Unlocking the Cosmos: Explore Stephen Hawking’s Groundbreaking PhD Thesis on Expanding Universes | The Times of India

Stephen Hawking, a renowned theoretical physicist, wrote his PhD thesis, "Properties of Expanding Universes," in 1966 at the University of Cambridge. This groundbreaking work helped shape our understanding of the universe and laid the groundwork for his later contributions to black holes and cosmology.

In the 20th century, major strides were made in understanding the universe. Albert Einstein introduced the General Theory of Relativity in 1915, explaining how gravity curves space-time. Edwin Hubble’s observations in the 1920s revealed that the universe is expanding, leading to the Big Bang theory. Yet, questions about singularities—points where gravity becomes infinite—remained.

Hawking’s thesis aimed to tackle these challenges. Guided by his supervisor, Dennis Sciama, he explored how the universe evolves and the role of singularities. His work was complex but important, using mathematical models to delve into several key areas:

1. Singularities: Hawking showed that if the universe adheres to general relativity and contains sufficient matter, singularities are inevitable. This reinforced the idea that the universe began from a singularity, supporting the Big Bang theory.

2. Causality: He examined how an expanding universe maintains causality, meaning events happen in a cause-and-effect order. His mathematical models indicated that time loops or faster-than-light communication are unlikely under general relativity.

3. Matter Distribution: Different arrangements of matter impact the universe’s expansion. Hawking analyzed scenarios with uniform and clumped matter, revealing how galaxies might have formed from a smoother early universe.

4. Boundary Conditions: He considered how the universe’s shape affects its expansion. While he later proposed a “no-boundary” condition, his thesis initiated discussions about the universe’s topology.

Hawking utilized advanced mathematics, including Einstein’s equations, to frame his insights. His research contributed to the development of theories about singularities in general relativity, leading to significant collaborations, notably with Roger Penrose. Together, they established the Penrose-Hawking Singularity Theorems, asserting that singularities are a natural part of the universe’s evolution.

Hawking’s work also laid the foundation for his later investigation of black holes, culminating in his striking hypothesis of Hawking radiation—the idea that black holes can emit radiation and gradually lose mass.

In 2017, when Cambridge made his thesis available online, it was downloaded over two million times shortly after. Reflecting on this, Hawking encouraged others to look up at the stars, emphasizing the wonder of our universe.

Today, Hawking’s thesis remains influential, shaping ongoing conversations in theoretical physics. His exploration of singularities, causality, and cosmic expansion continues to inspire scientists. More than five decades later, "Properties of Expanding Universes" stands as a testament to Hawking’s intelligence and curiosity, cementing his legacy as one of the greatest thinkers in science.

For more on Hawking’s work and its impact, you can explore resources like NASA’s Cosmic Perspectives which highlight ongoing research in astrophysics and cosmology.

Check out this related article: Unlocking the Universe: Euclid’s Stunning Deep Field Images Reveal 26 Million Galaxies

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