trees at the right.

Yet, what Hubble found in continuing his work at Mt. Wilson was that the further away a galaxy was from our own Milky Way, the faster it was moving from us.  What was believed to be a fixed universe was one that was growing at enormous speed.  As Clegg noted, “the technology that made this observation possible relied on colors and was first used to discover with remarkable accuracy just what elements were present in stars.”  From there, the expansion of the universe was explainable.

What Hubble determined is that “we can look at the light from a star or galaxy and see how much of it has been shifted” as it moved.  Clegg continued, “From this, it is not difficult to work out how fast the distant body is moving with respect to us.”  American Vesto Slipher, in the 1910s, measured “red shifts” in some nebulae and “blue shifts” in others and suggested that these were moving at staggering speed through our galaxy, though they were outside of it in the larger universe that Hubble later revealed.

What's New in Science Times_Nov_10__1929_
Times, 10 November 1929.  Here, Milton Humason, Hubble’s assistant, gets some media attention.

Working with assistant Milton Humason, whose modesty coupled with Hubble’s media savvy meant that the later became famous and the former obscure, Hubble revealed in 1929 that, as expressed by Clegg, “not only were most of the other galaxies moving away from ours, the farther away they were, the faster they receded.”  Moreover, if you doubled the distance, you also doubled the rate and this became known as Hubble’s Law.

Notably, the difference in red and blue shifts, meant that, for those galaxies heading towards our Milky Way, they were, as Slipher hypothesized, “blue shifted.”  These were the ones closest to our own, were less affected by universal expansion, and affected by gravitational forces.  As Clegg noted, however,

Hubble was happy to have established the relationship in speed between galaxies, but was not prepared to follow this through and suggest that this meant everything had started in a Big Bang.

However, if Hubble’s view of the universe as we see it now was accurate, it was only reasonable to suggest that the cosmos started from a single location in time and space, a moment of universal creation, the Big Bang.

He continued by noting that, while we could trace the trail of galaxy formation became to “a single location for the beginning of everything,” it was also clear that “because the whole of space has expanded out from that point . . . what is now all of space corresponds to the point where the Big Bang happened.  It has just stretched out in all directions like three-dimensional taffy.”

1018080RPPC Mt Wilson Observatory Telescope 2015.265.1.1
A great photo of the massive 100-inch telescope, installed in 1917 and which was the largest in the world for decades.

It is stunning to think that these astounding revelations of the much-larger universe and its blistering speed of expansion were made in the 1920s right here in greater Los Angeles at the Mt. Wilson Observatory.  From Hubble’s staggering discoveries, cosmology has continued, with no small amount of controversy, to seek more understanding of our universe (or, perhaps, multiverses!), its origins, its possible futures and other components that reflect the ceaseless search for how life began.

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