Jayant V. Narlikar is Emeritus Professor at the Inter-University Centre for Astronomy and Astrophysics, Pune, India. Known for his work on cosmology, Narlikar served as President of the Cosmology Commission of the International Astronomical Union (1994-97). Other books by Professor Narlikar include An Introduction to Cosmology (now in its third edition, 2002) and Current Issues in Cosmology (with Jean-Claude Pecker, 2006), both with Cambridge University Press. Geoffrey Burbidge is a Professor in the Department of Physics at the University of California, San Diego. He is best known for his work on stellar nucleosynthesis and quasi-stellar objects. Professor Burbidge has been the recipient of several awards, most recently the Gold Medal of the Royal Astronomical Society with Margaret Burbidge. He co-authored A Different Approach to Cosmology (with Jayant Narlikar and Fred Hoyle, Cambridge University Press, released in paperback in 2005).