Science and technology is part of UPSC mains GS-3 syllabus. It is one of the most neglected subject of UPSCMains. For this the IAS aspirants should compulsoryly  give atleast take up this topic twice a week. Also tthey should be aware of current affairs related to oscience and technology. Make notes for both factual and conceptual part.


  • Big Bang Theory
  • Experiment
  • The first few moments
  • Expansion of Universe
  • Missions to study Big Bang


Big bang theory is the modern theory in terms of the origin of earth. If you remember how nebular hypothesis is the early theory and in that we read about the formation of sun, stars, planets, asteroids etc, in Big Bang theory scientists decided – “let’s look at the larger picture, let’s find out how the universe came into existence”. So whenever you hear the word Big Bang, you must immediately recollect that it is about the expanding universe hypothesis. So basically it is an effort to explain what happened at the very beginning of our universe.

Many discoveries in astronomy and physics have shown beyond a reasonable doubt that our universe did in fact have a beginning. Prior to that moment there was nothing; during and after that moment there was something that is our universe. The big bang theory is an effort to explain what happened during and after that moment.

So how did we come to this conclusion? In 1920, Edwin Hubble, provided evidence that the universe is expanding. Edwin Hubble is the same guy after whom the famous Hubble space telescope is named. He said, As time passes, galaxies move further and further apart.


There is an experiment associated with it. Take a balloon and mark some points on it to represent the galaxies. Now, if you start inflating the balloon, the points marked on the balloon will appear to be moving away from each other as the balloon expands. Similarly, the distance between the galaxies is also found to be increasing and thereby, the universe is considered to be expanding. But i want you to also notice this, besides the increase in the distances between the points on the balloon, the points themselves are expanding. But in reality the scientists had no real evidence about the expansion of galaxies, but they do believe that the distances between galaxies is increasing. Hence we can say that the balloon example is only partially correct.

The first few moments

After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, including photons, electrons, protons and neutrons.Though simple atomic nuclei formed within the first three minutes after the Big Bang, thousands of years passed before the first electrically neutral atoms formed. The majority of atoms that were produced by the Big Bang are hydrogen, along with helium and traces of lithium.

Expansion of universe

It had always been assumed that the matter of the Universe would slow its rate of expansion. Mass creates gravity, gravity creates pull, the pulling must slow the expansion. But supernovae observations showed that the expansion of the Universe, rather than slowing, is accelerating. Something, not like matter and not like ordinary energy, is pushing the galaxies apart. This “stuff” has been dubbed dark energy, but to give it a name is not to understand it. Whether dark energy is a type of dynamical fluid, heretofore unknown to physics, or whether it is a property of the vacuum of empty space, or whether it is some modification to general relativity is not yet known.

Missions to study Big Bang

  • Cosmic Background Explorer (COBE) : NASA has launched two missions to study the cosmic background radiation, taking “baby pictures” of the Universe only 400,000 years after it was born. The first of these was the Cosmic Background Explorer (COBE).

  • Wilkinson Microwave Anisotropy Probe (WMAP):The second mission to examine the cosmic background radiation The Wilkinson Microwave Anisotropy Probe (WMAP) is a NASA Explorer mission that launched June 2001 to make fundamental measurements of cosmology -- the study of the properties of our universe as a whole. WMAP has been stunningly successful, producing our new Standard Model of Cosmology.

  • Planck: A third mission, Planck, led by the European Space Agency with significant participation from NASA, was launched in 2009.  Planck is making the most accurate maps of the microwave background radiation yet. With instruments sensitive to temperature variations of a few millionths of a degree, and mapping the full sky over 9 wavelength bands, it measures the fluctuations of the temperature of the CMB with an accuracy set by fundamental astrophysical limits.


Today NASA spacecraft such as the Hubble Space Telescope and the Spitzer Space Telescope continue Edwin Hubble’s work of measuring the expansion of the Universe.

To study Science and Technology for UPSC you dont need to have science background. Its necessary to understand hoe India is developing its science and technology. To read more articles on Science and technoly click here