Did the universe have a beginning, or is it eternal? For centuries most philosophers thought the latter.
Aristotle, for example, reasoned from his own limited logic that the universe never had a beginning. However, from late antiquity to the Middle-Ages, thinkers with a Judeo-Christian worldview or theological position disagreed. Maimonides, Augustine, Thomas Aquinas, Bonaventure and others stood firmly on creation ex-nihilo: the understanding that the universe had a beginning.
Later other God-believing philosophers saw a beginning to the universe in time, but also saw infinite space. These included Descartes and Newton. Newton’s laws of gravitation led him to believe that the universe must be spatially infinite, or else it would collapse on itself.
Early in the nineteenth century German astronomer Heinrich Olbers presented a mystery involving the night sky. He said that the universe could not be spatially infinite, or the night sky would be a solid mass of light. Various theories attempted to answer this paradox, but it was American poet Edgar Allen Poe who in 1848 came up with the most powerful solution. He suggested that the immensity of the universe has not allowed all light to reach us yet. Poe’s idea demonstrated, as physicists only came to agree seventy-five years later, that the universe is of a finite age. Poe also proposed that the universe began with a “primordial particle” and expanded spherically in all directions: an idea well ahead of its time.
At the beginning of the twentieth century few astronomers doubted an infinite age of the universe. They accepted Newtonian physics, which included infinite space. If space is infinite in expanse, then it made sense that it is also eternal. From the late nineteenth century geologists began to deduce very old ages for the earth’s rocks, and uniformitarianism lent credence to the idea of an infinite age for the universe. This was all very attractive to early twentieth-century scientists who were pleased to be able to dispense with God from their considerations. If there were no beginning, there was no need for a Beginner.
Meyer discusses the debate raging among astronomers over the last few hundred years over the size of the universe. The understanding was at first that our galaxy was the entire universe. At the beginning of the twentieth century two prominent astronomers, Harlow Shapley and Heber Curtis openly debated the question of whether fuzzy lights seen far away were just gaseous material, or other galaxies beyond our own. Meyer goes into some technical detail on the issues he’s covering here, perhaps intentionally demonstrating his own grasp on numerous scientific disciplines. He doesn’t make it too difficult for the likes of me, though, my understanding of science being quite limited.
Was there more to the universe than our galaxy? What were the distances involved between celestial objects? American astronomer Edwin Hubble, with his huge telescope and sharp mind, along with the findings of earlier scientists, helped solve these debates. Vesto Slipher, who lived from the nineteenth into the twentieth centuries, had discovered the red shift of light coming from distant nebulae, and knew, as the Doppler Effect on sound is known, that this indicated a movement of celestial bodies away from us. Hubble used this knowledge to establish two profound facts. He found that certain objects thought to be within our galaxy were in fact other galaxies beyond ours. But another, far more significant finding was that more distant galaxies recede at faster rates.
Hubble deduced a linear relationship between recessional velocity and distance. This suggested strongly that the universe is undergoing an expansion like a balloon being blown up in all directions from a singular beginning. In turn the discovery posed a deeply philosophical conundrum to the scientific community: it implied that the universe had a beginning after all.