Title: Wizards of the Early Universe

Speaker: Dr. Rome Samanta, Institute of Physics, Prague

Abstract: We are in an exciting frontier of modern cosmology, and we expect to know the early universe better than ever, thanks to the significant developments in Gravitational Waves and 21cm physics. Consider a deaf person with reasonably good eyesight. The person can learn a lot about the world by simply looking at things, or in scientific words, by studying light from the objects. If the person acquires the ability to hear or/and the eyesight becomes even better, a new realm of knowledge becomes accessible to the person. Historically, physicists relied primarily on light/electromagnetic radiation to study the universe and sometimes on subatomic particles such as light neutrinos. This has given us crucial information about the early universe. Nonetheless, unlike electromagnetic radiation, gravitational waves travel through the universe practically unimpeded with undistorted information about their origin. Therefore, they can uncover a new realm of knowledge that is as distinct as hearing from vision. On the other hand, 'better eyesight/ more lights' in the form of a 21cm signal of neutral hydrogen present abundantly in the early universe would enrich our existing knowledge of the processes that happened billions of years ago. In this talk, I shall discuss how these wizard (old but wise) signals can probe the early universe and cosmological puzzles such as matter-antimatter asymmetry, dark matter, etc.