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17 April 2014 12:48 pm ,
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Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Microwave Ripples Reveal a Flat Universe
18 December 1998 7:00 pm
PARIS--Astrophysicists may have the best indication yet that the cosmos contains the full complement of matter and energy. Observations of the big bang's faint afterglow, made by two microwave telescopes at the South Pole and announced here today at a conference called--despite the location--the 19th Texas Symposium on Relativistic Astrophysics and Cosmology, should reassure theorists that their favorite theory of how the big bang got started, called inflation, could be correct.
The ripples in the cosmic background radiation (CMB) record slight irregularities in the distribution of the early universe's matter. The apparent size of these waves reflects the geometry of the universe: If the ripples are most common at a size of about 1 degree on the sky, the universe is "flat," which means that if made only of matter, it should eventually stop expanding. But if the universe's empty space is stocked with a hypothetical type of energy (called the cosmological constant), expansion could even be speeding up--just as recent measurements of distant exploding stars suggest. Shape is crucial to astronomers, because a flat universe is a key prediction of the simplest version of the inflation theory.
Tentative hints of a flat universe had come from measurements taken by balloons launched near Saskatoon, Canada, and from the Cambridge Anisotropy Telescope in the United Kingdom. Now more details have come from South Pole experiments, called Python and Viper, which take advantage of the thin, dry air at the South Pole for a clear view of the CMB. Their findings, presented in talks this afternoon, reveal a peak in ripples of the telltale 1-degree scale. "It's a very nice observation," says Neta Bahcall of Princeton University. "It's very suggestive."