The End of the Universe - with Geraint Lewis

The speaker, a cosmologist from the University of Sydney, introduces the concept of understanding the Universe's evolution from its formless beginnings to its current structured state. The focus is on taking a journey not through space, but through time, starting from the Big Bang and speculating about the Universe's future as it ages.

The speaker emphasizes Earth's uniqueness as the only known planet with indisputable evidence of life. Despite the vast number of planets in the Universe, Earth stands out. The discussion also touches on the difficulty of defining life and the importance of energy in all life processes, highlighting the Sun as the ultimate source of energy for life on Earth.

The speaker discusses the significance of Isaac Newton's contributions to science, particularly his laws of motion and gravity, which laid the foundation for understanding the Universe's mechanics. The talk transitions to the advancements in telescope technology, enabling scientists to observe the Universe in greater detail and depth, leading to a more comprehensive understanding of cosmic evolution.

The speaker delves into the evolution of the Universe, from the smooth distribution of matter after the Big Bang to the formation of galaxies and stars. The process of star formation, the life cycle of stars, and the recycling of elements necessary for life are explained. The talk also touches on the construction of the Square Kilometre Array and the Wilkinson Microwave Anisotropy Probe, which have provided insights into the Universe's history.

The speaker explores the limitations of predicting the Universe's future, acknowledging the lack of telescopes that can see into the future and the imperfect understanding of physical laws, especially where quantum mechanics and gravity intersect. The discussion includes the potential for the Milky Way and Andromeda galaxies to collide, the eventual fading of distant galaxies from view due to the accelerating expansion of the Universe, and the challenges life may face in adapting to these cosmic changes.

The speaker describes the future collision between the Milky Way and Andromeda galaxies, resulting in the formation of a new galaxy called Milkomeda. The process involves initial star collisions, the creation of hot blue stars, and the eventual fading of these stars. The speaker also discusses the Sun's life cycle, its eventual transformation into a red giant, and the impact on Earth's future.

The speaker talks about the life cycle of stars, from the blue giants that live fast and die young to the red dwarf stars that live for trillions of years. The discussion includes the continuous dying of stars, the fading of the galaxy, and the challenges for life forms to adapt to the energy scarcity in the Universe. The speaker also introduces the concept of a Dyson sphere as a potential solution for future civilizations to harness energy from stars.

The speaker speculates on the ultimate fate of matter in the Universe, including the stability of atoms and the potential decay of protons over an incredibly long timescale. The talk explores the implications for life in the Universe, the struggle for energy, and the possibility of harnessing energy from black holes. The speaker also introduces the concept of the heat death of the Universe, where no usable energy remains.

The speaker concludes with speculative ideas about the Universe's future, including the possibility of the Universe changing its energy state and creating new universes. The discussion encompasses the potential for life to continue in these new universes and the philosophical implications of an endless cycle of universes and life. The speaker leaves the audience with a hopeful vision of the Earth in 7 billion years.