Paula Cleggett-Haleim
Headquarters, Washington, D.C.                                                
January 7, 1993
(Phone:  202/358-0883)                                                           
10:30 A.M. EST

Randee Exler
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  301/286-7277)


RELEASE:  93-5

BIG BANG THEORY PASSES TOUGHEST TEST 


   The Big Bang Theory passed its toughest test yet with the 
latest results reported from NASA's Cosmic Background Explorer 
(COBE) team at the American Astronomical Society meeting in 
Phoenix, Ariz., today.

   Precise measurements made by COBE's FIRAS of the afterglow 
from the Big Bang -- the primeval explosion that began the 
universe approximately 15 billion years ago -- show that 99.97 
percent of the early radiant energy of the universe was released 
within the first year after the Big Bang itself.

   "Radiant energy" is energy emitted in any form of light, from 
x-rays and gamma rays to visible and infrared light or even radio 
waves.  Cobe's Far Infrared Absolute Spectrophotometer (FIRAS) 
was designed to receive the microwave and infrared energy from 
the Big Bang.

   "The Big Bang theory comes out a winner," said COBE Project 
Scientist and FIRAS Principal Investigator Dr. John C. Mather of 
NASA's Goddard Space Flight Center, Greenbelt, Md.  "This is the 
ultimate in tracing one's cosmic roots," Mather said.

   All theories that attempt to explain the origin of large scale 
structure seen in the universe today now must conform to the 
constraints imposed by these latest measurements.

   This includes theories that postulate large amounts of energy 
released by such things as black holes, exploding supermassive 
stars or the decay of unstable elementary particles.  In other 
words, there were not a lot of "little bangs," as suggested by 
some theories.
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   The Big Bang Theory predicts that the spectrum of relic 
radiation should be that of a perfect "black body" unless there 
were major energy releases more than a year after the explosion.  
(A black body is a hypothetical cosmic body that absorbs all 
radiation falling on it, but reflects none what-so-ever.  A black 
body emits at the same temperature at every wavelength.)  These 
latest FIRAS results reveal that later energy releases did not 
occur.

   The COBE scientists now can say that the temperature of the 
afterglow radiation is 2.726 degrees above absolute zero (273 
degrees below zero on the Celsius scale) with an uncertainty of 
only 0.01 degrees.

   Today's announcement is the result of analyzing data from the 
FIRAS during its 10 months of observations.  Hundreds of millions 
of measurements were combined to obtain these unprecedentedly 
precise results.

   "Making certain that all of the measurements were combined 
correctly required exquisitely careful work and lengthy analysis 
by a large team of COBE scientists," Mather reported.

   "We are seeing the cold glow still remaining from the 
initially very hot Big Bang.  These results now limit the size of 
any 'after shocks' following the Big Bang.  The closer we examine 
the Big Bang the simpler the picture gets," said Mather.

   "It took us 18 years of careful effort to reach this point, 
but now we can say that the Big Bang Theory has been tested 
against observations to a fine degree of precision," explained 
Mather.

   "Experimental evidence of the Big Bang was first found by 
Edwin Hubble in the 1920's.  He found that distant galaxies in 
ever direction are going away from us with speeds proportional to 
their distance.  Therefore, gallaxies that are farther away are 
going faster.  This is exactly the pattern that would occur if 
the entire universe originated in a single explosion, now called 
the Big Bang.

   Papers on these results and their implications soon will be 
submitted to the Astrophysical Journal for publication.

   COBE, launched Nov. 18, 1989, is managed by NASA's Goddard 
Space Flight Center, for NASA's Office of Space Science and 
Applications, Astrophysics Division, Washington, D.C. 

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