Loeb: One experiment is to detect gravitational radiation, ripples in space time that were generated by the process of inflation, as long as it occurred early enough. The gravitational waves polarize the cosmic microwave background in a unique way for which people are searching.
I should also make another comment. Inflation makes specific predictions about the statistical properties of the density perturbation of matter in the universe, which are consistent with all existing data. There is a certain volume of space that we can actually observe. This is a sphere around us that has a radius which is equal to the distance that light can travel since the Big Bang. That’s the observable universe. You can ask which fraction of that observable volume was mapped so far. The answer is just a small fraction, about a tenth of a percent. So we still have 99.9 percent of the observable volume to observe and improve our tests of inflation. That will be very exciting in the coming decade.
A & S: Why now, at this point in the scientific understanding of the early universe, did you decide to publish a book explaining the current beliefs about how stars and galaxies form?
Loeb: The year 2010 marks a major transition point in studies of the first stars and galaxies. Until now most of the research has been theoretical. The next decade will bring about a new generation of large telescopes with unprecedented sensitivity that promise to supply a flood of data about the infant universe during its first billion years after the Big Bang. Among the new observatories are the James Webb Space Telescope, the successor to the Hubble Space Telescope, and three extremely large telescopes on the ground, ranging from 24 to 42 meters in diameter, as well as the new arrays of dipole antennas operating at low radio frequencies. The fresh data on the first galaxies and the diffuse gas in between them will test existing theories about the formation and radiative effects of the first galaxies, and might even reveal new physics that has not yet been anticipated. This emerging interface between theory and observation will constitute an ideal opportunity for students considering a research career in astrophysics or cosmology. Since this is an ideal time to introduce new researchers to the field, I decided to write a book that summarizes the fundamental principles and theoretical ideas from the perspective of my own work over the past two decades.