Astronomy professor gazes 15 billion years into the past
Ever since she was a little girl, Sandra Faber has been pondering the heavens. She recalls spending many evenings lying on the grass, gazing skyward and meditating upon the origins of our cosmos. “I think most kids look up with wonder at the night sky,” she says. “It just struck a chord of awe in me.”
Faber has spent her entire adult life pursuing that sense of awe. Now, as professor and chair of astronomy and astrophysics at UC Santa Cruz, she is working at the cutting edge of her field to answer the questions starry-eyed youths have been asking for centuries, including one enigma that puzzles scientists to this day.
Faber is leading a group of more than 100 observers from all over the world in a study that will utilize the Hubble Space Telescope to collect light from the furthest reaches of our universe in an effort to shed light on the formation of some of the earliest known galaxies. In the process she will gain a better understanding of black holes, and determine, once and for all, whether dark energy—the theoretical force astrophysicists suspect is at the root of our universe’s perpetually accelerating rate of expansion—is science fact or science fiction.
The Hubble Multi-Cycle Treasury Program will capture images of 250,000 galaxies, with the help of two very powerful cameras. The first, known as the Advanced Camera For Surveys, was installed in 2002 and can capture visible light from as far back as 9 billion years. However, Faber is more excited for the observations she will be able to make with the newly installed, infrared-sensitive Wide Field Camera 3. Using the Wide Field camera’s infrared capabilities, Faber will be able to peer back in time and get a good look at galaxies that formed around 13 billion years ago, roughly 600,000 years after the Big Bang, when the universe was still very much in its infancy, and when the rules governing cosmic development were different than they are now.
“Telescopes are humanity’s time machines,” she says.
Faber is certain that observing these young galaxies will yield new clues to many unanswered astrophysical questions. For one, she hopes to answer whether galaxies form around existing black holes or if it is the galaxies themselves that produce the ultra-dense gravitational behemoths.
Yet, while learning about galaxy development and black holes is of great interest to Faber, she is most excited for what the project will reveal about what she calls, aside from quantum theory, “the most puzzling and interesting discovery of modern physics”—dark energy.
Astrophysicists know that the universe has been expanding since the Big Bang. What is puzzling about our universe’s expansion, however, is that it appears to be speeding up. “If gravity works the way that it should, we should see that expansion slowing down,” Faber says. “It’s totally counterintuitive.”
This program, according to Faber, “will determine unequivocally whether there is dark energy in the universe, and, therefore, whether what appears to be the greatest puzzle in modern physics is really a puzzle or not.”
The researchers will answer this riddle by looking carefully at a particular class of supernovae—known as Type Ia supernovae, which are produced by the extremely powerful explosion of white dwarf stars. These Type Ia supernovae are also called “standard candles,” because astronomers believe that all Type Ia supernovae burn at the same brightness. By comparing nearby, present-day standard candles with their 13 billion-year-old predecessors—born when the mysterious force, currently explained as dark energy, was not active in the universe—the team will be able to determine two things with certainty: one, whether all Type 1a supernovae are the same brightness; and two, whether dark energy really exists.
Whatever information is gained from the observation, the program will be a success, Faber says. “This study is going to put the capstone on two of the major missions of Hubble,” she explains. It will have charted, for the first time, the earliest stages of galaxy evolution, and it will have added to the growing cache of data for future generations of astronomers to study and synthesize.
The telescope will be brought out of orbit soon, and gathering as much information as possible now is crucial to humanity’s understanding of how the universe operates, and, in turn, how we came to exist on this planet.
“Our existence on this planet is not magical,” Faber says, adding that it came as the result of natural processes, which began with the Big Bang and continue to this day. For Faber, understanding those processes is crucial for the betterment and perpetuation of mankind. “I think that astronomical knowledge is the most important knowledge,” she says. “We have to keep telling this story.”