September 19, 2002
- Special
Report: Penn research brings knowledge to the world
A look into the growth and workings of Penn's half-billion-dollar research enterprise. - How Penn's research enterprise works and grows
- Penn brings the fruits of research to market
- How Penn became a giant in advancing knowledge
- Desert's past discovered
- Research gets its own Web site
- Penn calls up Marine as EVP
- Celebration of 150 years at SEAS
- A simple test offers hope
- School named for great alum
- One of a cast of hundreds
- Event Listings
- Editor's Pick: A night in Cuba—dine, dance and groove
- Conference Call
- People's Choice: Where do you park?
RESEARCH
Penn calls up Marine as EVP
BY STEVE BRADT
Photo by Candace diCarlo |
Of all the fundamental measures of our universe, temperature is the newcomer, identified as such by theoretical physicist Gino Segrè in a new book that makes temperature the theme of a journey through science, history and culture, revealing the surprisingly deep ways in which heat and cold have shaped humans and their world.
“A Matter of Degrees: What Temperature Reveals About the Past and Future of Our Species, Planet, and Universe” (Viking), Segrè’s first book, moves from the blazing hearts of faraway stars to physicists’ drive toward absolute zero, from global warming to heat-sensitive proteins in the human body.
First measured in the 17th century, millennia after time and distance were first quantified, temperature is, in Segrè’s view, an appropriate yardstick for measuring the progress of humanity.
“If I were to employ temperature as my record for a narrative of civilization,” Segrè wrote, “I would cite the ever-hotter fires humans made as they moved … from the Stone Age’s first fires to charcoal and then to the bellows that produced bronze and iron. Going further, I would reach the steam engine, the 19th century’s great Bessemer furnaces that made steel, and finally the Nuclear Age. …For the past 200 years, I could use as a marker the ever-lower temperatures achieved in laboratories as, one by one, all known species of gas were liquefied. As the millennium came to an end, the low-temperature scale reached billionths of a degree above absolute zero.”
Ever wonder what’s so special about 98.6 degrees Fahrenheit, or why we consider room temperature to be around 70 degrees? Segrè explained that people feel most comfortable in settings some 20 to 30 degrees below body temperature because that differential produces a comfortable rate of heat loss. Perhaps it is not a coincidence that humans emerged 2 million years ago in parts of Africa where median temperatures are in the low 70s.
In another passage linking temperature to human evolution, Segrè marveled at how scattered radioactivity in the Earth’s crust has essentially given rise to humans: He wrote: “The radioactive alpha particle decay of a few kinds of nuclei heats the Earth’s crust, which convectively creates fire just below the surface. Forced up through the ocean bottom in hydrothermal vents, this activity somehow sustains life that evolves to create creatures that think about radioactivity.”
Far beyond the confines of humanity, Segrè describes the history of our universe in terms of its evolution from the 100-billion-degree Big Bang to the average of a few degrees above absolute zero found across today’s cold, sparse universe. Along the way, the warm interstellar dust near our newborn sun condensed into moderately sized planets, while much lower temperatures further afield froze the primordial soup into giants like Saturn and Jupiter.
Segrè, a Penn professor since 1967, described physics as his “family business.” Nephew of particle physicist and Nobel laureate Emilio Segrè, he is also the brother, son-in-law, uncle and cousin of physicists.
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