First Light – CMBR

Celebrating IYL 2015

     If you look at the modern periodic table you will find hundred and eighteen elements listed in it. Out of this, ninety four elements occur naturally.  All these elements can be found on Earth (exceptions are there).  Elements are building block of things that you see around you.  Whether it’s a human, animal, tree, building, roads, bridges, monuments, mountains, etc, everything is made up of elements.  But the question that comes to our mind is who brought all these elements on the Earth?  How are they formed?  The answer is… all these elements are formed inside a star.  Yes, in a sense, everything that you see around is cooked inside a star!  Richard Feynman, a famous physicist once said that, the stuff which we are made was once cooked in a star and spit out.

      The entire universe comprises trillions of trillions stars which cooks the matter that we see around us.  The next question that arises is how do these stars form?  Well, these kinds of questions will go on….. it’s a never ending process. But then, where do we begin?

Yes, we begin at the beginning.
We begin at the Big Bang!

Big Bang
Artist view of Big Bang before the explosion.

     The universe which includes stars, galaxies, nebulae etc. is expanding for billions of years.  If you look back, somewhere in the past there must exist a time where the entire universe is concentrated in a point of high density (infinite density).  According to the accepted theory, this high density state of a point, exploded violently, creating the universe that we see today.  This is the Big Bang theory proposed by Edwin Hubble in the year 1929.  The explosion that we consider in Big Bang is not at all a violent explosion, in fact it is one of the silent explosions that you can ever think of and it is neither big nor bang!  This is just a name given to the theory.  The reason is this, the space, time, sound, matter, elements and more importantly the light that we feel and experience today was created after Big Bang!  Big Bang is just an expansion of a point of infinite density, nothing more that.  But then, how do we verify this theory?

     If this kind of an expansion has happened in the past, then we must be able to detect, outer surface of the expanding sphere which contains the information of big bang in the form of light.  According to the theory, this sphere of light should uniformly exist all over the space. In a sense we have to detect the first light from the big bang.  This is called background radiation of the Big Bang.  If we succeed, it confirms the theory Big Bang.

   In the year, 1960 two astrophysics namely Dickey and Pebbles were working on the challenge of finding background radiation of the Big Bang.  They came to the conclusion that, since universe is expanding from billions of years, the energy of the photons of background radiation must be less because of the expansion in space.  (Expanding Universe:  The space and time fabric between the galaxies expand.  The light or the photon which travels in this fabric also expands.  When it expands the energy of the photon becomes less – this is predicted by Einstein’s General Theory of Relativity) When they did the calculation by using Wien’s Displacement law, they found that photon’s energy lies in the microwave region of light.
Few miles away from this group of scientist there were two more researchers from Bell Laboratory namely Penzias and Wilson designing the Horn antenna for radio astronomy.  They were trying to remove the background noise in the antenna which is detected by the detector.  No matter how much they tried they were unable to remove the background noise even-though they replaced the detector for many times.  Interestingly the detector was detecting the noise in all the direction and at all times of the day.  After their unsuccessful attempt of trying to remove this noise, they come to the conclusion that, this signal is not a noise, it is actually coming from outer space.

     Later it turned out that the noise of Penzias and Wilson’s horn antennae was actually the background radiation of Big Bang that Dickey and Pebbles were searching for!  Yes, it was an accidental discovery by two researchers from Bell Laboratory who have no idea about background radiation.  All they did was they tuned their antennae to receive a microwave radiation.  The detector was detecting first light from the Big Bang but Penzias and Wilson thought it was noise!!  The temperature of the background radiation was 3 kelvin and it was in perfect agreement with the measured value from the theory.  This is famously called as 3 kelvin black body radiation curve or 3 K curve.   Both of them were awarded noble price in physics in the year 1978 for their accidental discovery of Background Radiation.  Press Release from Bell Labs can be seen here. This observation confirms Big Bang theory.  (Big Bang theory is still a debatable theory for other reasons).

Horn Antenna
Penzias and Wilson in front of Horn Antenna

     Today we have some of the sophisticated scientific instruments in the on-board satellites which are revolving around the Earth.  WMAP (Wilkinson Microwave Anisotropy Probe) has mapped the background radiation.  The first light from the Big Bang is here….

CMBR – Cosmic Microwave Background Radiation by WMAP

The Light which is the sole responsible for life on earth was actually began its journey 13.5 billion years ago.

Through light on some atoms for billions of years, eventually you have life!

Image Details:
First Image: International Year of Light and Light Based Applications – 2015 Logo
Second Image: S. Harris Cartoon
Third Image : Bell Labs
Fourth Image:
APOD Images, March 25, 2013
Year 2015 is celebrated as International Year of Light and Light Based Technology by UN as a global event.  This year mark the 150th anniversary of Maxwell’s Equations by James Clerk Maxwell, the man who unfolded the secret of nature and answered what light is made up of. 

More Information about IYL 2015
UN Anniversaries
IYL – 2015 Home Page
IYL – 2015 Blog

Upcoming Topics for IYL 2015

  • Elusive Particles of the Universe
  • Biological Industry – Photosynthesis
  • Principe, Africa – 1919 TSE
  • Copy of Earth – Extraterrestrial Planet
  • ದೀಪವು ನಿನ್ನದೆ ಗಾಳಿಯು ನಿನ್ನದೆ ಆರದಿರಲಿ ಬೆಳಕು
  • Let there be light – Newton, Maxwell, Hertz and Einstein

Viswa Keerthy S



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