Evolution of Universe after the Big Bang

Nobel Prize for Physics

• This year’s Nobel Prize for Physics recognizes research that helps us understand our place in the universe.
• Canadian-American cosmologist James Peebles, 84, won one-half of the Prize for his theoretical work helping us understand how the universe evolved after the Big Bang.
• The other half went to Swiss astronomers Michel Mayor, 77, and Didier Queloz, 53, for their discovery of an exoplanet that challenged preconceived ideas about planets.

How the universe evolved

• Modern cosmology assumes that the universe formed as a result of the Big Bang.
• In decades of work since the 1960s, Peebles used theoretical physics and calculations to interpret what happened after.
• His work is focused largely on Cosmic Microwave Background (CMB) radiation, which is electromagnetic radiation left over from the early universe once it had cooled sufficiently following the Big Bang.
• Today, CMB can be observed with detectors.

Nobel Prize: It’s never too late

• When it was observed for the first time in 1964 by radio astronomers Arnold Penzias and Robert Wilson —who would go on to be awarded the 1978 Physics Nobel — they were initially puzzled.
• They learnt later that Peebles had predicted such radiation.
• Peebles and colleagues have correlated the temperature of this radiation with the amount of matter created in the Big Bang.
• This was a key step towards understanding how this matter would later form the galaxies and galaxy clusters.
• From their work derives our knowledge of how mysterious the universe is — just 5% known matter and the rest unknown, as dark matter (26%) and dark energy (69%).

Exoplanets

• The hunt for extraterrestrial life, if any exists, depends on finding habitable planets, mainly outside our Solar System.
• Today, exoplanets are being discovered very frequently — over 4,000 are known — which is remarkable progress from three decades ago, when not even one exoplanet was known.
• The first confirmed discoveries came in 1992, but these were orbiting not a star but the remains of one.
• The planet discovered by Mayor and Queloz in 1995 is 50 light years away, orbiting the star 51 Pegasus that is similar to our Sun.

51 Pegasus

• Called 51 Pegasus b, the exoplanet is not habitable either, but it challenged our understanding of planets and laid the foundation for future discoveries.
• It is a gas giant comparable to Jupiter, yet it very hot, unlike icy cold Jupiter; 51 Pegagsus b is even closer to its star than Mercury is to our Sun.
• Until then, gas giants were presumed to be cold, formed a great distance from their stars.
• Today, it is accepted that these hot gas giants represent what Jupiter would look like if it were suddenly transported closer to the Sun.