2006年VOA标准英语-Scientists Find Evidence Universe Inflated（在线收听）

By David McAlary
Washington
17 March 2006
 
Scientists report evidence that the universe was born in less than the blink of an eye, expanding instantly from sub-microscopic size to astronomical proportions. The conclusion comes from data gathered by a U.S. satellite that has been peering for clues to the origin of the cosmos in a faint glow of background radiation that is almost as old as the universe.

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Inflation means one thing to economists and another to cosmologists. When applied to the universe, it means the expansion from its tiny origins nearly 14 billion years ago.

Time line of the Universe   
  

Now, scientists have a better idea of how fast this happened, thanks to a U.S. satellite orbiting four times farther than the moon. It is called the Wilkinson Microwave Anisotropy Probe, or WMAP for short, launched in 2001.

The probe's chief investigator, astrophysicist Charles Bennett of The Johns Hopkins University in Baltimore, says the data reveal that the infant universe just popped out suddenly from almost nothing. It inflated from the size of a pea to a volume larger than all current observable space in less than one-trillionth of a second.

"It amazes me that we can say anything at all about what transpired in the first trillionth of a second, but we can," he said. "It appears that the universe had a growth spurt that would alarm any mom or dad."

This conclusion comes after three years of continuous observations of the oldest light in the universe. Bennett says it is the remnant afterglow of light that first appeared when the universe was just 300,000-years-old, a faint microscopic radiation that lingers at temperatures close to absolute zero, the temperature at which all atomic motion stops.

"WMAP measures the patterns of the light as a geologist might examine a fossil for clues of the past," he explained.

WMAP has produced a new, more detailed picture of the infant universe. Colors indicate "warmer" (red) and "cooler" (blue) spots   
  
The WMAP results give the most detailed picture yet of the minute brightness and temperature variations in this light, heat differences of less than one-millionth of a degree. Those variations, first measured in the 1990s by a previous U.S. satellite, are microwave fossils revealing the emerging structure of the infant universe.

The slightly warmer, brighter regions represent areas where matter began clumping together, eventually growing into galaxies, stars and planets. The cooler, darker areas were less dense, becoming the space between these structures.

It is in these patterns that the researchers discerned the details of the universe's beginning, aided by a new map of the polarization, or direction, of the faint microwave radiation.

The WMAP researchers say their findings, combined with other cosmology information, support established theories on the universe's expansion. These theories hold that at the outset, short-lived bursts of energy at the atomic level were converted during the rapid inflation into the fluctuations of matter WMAP has measured more precisely than ever.

"WMAP has subjected our basic cosmological model to its most rigorous test and passed with flying colors," said Princeton University team member David Spergel.

Content of the Universe
  
  
The new data also inform scientists that only four-percent of the universe is ordinary matter that we can see. Twenty-two percent is unidentified dark matter, and 74 percent is a mysterious dark energy. This is a force scientists believe counters the gravitational pull of matter and is causing another rapid expansion of the universe, although not nearly as forceful as the first one.

"The observations are spectacular and the conclusions are stunning," he said.

This is Columbia University cosmology theorist Peter Greene, who was not part of the WMAP research team.

"Our species is one that seeks its origin, and the deepest of all questions of origin is, how did the universe begin? WMAP has certainly not answered this question, but WMAP's data is taking us one giant step closer to the answer by giving us a precise quantitative look at what happened literally at time zero itself," he said.

The WMAP data are to be published in the Astrophysical Journal. The WMAP satellite will continue to refine its data on a mission expected to last until 2009.