Fay Dowker is Professor of Theoretical Physics at Imperial College London, where she works broadly on quantum gravity, and more particularly on an approach called causal set theory that takes the most basic pieces of the universe to be atoms of spacetime. In this episode, Robinson and Fay begin by discussing her studies with Stephen Hawking and their work on wormholes before turning to quantum gravity and causal set theory. Fay is also a faculty member at the John Bell Institute for the Foundations of Physics. If you’re interested in the foundations of physics—which you absolutely should be—then please check out the JBI, which is devoted to providing a home for research and education in this important area. Any donations are immensely helpful at this early stage in the institute’s life.
The John Bell Institute: https://www.johnbellinstitute.org
OUTLINE
00:00 In This Episode…
00:50 Introduction
04:49 How Do Physicists Think of Wormholes?
15:56 Stephen Hawking, Philosophy, and Quantum Gravity
26:00 Causal Set Theory and The Problem of Quantum Gravity
43:45 What is the Path Integral?
54:43 Is Spacetime Discrete?
57:40 Causal Set Theory and Black Holes
01:14:27 Lorentz Symmetry, Non-Locality, and Phenomenology in Causal Set Theory
Robinson’s Website: http://robinsonerhardt.com
Robinson Erhardt researches symbolic logic and the foundations of mathematics at Stanford University. Join him in conversations with philosophers, scientists, weightlifters, artists, and everyone in-between.
[…]
Fay Dowker speaks at a Perimeter Institute Public Lecture on November 2, 2011.
Black holes are hot! This discovery made by Stephen Hawking ties together gravity, spacetime, quantum matter, and thermal systems into the beautiful and exciting science of “Black Hole Thermodynamics”. Its beauty lies in the powerful way it speaks of the unity of physics. The excitement arises because it tells us that there is something lacking in our understanding of spacetime and, at the same time, gives us a major clue as to what the missing ingredient should be. Theoretical physicists at Perimeter Institute and elsewhere are pioneering a proposal, known as Causal Set Theory, for the structure held by these most fundamental atoms of spacetime. In this talk, Professor Dowker describes black hole thermodynamics and argue that it is telling us that spacetime itself is granular or “atomic” at very tiny scales.[…]
APRIL 21, 2024 JACKIE ANDRES
“The Magic Number.” All images © Tony Van Le
Although fleeting, Tony Van Le’s photos are a reminder of the wonder that comes from being deeply sensitive toward life’s mundane charm.
As John Koening writes in The Dictionary of Obscure Sorrows, the term sonder refers to “the realization that each random passerby is living a life as vivid and complex as your own—an epic story that continues invisibly around you.” This profound feeling reveals itself in Tony Van Le’s street photography, circling around the meaningful coincidences that he captures instantaneously.
“Into the Unknown”
Le is fueled by serendipity and strangeness. Having originally explored these grounds through music production, the artist has since moved toward manifesting a similar ethos through photography. Impassioned by the transient work of Vivian Maier, Le has spent years cultivating this calling, becoming more confident with focusing his lens on strangers over time. Purely candid and wondrously ephemeral, the artist approaches each street scene with a clear mind.
He explains, “When I’m out on the street, my mindset combines looking for the out-of-the-ordinary with trying to be a blank slate. By being fully attuned to the moment, I’m more open to the photographic potential of what I encounter.” Although fleeting, each snapshot is a reminder of the wonder that comes from being fully present and deeply sensitive toward life’s mundane charm. […]
“Nature’s Crown”
More: Street Photographer Tony Van Le Captures Beauty in Brevity — Colossal
A group of Native American soldiers devise a secret code for the Allies.
A group of Native American soldiers use their language to devise a secret code for the Allies. Can the Navajo code help win one of the fiercest battles of the war?
Helena Bonham Carter shines a light on extraordinary stories from World War Two. Join her for incredible tales of deception, acts of resistance and courage.
A BBC Studios Audio production for BBC Radio 4 and BBC Sounds.
Producer: Suniti Somaiya
Edit Producer: Melvin Rickarby
Assistant Producer: Lorna Reader
Executive Producer: Paul Smith
Written by Alex von Tunzelmann
Commissioning editor for Radio 4: Rhian Roberts
Source: BBC Radio 4 – History’s Secret Heroes, 14. The Unbreakable Navajo Code
