Lecture reveals Mysteries of the Dark Universe
Mellon Institute Auditorium filled up once again this year with people ranging from high school students to college professors in order to hear Edward W. “Rocky” Kolb speak at this year’s Buhl Lecture. The Buhl Lecture, presented this year on April 21, is held annually at Carnegie Mellon to enhance both a scientific and non-scientific audience’s knowledge of recent physics discoveries.
This was Kolb’s second appearance at the Buhl Lecture. He first gave the Buhl Lecture in 1997, before dark matter was discovered. He was invited back by popular demand and gave a speech called “Mysteries of the Dark Universe.”
In his lecture, he said, “As we began the 21st century, two cosmic mysteries came to existence: dark matter and dark energy.”
He explained that dark matter is whatever is holding the galaxy together and dark energy is the property of empty space that drives galaxies apart. He then talked about the big-bang theory, from which scientists base the beginning of the universe.
Kolb added humor to the lecture, stating that the big-bang theory is not only an outstanding theory, but it is also a very popular television show. He went on to say that although it was thought to be nothing more than a theory, CBS has just officially validated The Big Bang Theory.
As a cosmologist, Kolb asks a simple question: “What is the universe made of?” The answer, however, is surprisingly complicated. In his lecture, Kolb noted that 95 percent of the universe is missing. He explained that, of the universe as a whole, “all the elements except hydrogen and helium only make up 0.025 percent of total mass energy,” and jokingly said, “thus proving that chemistry is not important.”
He went on to give a background of the history of discoveries about the universe.
“Throughout history, every civilization has had cosmology play a role in society,” Kolb said. In the early Newtonian theory, scientists believed that space and time remained fixed. Newton’s theory was, however, proven to be incorrect when Einstein revolutionized cosmology by discovering that “space and time are relative and can be curved, warped, and bent.” Through Einstein’s modified theory of gravity, cosmology became a science.
Kolb explained that Einstein developed 10 equations for this theory with the “left side equal to curvature and expansion of space and the right side equal to matter and radiation distributed through space.” Kolb emphasized that gravity is related to geometry, and that this forms the basis of Einstein’s theories of cosmology.
However, Einstein thought that the universe was stabilized and stationary, so he generated the cosmological constant in his equations, which Kolb referred to as a “fudge constant,” because they were adjusted to fit this stationary universe.
Then along came Edward Hubble, who created the Hubble Space Telescope, which determined that space is actually expanding (contrary to what Einstein believed).
Kolb stated that with such an expanding universe, there has to be more matter holding the universe together than what people can see in stars, and he called it dark matter. Dark matter is difficult to describe because it is essentially nothing. However, Kolb explained, nothing can actually be described as several aspects. “Nothing” matters (it counts toward the expansion of space), “nothing” is something (you cannot remove everything from space because quantum uncertainty cannot be removed), and “nothing” changes (dark matter is changing).
Kolb said that “Every atom in the body made of hydrogen or helium is ultimately made from a star.” An interesting thing he mentioned in his lecture is that “as we look out in space, we’re looking back in time ... the farther out we look, the farther back in time we go, but there is a limit.”
Kolb concluded the lecture by saying, “The universe emerged from a state of high temperature and density 14 billion years ago, and is expanding and cooling, evolving and dynamic ... the universe evolved from a simple, formless fog.”
He wrapped up the lecture by quoting Einstein: “The most beautiful thing we can experience is the mysterious.”
David Stone, a junior physics major, was attending the Buhl Lecture for the third year. He said, “I like coming to these lectures because they sometimes present new findings. Although [Kolb] summarized the findings from the past 10 years, I felt like he made it very presentable to the general audience and was very enlightening.”
Kolb is currently the department chair and Arthur Holly Compton Distinguished Service Professor of Astronomy at the University of Chicago. He is also a member of the Enrico Fermi Institute and Kavli Institute of Cosmological Physics, also at the University of Chicago.