From black holes to quantum computing - with Marika Taylor

The speaker opens the talk by thanking the audience for attending on a hot day and humorously referencing a fire on the first slide, hoping no one got 'burnt' on their journey. The main topics for the evening are introduced: black holes and quantum computers, two seemingly unrelated subjects that share surprising connections. The speaker hints at the intriguing relationship between these astrophysical phenomena and future technologies, such as the unhackable Quantum Internet. The talk promises to explore these connections, starting with the basics of black holes, which are well-known in popular culture through science fiction, and quantum computers, which operate on quantum states rather than traditional binary bits. The goal is to delve into the unexpected links between these areas, which have been a driving force in theoretical physics for decades.

This paragraph delves into the definition and characteristics of black holes, which are regions in space so dense that not even light can escape their gravitational pull. The concept dates back to the 18th century but gained prominence with Einstein's theory of relativity, which introduced the idea that gravity is a curvature of spacetime caused by mass. Black holes were initially considered mathematical curiosities, but the 1930s saw the first theoretical work suggesting that dying stars could collapse into black holes. The speaker also touches on the historical context of physics research, noting a shift in focus during World War II and a resurgence of black hole studies in the 1950s and 60s. The first identified astrophysical black hole, Cygnus X1, is mentioned as a milestone in the field.

The speaker explains the concept of the event horizon, the boundary surrounding a black hole from which nothing can escape. Detection of black holes is challenging due to their lack of emitted light. However, their gravitational influence on nearby stars and matter provides a way to identify them. By observing the motion of stars and the effects of gravitational lensing, astronomers can infer the presence of a black hole. The speaker also discusses the difficulty in detecting black holes and how their existence was confirmed through indirect observations, such as the motion of stars around an invisible center of gravity.

This paragraph discusses the advancements in astronomical observation that have allowed for higher resolution images of the night sky. The speaker mentions the use of arrays of telescopes on Earth and those in space to capture clearer images. The Event Horizon Telescope project is highlighted as a significant effort to capture high-resolution images of supermassive black holes. The iconic image of the supermassive black hole in M87 is shared as an example of such achievements, showing the event horizon and the surrounding accretion disc. The speaker also explains how the rotation of the black hole affects the appearance of the accretion disc from different viewing angles.

The speaker explores the portrayal of black holes in popular culture, specifically in the film 'Interstellar,' and how it relates to scientific understanding. The iconic image of the black hole in the movie, with its halo and accretion disc, is based on physics calculations by Kip Thorne's group. The visualization of the black hole in the film is discussed, including the gravitational lensing effect that causes light behind the black hole to form a halo. The speaker emphasizes that while the movie's depiction is based on theoretical calculations, actual black holes may emit light primarily in non-visible wavelengths.

The speaker introduces gravitational waves as a new method for detecting black holes, a concept predicted by Einstein's theory of general relativity. Gravitational waves are ripples in spacetime caused by the acceleration of massive objects, such as merging black holes. The speaker describes the process of detecting these waves using laser interferometers, which measure the minute changes in length caused by passing gravitational waves. The first detection of gravitational waves by the LIGO collaboration in 2015 is highlighted, marking a significant milestone in the study of black holes and other cosmic events.

This paragraph delves into the theoretical physics of black holes, particularly the concept of singularities at their core, where spacetime curvature becomes infinite. The speaker discusses the work of Hawking and Penrose, who contributed significantly to our understanding of black holes and were awarded the Nobel Prize for their work. The idea that black holes lead to singularities suggests that Einstein's theory of gravity is incomplete, hinting at a need for a quantum theory of gravity to fully understand these phenomena.

The speaker discusses the implications of the information loss paradox in black holes and its potential to lead to a paradigm shift in physics. The paradox arises from the fact that black holes seem to violate the rules of quantum mechanics by losing information. This has led to extensive research and thought experiments, with the hope that understanding black holes could reveal new physics. The speaker suggests that the resolution to this paradox may involve a more nuanced understanding of determinism and information storage in black holes.

The speaker explores the concept of quantum entanglement in the context of black holes, suggesting that the information about what falls into a black hole may be stored in a 'giant hard drive' at the event horizon. This idea connects black hole research with quantum computing, as the event horizon can be thought of as a highly efficient quantum memory. The speaker also discusses the 'fuzzball' and 'island' proposals, which offer different perspectives on how information is stored and retrieved as a black hole evaporates.

This paragraph draws a direct connection between black holes and quantum computing. The speaker explains how black holes can be seen as vast quantum information storage systems, with each unit of area on the event horizon capable of storing a quantum bit. The concept of quantum bits, or qubits, and their probabilistic nature is introduced, along with the idea of quantum entanglement. The speaker suggests that black holes could serve as thought experiments to understand the behavior of quantum computers, particularly in terms of information storage and error correction.

The speaker discusses the ongoing theoretical work at the intersection of black hole physics and quantum computing. This includes using black holes as models for understanding quantum error correction and the behavior of quantum information on a large scale. The speaker also touches on the practical challenges of building quantum computers and how insights from black hole research can inform the development of these technologies.

In conclusion, the speaker summarizes the journey from black holes to quantum computing, highlighting the contributions of astronomy experiments in understanding black hole event horizons and their implications for quantum information processing. The speaker emphasizes the importance of continued research in both fields, suggesting that advancements in our understanding of black holes can inform and improve quantum computing technologies.