Origins Hubble a view to the edge of space  
people ideas tools place

Who was Hubble?



Edwin Hubble: The Great Synthesizer
Revealing the breadth and birth of the universe

by Liza Gross

Edwin Hubble, visionary astronomer and founder of modern cosmology, was a man of surprising talents. He may be the only intellectual giant in history to have had a shot at both the Nobel prize and the heavyweight boxing title of the world.

Hubble was born in Marshfield, Missouri, in 1889, and moved with his family to Chicago nine years later. He earned a degree in mathematics and astronomy at the University of Chicago in 1910, as well as a reputation as a gifted boxer. While at Chicago, promoters courted him as the next "great white hope"--their pick to dethrone controversial African-American heavyweight champ Jack Johnson. Instead, Hubble accepted a Rhodes scholarship to Oxford, earned a degree in law, and ultimately turned to astronomy, a field he described as "a calling."

When Hubble began working in astronomy in 1919, scientists were still debating whether the Milky Way--earth's galactic home--constituted the entire universe, or whether ours was just one of many galaxies inhabiting a far larger space. But they couldn't resolve the issue without better telescopes. Hubble was lucky enough to start his career at California's Mount Wilson Observatory, where the largest and most technologically advanced telescope in the world had just been built.

From his mountain perch high above Los Angeles, Hubble set his sights on fuzzy clouds of cosmic light called nebulas--and hit the jackpot. Within one of those clouds, known as the Andromeda nebula, he detected cepheids (pronounced CEE-feeds)--"variable stars" that regularly change in luminosity.

Thanks to the pioneering work of Henrietta Leavitt, who had developed a technique using variable stars as a measure of distance, Hubble determined that his cepheids were much too far away to be part of our own galaxy. He realized, in fact, that the Andromeda nebula itself wasn't a nebula at all, but a galaxy made up of billions of stars, just like our own. His discovery proved that our Milky Way is just one of many galaxies, settling the controversy once and for all, and forever changing the way we view our place in the universe.

Edwin Hubble
Edwin Hubble at work.

But Hubble's shining moment was yet to come. The history of scientific discovery is a history of the unexpected, and what Hubble would soon reveal was no exception.

By the early 1900s, astronomy had taken some giant leaps forward. Scientists could not only determine how far away a galaxy was (using cepheids), but they had also figured out a way to use the light from a galaxy to determine how fast it was moving.

From our point of view, the spectra of light emitted by celestial bodies shifts depending upon whether they're moving toward or away from earth. Galaxies moving toward earth shift toward the blue end of the spectrum; those moving away shift toward the red. By plotting the distance of eighteen galaxies against their red shifts , Hubble discovered a direct relationship: Galaxies were moving away from earth at a rate proportional to their distance from us.

Hubble's discovery was not just unexpected, but monumental. No one had thought to compare these data points before. Using the ratios he observed, Hubble determined that the farther the galaxy, the greater the red shift. In other words, the greater the distance between a galaxy and the earth, the faster that galaxy was moving away from us. (And the greater the distance between galaxies, the faster they were moving away from each other.) This phenomenon, known today as Hubble's law , meant that the universe was expanding.

From this realization, Hubble went one step further. If galaxies that were twice as far away were moving away from each other at twice the speed, he reasoned, they must have begun their cosmic expansion from the same space at the same time. Using his distance/speed ratio, Hubble fixed that time at about two billion years ago. He was off by some ten to thirteen billion years by today's estimates, but he laid the foundation for the Big Bang theory , providing evidence that the universe exploded into existence with a furious burst of energy, and has been expanding ever since. It was a shattering blow to the centuries-old notion of a static universe.

Near the end of Hubble's career, around 1948, a BBC reporter asked him what he hoped to find with the immense telescope he'd helped develop for Mount Palomar in Southern California. "We hope to find something we hadn't expected," Hubble replied.

While Hubble never did win the Nobel Prize (there was no category for astronomy at the time), his legacy reaches far beyond such temporal tokens of recognition. Stephen Hawking, noted cosmologist and author of A Brief History of Time, has hailed Hubble's expanding-universe discovery as "one of the great intellectual revolutions in the twentieth century."

Today, it's only fitting that our most finely tuned eye on the universe--the Hubble telescope--bears the name of the man who pushed the limits of our understanding of the nature and structure of space. It's surely just a matter of time before Hubble takes his rightful place among the astronomical heavyweights. Like Copernicus and Galileo, Hubble was light-years ahead of his time, forever changing our view of the heavens--and ourselves.




© Exploratorium