Cosmic Microwave Radiation Background


The cosmic microwave radiation background can be termed as the most studied bit of evidence that explains the Big Bang. It is a form of isotropic/electromagnetic radiation covering the universe left over from the earlier stages of development of the universe. With the big bang theory being one of the most comprehensive theories in figuring out the origins of the universe and its approximate age, the cosmic microwave radiation background plays a fundamental role in understanding the big bang.

Somehow it is more reliable since it gives scientific evidence and observations that support it. From meticulous studies of the cosmic microwave background radiation to the unearthing of planets around other heavenly bodies, to investigate the impact of galaxies aged billions of years, and exploration expeditions to other, astronomers are fast structuring a representation of the cosmos and its development process by which it is evolving with immense aspects than ever before. (Choi, Kim, & Son, 2005)

Section 1: Cosmic Microwave Radiation Background (CMRB)

The Cosmic Microwave Radiation Background also known as CMRB, CRB or CMB is the remnant left behind (afterglow) after occurrence of the big bang 13.7billion years ago “cooled to a faint whisper in the microwave spectrum by the expansion of the Universe for 15 billion years (which causes the radiation originally produced in the big bang to redshift to longer wavelengths).”

The Big Bang theory and other established cosmological theories put forward, argue that the universe is neither never-ending nor eternal and the discovery of CMRB is a milestone in astrophysics in determining the big bang model/theory. Astronomers Arno Penzias and Robert Wilson winners of the 1978 Nobel Prize discovered evidence of Cosmic Radiation Microwave Background in 1965 while at work at Bell Telephone Laboratories in Murray Hill, New Jersey which they alleged it had to have been discharged close to 500,000 years after the big bang occurred…

…when electrons and protons in the primordial plasma— the hot, dense soup of subatomic particles that filled the early universe—first combined to form hydrogen atoms. Because this radiation provides a snapshot of the universe at that time, it has become the Rosetta stone of cosmology. (Caldwell & Kamionkowski 2001, Astronomy 162, 2010)

In reality George Gamow, Ralph Alpher, & Robert Herman had envisaged in 1948 that the cosmic microwave radiation background as a leftover of the development of the early cosmos.

Accurate measurements of cosmic microwave background radiation are critical to astronomy, since any proposed representation of the cosmos should make clear this radiation. The CMRB radiance is at a temperature of 2.725 K no matter the bearing observed in the sky, and its spectrum ‘a thermal blackbody’ hits the highest point of its microwave range frequency of 160.2 GHz thus it derives its name ‘the cosmic microwave background radiation’ from this characteristic. It is a pale glow and referred to as a background of microwave photons due to the fact that it does not linked to any particular star, cloud, galaxy or any other object in the universe(Seeds & Backman 2009).

The CMRB’s glow has an “extremely precise pattern equal to that expected if a fairly uniformly distributed red-hot gas is expanded to the current size of the universe”( Naselʹskiĭ, Novikov, & Novikov 2006). In the aftermath of the big bang as the universe cooled down, remnant radiation formed from the cooling of the radiation and plasma filling the expanding universe. This resulted to a formation of stable atoms which could no longer soak up the thermal radiation resulting to a transparent universe instead of an opaque fog with the existing photons proliferating constantly though they keep growing fainter and contain lesser energy, which is known as the CMRB ‘a black body spectrum’.

…In particular, the spatial power spectrum (how much difference is observed versus how far apart the regions are on the sky) contains small anisotropies, or irregularities, which vary with the size of the region examined. They have been measured in detail, and match what would be expected if small thermal variations, generated by quantum fluctuations of matter in a very tiny space, had expanded to the size of the observable universe we see today (Sánchez & Parijskij 2003).

The big bang is the only theory that has been able to explain the falactuqations despite diverse methods trying to create the common appearance of a black body spectrum. Consequently, the Big Bang is considered the most comprehensive explanation for the CMBR. ‘Hubble’s discovery that the universe is expanding in all directions and consequent discovery of the Cosmic Microwave Radiation Background, the remnant of some cataclysmic explosion billions of years ago have all helped to… generate scientific support to the big abng theory’(Germadnik 2001).

