Who first proposed the Big Bang Theory?

The Big Bang Theory was first proposed by Georges Lemaître, a Belgian priest and astronomer, in the 1920s. He suggested that the universe began from a "primeval atom" or a single point that exploded and expanded, which laid the groundwork for what we now call the Big Bang Theory. Lemaître's ideas were significant as they combined both scientific inquiry and philosophical considerations about the origins of the universe. His work came at a time when the understanding of the universe's structure was evolving, and he was the first to describe how this expansion process might have occurred. This contribution was crucial in shaping modern cosmology, explaining not just the universe's beginnings but also how it has developed over time.

The other figures mentioned, while prominent in the field of physics and cosmology, did not originate the Big Bang Theory. Albert Einstein is best known for his theory of relativity, which transformed our understanding of space and time but did not propose the Big Bang. Niels Bohr made foundational contributions to quantum mechanics, not to cosmological theories. Stephen Hawking advanced our understanding of black holes and the nature of the universe but worked within the framework established by earlier scientists like Lemaître.