The Big Bang Theory and Its Proofs; #2 Cosmic Background Radiation

   

<Picture 1, The Big Bang Theory(sitcom)>

 

   In the last post, we discussed about The Doppler Effect as a proof of the big bang theory. We could figure out why is the red shift in astronomical observations the proof of the expansion. But the red shift in the Doppler effect is not the only one as a proof of the expansion. Today, We're gonna talk about the cosmic background radiation as an another proof.

 

 

1. To Find a Homogeneity

  

 

<Picture 2, The Horn Antenna on which Penzias and Wilson discovered the CMB>

   The Cosmic Background Radiation was first predicted in 1948 by Ralph Alpher, and Robert Herman. They said that if there was a big bang, the expansion of the universe would have stretched and cooled the high-energy radiation of the universe down to a temperature of about 5 K. Their estimate was not exact, but their idea was great.
 

   The Cosmic Background Radiation is an electromagnetic radiation from the universe. If it were from our galaxy, we could easily figure out its direction with the difference of powers. But if it came from every directions with the same power, then the radiation would not be from our galaxy. It might be extremely far away from our galaxy so that we can't distinguish the slight difference of the powers. 
 

  In 1964, Arno Penzias and Robert Wilson made a first measurement showing the presence of the microwave background. It strongly supported the big bang theory with explaining the homogeneity and black body radiation. It was the tipping point for the big bang theory to defeat the steady state theory.

 

2. To Find a Inhomogeneity

  

 

 
 

   However, the game was not over. The supporters for big bang thought that early universe is homogeneous but not perfectly homogeneous. because if it were perfectly homogeneous, then there are no density or gravity differences between space. In addition, if there were no density differences, then there are no stars and galaxies now. So, they had to find the inhomogeneity of radiation with more precise instruments to support the big bang theory.

 

 

<Picture 3, The picture of COBE>

 

   For the detail investigation, NASA sent a satellite COBE(Cosmic Background Explorer) to explore the cosmic background radiation. COBE constantly accumulated the measurement and concluded that the temperature of the universe is 2.278±0.002K which is same as the blackbody curve. It confirmed that the radiation is a proof of the expansion and the team received Nobel Prize in physics for 2006 for this discovery.

   

<Picture 4, CMB Spectrum from COBE>

  3. The Biggest Map in the World

 

 

 

 

<Picture 5, CMB Map from COBE WMAP>

 

   Currently many astrophysicists are trying to figure out the Dark Matter and the Dark Energy. The map of the COBE is a treasure to them. However there are so many things undiscovered in the universe. With the efforts to figure out the beginning of the universe, we could step forward to the face of the universe.

 

   In the next post, I'm gonna talk about the Special Relative Theory and Twin Paradox. Thank you for reading it.

 

Bibiology

 

Sagan, C. E., 1980, Cosmos(1st ed.), New York: Random House.

Gamow, G. 1948, "The evolution of the universe", Nature 162.

Robert Wilson, 1978, The Cosmic Microwave Background Radiation.

Peebles, P. J. E., 1991, "The case for the relativistic hot big bang cosmology", Nature 352.

Smooth, G. F., 1992, "Structure in the COBE differential microwave radiometer first-year maps", Astrophysical Journal Letters 396.

Bennett, C. L., 1996, "Four-Year COBE DMR Cosmic Microwave Background Observations: Maps and Basic Results", Astrophysical Journal Letters 464.

http://navercast.naver.com/contents.nhn?rid=20&contents_id=2217

 

2016.04.06. Han Kwang Hee