Section 2: Wilkinson Microwave Anisotropy Probe

What are astronomers now trying to measure with projects like WMAP?

The Wilkinson Microwave Anisotropy Probe (WAMP) is a powerful probe that is used to measure differences in temperatures that remained in the radiant heat after the Big Bang occurred which is commonly referred to as the Cosmic Microwave Radiation Background (CMRB) across the universe. The WMAP spacecraft mission was first initiated on June 30th, 2001 and is also known as the Microwave Anisotropy Probe (MAP), and Explorer 80.

It plays a pivotal role in measuring cosmic microwave radiation background which is fundamental to understanding the big bang theory consequently providing astronomers with approximate assumptions in their calculations of the age of the universe. Its main function is ‘mapping the temperature and polarization anisotropies of the Cosmic Microwave Radiation Background (CMRB) on the full sky in 5 microwave bands (22, 30, 41, 60 and 94GHz)’ (Melchiorri & Rephaeli 2005).

Precise measurements of the CMRB have had a fundamental impact on astronomers calculations and deliberations on the age of the universe and how it was formed- big bang theory- thus the ability/ mission of the WAMP to produce high quality full sky maps of the CMRB with angular resolutions a factor of 30 better than that of the COBE ‘(Cosmic Background Explorer satellite developed to calculate the diffused infrared and cosmic microwave background radiation from the early Universe to the limits set by our astrophysical environment)’ (National Aeronautic and Space Administration 2010)

Astronomers are constantly trying to find ways of calculating the age of the universe so as not to find themselves in an impending crisis where there would be contradictions resulting in the theories and models used to calculate this. The WMAP satellite provides a solution to this impending predicament as it is able to measure/ determine in depth makeup of the cosmic microwave background fluctuations depending on current universe density, composition and rate of expansion. WMAP‘s accuracy of ascertaining parameters involved in holding up authenticity of the CMRB is more than 3% of the critical density of the CMRB, ‘in turn, knowing the composition with this precision, we can estimate the age of the universe to about 1%: 13.7 ± 0.13 billion years’(National Aeronautic and Space Administration 2010).

…Since the CMB radiation was emitted so long ago (and far away), it carries a great deal of information about the properties of our universe which can be measured in no other way. This early radiation was effected everywhere by the physics of matter within the bounds set by the parameters. So we have a large statistical sample of microwave radiation (across the whole sky) to help us determine these parameters. Because WMAP can measure the CMB patterns of radiation with tremendous accuracy, it accurately determines most of the basic parameters of cosmology (National Aeronautic and Space Administration 2010).

The theories in place especially the big bang theory provide an abundance of opportunity for deliberations and questions on the actual composition and characteristics of the universe that Astronomers and cosmologists feel are imperative and should be answered by support of evidence and interpretation of the universe and not merely based on speculation. These parameters include things such as:

  • Whether the universe will continue to expand or may reach a point and collapse?
  • Does exotic matter dominate the composition of the universe?
  • When were the first galaxies formed and how?
  • Whether the expansion rate of the universe is accelerating or decelerating?
  • The shape of the universe?

Therefore with the above parameters in mind, data from the WMAP satellite enables astronomers observe and study the CMRB and come up with conclusions that give more precedence to the big bang theory with an uncertainty of 1% (D’Onofrio & Burigana2009). The ability of the Wilkinson Microwave Anisotropy Probe to detect the remnant glow of the early universe despite it losing energy and becoming faint is an immense achievement for astronomers and the big bang theory in particular.

Section 3: Aims of These Projects

The major aim of the Wilkinson Microwave Anisotropy Probe is to offer accurate and precise information/data on the fluctuating temperatures of the remnant glow after creation of the universe as a result of the big bang. These projects aim to shed light on a number of areas in the study of the cosmos which include: age of the universe, shape of the universe, composition of the universe, and rate of expansion of the universe.

