December 21, 2000

2 min read

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A Big Boost for the Big Bang

By Kate Wong

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According to standard Big Bang model, our Universe started out very small and very hot. The so-called cosmic microwave background radiation (CMBR) that permeates the local Universe, astronomers believe, is a remnant glow from that infernal time. In theory, the temperature of the CMBR should increase steadily as researchers look back to earlier times. But recent measurements of the CMBR have focused on the microwave radiation near the Earth. Now new research, described today in the journal Nature, reveals the CMBR in a distant cloud, allowing astronomers to take the temperature of the young Universe for the first time. Their results provide strong support to the Big Bang theory.

Raghunathan Srianand of the Inter University Centre for Astronomy and Astrophysics in Pune, India, and his colleagues studied light from a far off quasar that had been absorbed by molecules in a gas cloud when the Universe was just a fifth of its current age. Some of the cloud's carbon atoms, they found, are in "fine-structured states"-- that is, they are slightly more energetic than the lowest energy states of carbon. Explaining such states requires that the cloud be surrounded by a warmer radiation field--one corresponding to a temperature between 6 and 14 degrees above absolute zero, as compared with the CMBR's present temperature of about 2.7 degrees. This, it turns out, accords well with theory's prediction of 9 degrees.

"The Big Bang theory has survived a crucial test," John Bahcall of the Institute for Advanced Study in Princeton, N.J., writes in a commentary accompanying the Nature report. "I am happy that the Big Bang theory passed this test, but it would have been more exciting if the theory had failed and we had to start looking for a new model of the evolution of the Universe.

Kate Wong is an award-winning science writer and senior editor for features at Scientific American, where she has focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for nearly 30 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home to the shores of Kenya’s Lake Turkana in search of the oldest stone tools in the world, as well as to Madagascar on an expedition to unearth ancient mammals and dinosaurs, the icy waters of Antarctica, where humpback whales feast on krill, and a “Big Day” race around the state of Connecticut to find as many bird species as possible in 24 hours. Wong is co-author, with Donald Johanson, of Lucy’s Legacy: The Quest for Human Origins. She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow her on Bluesky @katewong.bsky.social

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