Hubble, the expansion of the universe, and its consequences.

To mark the 131st anniversary of Edwin Hubble’s birthday on Friday, November 20, 2020, we will examine how Hubble discovered other galaxies besides our own, as well as how he proved that the universe is expanding. We will see how, starting from this remarkable discovery, we arrived at the Big Bang theory and, from there, at the modern cosmological view of the birth and evolution of the Universe. Finally, we will dispel misconceptions surrounding the Big Bang Theory by answering a series of questions, such as: • What does it mean that the universe is expanding? Do galaxies move through space? • What does the Big Bang theory describe? • What kind of explosion (wasn’t) the Big Bang? • What was it that exploded? • Where did this explosion occur? • What is the difference between expansion in space and the expansion of space itself? • Is it possible for galaxies to move away from each other at speeds greater than the speed of light? • Can we observe the entire Universe? What is the difference between the observable Universe and the entire Universe? • What is the age and size of the observable Universe? Texts: Alexis Delivorias, Ph.D. Physics, Dimitris Stathopoulos, Ph.D. Astrophysics Presentation: Dimitris Stathopoulos, Ph.D. Astrophysics