…If a reliable set of parameter standards can be established, and the implied density and gravitational potential perturbations at recombination evolve into the observed large-scale structure under the influence of understood physical processes, then we will have learned much about the universe. If no consistent set of parameters can be found, or if the CMB data and the large-scale structure data disagree, then we will have new physical processes to find and understand. In any case, the study of the CMB will lead to a much better understanding of the universe. (Wright 2006)

Age: Determining how old the universe is an how it was formed is a constant headache for astronomers as they are seeking accurate calculations and models to be able to give a precise figure. In that case these projects are key in that they aim to be able to shed more light on the data produced for calculation and verification of how old the universe might actually be.

Shape: measurements from the WMAP are more precise and astronomers intend to determine the shape of the universe. For example: the vivid CMRB fluctuations would be close to 1 degree across if the universe was a flat surface but on the other hand if it was closed they would be 1.5 degrees across.( Freedman 2004)


Astrophysics and astronomy is a continuous and wide subject thus the need for more detailed and precise data to provide frameworks for present theories and future calculations and deliberations on the subject of the universe. Astronomers should strive to be more efficient and base claims on evidence from the observation of the universe and not mere theories. As found out in this paper the mission set out by the Wilkinson Microwave Anisotropy Probe (WAMP) to measure the fluctuating temperatures of the Cosmic Microwave Radiation Background and has so far been proved to be more accurate than the COBE- Cosmic Background Explorer satellite.

It has higher resolutions and a precision of more than 3% of the critical density of the CMRB. The WAMP has been able to shed light on some parameters put forward by the big bang theory by providing extensive data on the CMRB. It has been able to answer queries on the behaviour and structure of the universe such as its age, rate of expansion, shape, acceleration and deceleration, matter/energy and composition, life of the universe and finally the fate of the universe.

Accurate and precise calculations are more than mandatory for astronomers to be able to support their theories. As a result of responding to much of the existing issues, the study of the CMRB in addition to data collected from the WMAP will probably tip astrophysicists towards novel and unfathomable queries about the character of our universe. The CMRB contains a massive amount of data and information about the components of the universe and thus the more need for it to be studied closely as it is the closest supporting evidence of the big bang theory that explains the origins of the universe as we know it today.

Cosmic microwave radiation background.
Figure 1: cosmic microwave radiation background.

We can only see the bottom surface of clouds in our atmosphere because that’s where light no longer scatters off the water molecules in the cloud. Similarly, we can only see clearly into space to where the microwave background was last scattered off the electron haze in the early universe.

WMAP’s view of the universe from the first seven years of data.
Figure 1: WMAP’s view of the universe from the first seven years of data. NASA/WMAP Science Team. 

Reference list

Astronomy 162: Stars, galaxies and cosmology. 2010. Web.

Caldwell, R & Kamionkowski, M 2001, ‘Echoes from the Big Bang’ Scientific American, 2010. Web.

Choi, K, Kim, J, & Son, D 2005, Particles, strings, and cosmology: 11th International Symposium on Particles, Strings, and Cosmology, PASCOS 2005, Gyeongju, Korea, Springer, New York, NY.

D’Onofrio, M & Burigana, C 2009, Questions of Modern Cosmology: Galileo’s Legacy, Korea.

Freedman, W 2004, Measuring and modeling the universe, Cambridge University Press, New York, NY.

Germadnik, M 2001, How do we know the age of the universe, The Rosen Publishing Group, New York, NY.

Melchiorri, F & Rephaeli, Y 2005, Background microwave radiation and intracluster cosmology, IOS Press, Fairfax, VA.

Naselʹskiĭ, P, Novikov, D& Novikov, I 2006, The physics of the cosmic microwave background, Cambridge University Press, New York, NY.

National Aeronautic and Space Administration: Wilkinson Microwave Anisotropy Probe. 2010. Web.

Sánchez, N & Parijskij, N 2003, The early universe and the cosmic microwave background: theory and observations, Springer, New York, NY.

Seeds, M & Backman, D 2009. Astronomy: The Solar System and Beyond, Cengage Learning New York, NY.

Wright, E 2006, ‘Cosmic Microwave Background’, Encyclopedia of Astronomy & Astrophysics.