The Cosmic Microwave Background
A Relic from the Origin of the Universe

The Cosmic Microwave Background, accidentally detected in 1964 by Arno Penzias and Robert Wilson, is widely believed to be the radiation remnant of the Big Bang; The origin of the Universe, postulated by Georges-Henry Lamaître between 1927 and 1933. The Cosmic Microwave Background was predicted in 1948 by Ralph Alpher and Robert Herman, they calculated that it should have by now cooled down to some 5° Kelvin (0° K = -273° C, 5° K = -268° C).

The images below were created from the Cosmic Background Explorer (COBE) satellite's Differential Microwave Radiometers (DMR) 4-year data products.

In the images, the blue and red spots correspond to regions of greater or lesser density in the early Universe, 300,000 years after the Big Bang itself. These relics record the distribution of matter and energy in the early Universe before the matter became organized into stars and galaxies.

While the initial discovery of variations in the intensity of the CMB (made by COBE in 1992) was based on a mathematical examination of two years of data, the new picture of the sky from the full four-year mission gives an accurate visual impression of the data.

These maps have been smoothed with a 7 degree beam, giving an effective angular resolution of 10 degrees.
At this angular scale, the signal-to-noise ratio is sufficient (~2 per 10 degree patch) to portray for the first time an accurate visual impression of the Cosmic Microwave Background (CMB) anisotropy.
An all-sky image in Galactic coordinates is plotted using the equal-area Mollweide projection.
The plane of the Milky Way Galaxy is horizontal across the middle of each picture. Sagittarius is in the center of the map, Orion is to the right and Cygnus is to the left.

The image represents DMR data from the 53 GHz band on a scale from 0° to 4° K, showing the near-uniformity of the Cosmic Microwave Background (CMB) brightness (top), then on a scale intended to enhance the contrast due to the dipole component (middle), and following subtraction of the dipole component (bottom).

The dipole, a smooth variation between relatively hot and relatively cold areas, from the upper right to the lower left, is due to the motion of the Solar System relative to distant matter in the Universe. The signals attributed to this variation are very small, only one thousandth the brightness of the sky.

This is the COBE-DMR "Map of the Early Universe".
This false-color image shows tiny variations in the intensity of the Cosmic Microwave Background measured in four years of observations by the Differential Microwave Radiometers (DMR) on the NASA's Cosmic Background Explorer (COBE).
The features traced in this map stretch across the visible Universe: The largest features seen by optical telescopes, such as the "Great Wall" of galaxies, would fit neatly within the smallest feature in this map. (Caption courtesy of Dr. Charles L. Bennett)

The COBE datasets were developed by the NASA Goddard Space Flight Center under the guidance of the COBE Science Working Group and were provided by the NSSDC.

Related Links:

• Cosmology (Royal Greenwich Observatory Leaflets)
• Distant Exploding Stars Foretell the Fate of the Universe (Background Information from the STScI)
• Hubble Pinpoints Distant Supernovae (Background Information from the STScI)

Outside ARVAL's Web site:

Main sources for these pages:

• Cosmic Background Experiment (COBE) DMR Images
• CMB Astrophysics Research Program (Lawrence Berkeley National Laboratory)

Recent Research:

• Smoot Cosmology Group
• Lawrence Berkeley National Laboratory
• Supernova Cosmology Project (Lawrence Berkeley National Laboratory)
• Cosmology with Supernovae: The High-Z Supernova Search High-Z SN Search
• Wilkinson Microwave Anisotropy Probe (WMAP)
- New results: March 2006
• To the authors of the information in this section;
  John C. Mather and George F. Smoot, Nobel Prize in Physics 2006 (Nobel Foundation)
  See The Nobel Prize in Physics 2006 (.pdf)

Others:

• Berkeley Cosmology Group
• The Cosmic Microwave Background, by Douglas Scott
• NASA - Origins Program
• STScI - Origins Education Outreach
• Wayne Hu, Cosmic Microwave Background Tutorials

Updated: October 3 '06

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Back to: ARVAL's Gallery (The Cosmic Microwave Background - A Relic from the Origin of the Universe)