An Academic Lecture is Also a Homecoming for Stephon Alexander
During the coldest days of December, Associate Professor of Physics Stephon Alexander '93 got a warm welcome from his home country of Trinidad when he traveled to the Caribbean island to give a presentation at the International School for Young Astronomers (ISYA).
The ISYA has been educating young scientists for more than 30 years, but this was the first time the school's sessions were held in Trinidad, according to Alexander.“It was a good platform to promote astronomy and cosmology in [the area] and show the government that it is a worthy cause,” he says.
Alexander delivered his“Lectures on Relativistic Cosmological Structure Formation” in two parts. The first was a technical talk geared towards ISYA undergraduates and graduate students representing 17 countries, and addressed the question of how the structures seen in the night sky (galaxies, stars and dark matter) formed from the universe's expansion dating back to the Big Bang.“The analogy I stressed was to think of the universe like a giant ocean of radiation and invisible matter,” says Alexander.“Ripples of this matter and radiation formed in the early universe and is predicted from Einstein's theory of general relativity.” Alexander showed students a physical picture of the early universe's process of structure formation, and explained how Einstein's theory described the growth of those ripples into the structures that are visible today.
The second part of Alexander's lecture focused on radiation found in the Cosmic Microwave Background, a fossil picture of the universe as it appeared roughly 14 billion years ago. Alexander, who is also a saxophonist, discussed how the patterns in this cosmological data can be analyzed in terms of acoustic and sound phenomena.
“It is these ripples in the primordial universe that grew into the planets, stars and galaxies in the cosmos,” he says.“However, in the early stages of the universe these ripples look and sound like resonant patterns of a â€˜universal' instrument.” Alexander revealed that the resonance of these first structures vibrated as an A note, which corresponded to the expansion rate of the universe. With saxophone in hand, he then gave a musical demonstration of his talk, playing the notes of the cosmological data and doing an improvisation based on the scales.
Alexander, who was also interviewed by the country's national television and radio journalists, was especially moved to meet with Trinidad's aspiring young physics and astronomers, who he treated to dinner one night.“They were loaded with questions, ranging from math to theology,” he says.“I was very impressed with their intellectual depth.”
In addition to the ISYA students, Alexander's lectures were attended by local musicians, including steel-pan players (â€œThey asked the best questions,” he reports) and, to his delight, members of his family who still live on the island.“I could tell that they were proud, and I was thinking, â€˜Oh, man, now they're going to finally see what I've been up to all these years.”