Nobel Prize in Physics has been conferred to three people: Michel Mayor and Didier Queloz for discovering for the first time a planet outside our solar system orbiting a Sun-like star, the other half would go to James Peebles, for his contribution to physical cosmology

James Peebles Contributions

  • He realised that measuring the CMB’s temperature could provide information about how much matter had been created in the Big Bang. 
  • He also saw that the release of this light played a role in how matter could form clumps creating what we now see as galaxies.
  • Peebles’ role in understanding Dark matter
  • Before Peebles intervened, the missing mass was attributed to neutrinos. Peebles instead said this is due to a hitherto unknown type of “dark” matter particles
  • However, while they could “see” a portion of this mass, a large part of it could not be seen. Hence the mass missing from view was named “dark” matter


Background info

Cosmic Microwave Background(CMB)

  • About 400,000 years after the Big Bang, the universe expanded and cooled to a few thousand degrees Celsius. This caused it to become transparent, allowing light to pass through it. 
  • This ancient afterglow of the Big Bang, the remnants of which still can be observed, is known as the cosmic microwave background (CMB).
  • The CMB consists of light in the microwave range because the expansion of the universe stretches the light so much. 
  • Microwave radiation is invisible light. The CMB was detected first in 1964, winning for its discoverers a Nobel Prize in 1978.

Dark Matter

  • In 1998, it was discovered that the universe is expanding and that this expansion was gaining speed or accelerating. There had to be an “invisible” energy that was driving this. 
  • Calculations showed that this dark energy so called because it did not interact with the observed mass, makes up about 70% of the universe.
  • By measuring the speeds of rotating galaxies, scientists were able to see that a lot of mass needed to be there that would hold the galaxies together with the strength of their gravitational attraction.
  • Even though this matter is all around us, close as well as far away, we only feel it through its gravity, but we cannot see it through other interactions. 
  • This is because it does not interact with light


Kepler Space Telescope

  • This Mission of NASA is specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone
  • It will determine the fraction of the hundreds of billions of stars in our galaxy that might have such planets.