Physics experiments that changed the world – with Suzie Sheehy

The speaker expresses gratitude for being back at the Royal Institution, a place with a rich scientific history. They introduce their book, 'The Matter of Everything,' and discuss the challenge of condensing a book's worth of stories into an hour-long lecture with demonstrations. The lecture begins with the turn of the 20th century, a time when physics was thought to be nearly complete, as quoted by Albert Michelson. The speaker aims to bring physics down to Earth and share personal stories from their journey of writing the book.

The speaker discusses the state of physics and society at the start of the 20th century, highlighting the belief that most grand principles had been established. They mention Albert Michelson's work on the non-existence of the ether and the general optimism about the future based on existing theories. The speaker then contrasts this with the significant changes that occurred in physics throughout the 20th century, setting the stage for the stories they will share from their book.

The speaker explores the societal changes that have occurred over the last century, comparing life expectancy, population growth, literacy rates, and GDP per capita from 1900 to the present. They emphasize the often-underappreciated role of physics alongside other factors like innovation, business, and education in driving these changes. The speaker also discusses the difficulty of predicting the future, even for physicists, using Lord Kelvin's incorrect predictions about transportation as an example.

The speaker describes the visions of the future from artists in 1900, highlighting the inaccuracies in their predictions about flying vehicles, architecture, and underwater living. They contrast these with the rapid advancements in information transfer and automation, and the lack of foresight regarding electronic means of automation. The speaker then transitions to discuss the role of physics in societal change, starting with Wilhelm Rontgen's discovery of X-rays in 1895.

The speaker recounts Wilhelm Rontgen's discovery of X-rays and his quiet, solitary nature. Rontgen's experiments with a Crookes tube led to the discovery of X-rays, which he quickly communicated to the medical community. The speaker highlights the rapid application of X-rays in medicine and photography, and the development of the CT scanner decades later, underscoring the long-term impact of Rontgen's discovery and the interdisciplinary nature of innovation.

The speaker shifts focus to JJ Thompson's work in Cambridge, where he explored the nature of cathode rays. Thompson hypothesized that these rays were particles and designed an experiment to measure their charge and mass. With the help of a glassblower, Thompson was able to create an apparatus that led to the discovery of the electron, a subatomic particle. This discovery was initially met with skepticism but later became foundational to our understanding of atomic structure.

The speaker reflects on the artisanal nature of scientific apparatus creation in the past, as exemplified by the work of glassblowers like Les Gamel. They highlight the skill and detail required to invent and create the equipment necessary for experiments. The speaker emphasizes the importance of recognizing the contributions of those who crafted the tools of scientific discovery.

The speaker brings attention to the significant yet often overlooked contributions of women in physics, such as Harriet Brooks. Brooks, a student of Rutherford, made foundational contributions to the understanding of radioactivity. Despite facing societal pressures and having to abandon her career after marriage, her work laid the groundwork for important discoveries. The speaker advocates for recognizing and celebrating the achievements of women in the field.

The speaker discusses the discovery of cosmic rays by Victor Hess and the subsequent development of the cloud chamber by CTR Wilson. The cloud chamber allowed for the visualization of radiation, leading to the discovery of new particles like the positron and the muon. The speaker also demonstrates the cloud chamber during the lecture, showing the tracks of charged particles and cosmic rays.

The speaker outlines the significant developments in particle physics, including the discovery of the muon, which revolutionized our understanding of fundamental particles. They discuss the contributions of various researchers, including Marietta Blau and Bibha Chowdhuri, who developed techniques for detecting high-energy particles. The speaker emphasizes the importance of these discoveries in shaping our current understanding of the universe and the standard model of particle physics.

The speaker describes the evolution of particle accelerators, from the initial experiments by Cockcroft and Walton to the development of the cyclotron by Ernest Lawrence. They highlight the growth of big science and the construction of large-scale laboratories, which led to the discovery of numerous particles and the establishment of the standard model. The speaker also discusses the practical applications of particle accelerators, such as cancer treatment, materials processing, and the invention of the worldwide web.

The speaker discusses the broader impact of particle physics on technology and society, including the development of superconducting magnets for MRI scanners and the potential for fusion reactors. They emphasize the importance of collaboration and the commercialization of technology that emerged from projects like the Tevatron. The speaker also highlights the invention of the worldwide web by Tim Berners-Lee at CERN, showcasing the far-reaching consequences of fundamental research.

In conclusion, the speaker reflects on the importance of collaboration, curiosity, and the freedom to persist in scientific discovery. They highlight the need for diverse perspectives and interdisciplinary work to tackle complex problems. The speaker also stresses the importance of creating environments where all people can thrive, as a key to unlocking future discoveries that will change our world in unimaginable ways.