What's eating the universe? - with Paul Davies

The speaker begins by expressing gratitude for being part of the post-COVID effort and emphasizes the importance of face-to-face meetings. They extend a warm welcome to everyone, both present and joining online, and share a personal anecdote about their first visit to the Royal Institution decades ago. The speaker reminisces about their PhD on the arrow of time and the influence of Michael Faraday's words on their understanding of the universe. They also discuss their current residence in Arizona, known for its contributions to astronomy and the origins of cosmology.

The speaker delves into the history of cosmology, tracing its origins back to an observatory in Flagstaff, Arizona, built by Percival Lowell. Initially, the observatory aimed to find evidence of Martian canals, which were believed to be built by intelligent beings. However, the launch of NASA's Viking spacecrafts revealed Mars as a barren desert, debunking the canal theory. The speaker then introduces Vesto Slipher, an astronomer who studied the organization of the universe and discovered the redshift, suggesting that distant objects were moving away from us faster, which caught the attention of Edwin Hubble.

Edwin Hubble, using the 100-inch Mount Wilson telescope, further explored nebulae and confirmed they were galaxies like the Milky Way, millions of light years away. Hubble's observations led to the realization that the universe is expanding, a discovery he published in the New York Times in 1924. Despite the groundbreaking nature of this revelation, it did not immediately become a worldwide sensation. The speaker reflects on the implications of an expanding universe, questioning its trajectory and origin, and discusses the work of Georges Lemaître, who proposed the 'cosmic egg' theory, which was initially met with skepticism.

The speaker recounts the development of the Big Bang theory and the opposition it faced from astronomers like Fred Hoyle, who proposed the Steady State theory, suggesting the universe has no beginning or end. Hoyle's theory posited that new matter is continuously created as the universe expands. The term 'Big Bang' was initially used derisively by Hoyle during a BBC radio interview but eventually became the widely accepted term for the theory. The speaker also mentions the pivotal discovery of the cosmic microwave background radiation in 1964, which provided strong evidence for the Big Bang theory and effectively ended the dominance of the Steady State theory.

The speaker explores the concept of the universe's beginning with the Big Bang, which is considered the origin of space and time. They discuss the philosophical and theological implications of this idea, citing the views of Augustine, who proposed that the world was made with time, not in time. The speaker then introduces the quantum mechanics perspective, suggesting that the universe could have originated from a quantum event without a cause. This idea was developed by Jim Hartle and Stephen Hawking, who proposed a model where the universe emerges from a quantum state without boundaries.

The speaker discusses the discovery and analysis of the cosmic microwave background radiation (CMB), which provides detailed information about the early universe. They mention the work of Tim Bunch, a student who studied quantum fluctuations in the vacuum state of the universe. The speaker explains how these fluctuations are believed to have been imprinted on the universe during a period of rapid expansion, known as inflation, which occurred in the first split second after the Big Bang. This theory is supported by the statistical吻合 of theoretical predictions with observational data from the CMB.

The speaker reflects on the uniformity and precision of the universe's formation, suggesting that it was 'born in almost complete uniformity' with just the right variations to lead to complex structures like galaxies and life. They question whether the Big Bang was the ultimate origin of all physical things and introduce the concept of the multiverse, where our universe is one among many. The speaker discusses the implications of the multiverse theory, including the idea that each universe might have its own set of physical laws, and that our universe's laws may be conducive to life due to random chance.

The speaker addresses the discovery that the expansion of the universe is accelerating, a phenomenon attributed to dark energy. They explain that dark energy is a form of energy associated with empty space and acts as an anti-gravity force. The speaker also discusses the discrepancy between theoretical predictions and astronomical observations regarding the density of dark energy, which remains one of the greatest unsolved problems in cosmology. They conclude by discussing various scenarios for the end of the universe, including the 'big rip' and the possibility of the universe being consumed by black holes or swallowed by another universe.

In the concluding section, the speaker reflects on the comprehensibility of the universe and the human ability to understand it through science and mathematics. They touch upon the question of extraterrestrial life and the challenges in estimating the probability of life existing elsewhere in the universe due to the unknown factors involved in the origin of life. The speaker concludes with a quote from Alfred Wallace, emphasizing the importance of the scientific endeavor and the pursuit of knowledge.