Cast IT

Cast IT is a popular science podcast about foundations of information technology, hosted at IT University of Copenhagen.

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Felienne Hermans: The Programmer’s Brain and Hedy

Duration: 01:07:18

Description: Felienne Hermans is full professor of Computer Science Education at the Vrije Universiteit Amsterdam.

Felienne is the author of the 2021 book The Programmer's Brain, a very readable and highly insightful introduction to the cognitive science behind how human brains learn programming. Why is programming hard to learn, and what can we do about that, both as learners and teachers? We recommended this for everyone, but it is particularly useful for those who just started to learn programming, as well as people who try to teach others. 

Felienne’s most recent project is Hedy, a programming language aimed at beginners – including children – and that realises many of the insights from The programmer’s brain about why programming is hard to learn. Hedy is a “real” programming language in that it is unapologetically text-based, but the language design is gradual, progressing from an extremely lenient but incomplete language to a nontrivial subset of Python. 

The language is under active development and constantly exposed to feedback from children who actually learn programming. We find this brilliant and are particularly impressed by the possibility of Hedy to teach some programming to everyone, rather than all programming to some people.

Nutan Limaye: Computational complexity

Duration: 01:03:44

Description: Nutan Limaye is an associate professor at IT University of Copenhagen and an internationally leading researcher in computational complexity.

Nutan’s research focus is on the most prestigious and fundamental questions in computer science, namely: which problems can be solved with limited computational resources? Her recent breakthrough result, with Srinivasan and Tavenas, received the best paper award at the Foundations of Computer Science conference in 2021 and shows that algebraic circuits of constant size require superpolynomial depth.

We ask Nutan what these words even mean, and take a deep dive into the foundations of computer science. What are computational problems, computational models, algorithms, and how does one reason scientifically about such broad concepts? In particular, how does an impossibility result even make sense: how can one prove that a problem can never be solved, no matter how many clever ideas we (or anybody else) may have in the future?

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Mikkel Thorup: Digital Contact Tracing

Duration: 01:06:54

Description: Mikkel Thorup is professor of Computer Science at Copenhagen University and an internationally leading researcher in the theory of algorithms. During the Covid-19 pandemic, he has served on the scientific board advising the Danish authorities on the development of a national contact tracing app using mobile phones for exposure notification.

We sit down with Mikkel, exposure notification apps dutifully switched on, and talk about how such an application works. The Danish system, “SmitteStop”, uses Digital Privacy-Preserving Proximity Tracing. What does that even mean – how is the protocol defined, what is the mechanism by which privacy is preserved (and to which extent), and which role does the Google–Apple API play in the application?

Apart from the technical issues, we probe several issues on the fault line of technology and society. What are the alternatives to privacy-preserving exposure notification? E.g., could we do much more, and – to the extent that our phones already track everything and we share it freely – why aren’t we just using that information during a pandemic? What are the trade-offs between safety and liberty, is privacy a form of manslaughter, whom should we trust with our data, and how do different cultures around the globe manifest in deciding these tradeoffs?

Robin Hanson: The Age of Mind Uploading

Duration: 02:10:24

Description: Robin Hanson is an associate professor of economics at George Mason University and a research associate at the Future of Humanity Institute of Oxford University and one the world’s most influential futurists. 

We talk to Robin about how rigorous social science can help us describe a society in which “mind uploading” – the idea of simulating whole brains on digital hardware – might actually look. How does a society look where most minds live their lives in virtual reality, immortals in a world where labour is plentiful? Will the emulated humans be rich or poor, happy or miserable, care-free or stressed, honest or false, lazy or industrious, diverse or all the same? Will they fall in love, have friends, swear, distrust others, commit suicide, and find meaning in their lives?

Robin’s book about this topic is “The Age of Em: Work, Love and Life when Robots Rule the Earth” (Oxford University Press, 2016). Robin blogs about rationality at

Tim Roughgarden: The Price of Anarchy

Duration: 01:21:57

Description: Tim Roughgarden is professor in the Computer Science and Management Science and Engineering Departments at Stanford University. He is also a very active science communicator, hosting a popular algorithms course on the Coursera online learning platform. 

Among many recognitions, Tim has received the Gödel Prize for his research in computational game theory, a field that resides in the intersection of two disciplines: economics and computer science. We talk to Tim about one of the central insights of that work: the Prize of Anarchy, which quantifies the loss in efficiency of a system due to selfish behaviour of its agents.

We also look at applications of game-theoretic algorithms in the real world, when Tim explains the role that computer science played in designing the 2016 “incentive auction” used to by the US Federal Communications Commission (FCC) to buy and sell broadcast airwaves. 

Claire Mathieu: College Admission Algorithms in the Real World

Duration: 47:48

Description: Claire Mathieu is a leading researcher in algorithms design and director of research at Centre national de la recherche scientifique (CNRS) in Paris, France.) Claire has been involved in the 2018 redesign of the college admission procedure in France, where close to a million students apply for more than ten thousand different college programmes. At the root of the procedure is the famous and widely used Stable Marriage method of Gale and Shapley (1962), a result that was recognised with the 2012 Nobel Prize in Economics.

Claire explains to us the basic algorithmic ideas, but also the many challenging details that must be addressed when an otherwise clean and well-understood procedure is implemented to tackle a real-world scenario. Many domain-specific peculiarities arise, such as social, cultural, political, administrative, and legal issues, which are themselves often ill-defined and frequently conflicting.

The episode was recorded on 20 August 2018, during the European Symposium of Algorithms 2018, hosted by Aalto University in Helsinki, Finland.

Yves Bertot: Verifying One Million Digits of Pi

Duration: 01:07:38

Description: Yves Bertot is a senior researcher that the French Institute for Research in Computer Science and Automation (INRIA) in Sophia Antipolis and a leading researcher on correctness of software and the verification of mathematical proofs. Recently, his team was able to formally verify the correctness of the computation on the one millionth decimal digit of pi (which is 1, by the way), including a formally verifiable proof of the mathematics behind the formula and the correctness of the implementation of arithmetic operations used in the computation. We use this result as an inspiration to talk about interactive theorem proving and improving software quality.

Yves’ book with Pierre Casterán about interactive theorem proving using the Coq system is “Interactive Theorem Proving and Program Development – Coq'Art: The Calculus of Inductive Constructions”, Springer Verlag, EATCS Texts in Theoretical Computer Science, 2004, ISBN 3-540-20854-2.

Sarah Pink: Digital Ethnography

Duration: 47:00

Description: Sarah Pink is a Professor of Design and Media Ethnography at RMIT University, Australia, and the author or co-editor of several books about digital ethnography.
To approach this area, we get Sarah’s help with some conceptual groundwork about the methods, values, and history of ethnography, and its relation to neighbouring fields such as anthropology or cultural geography. But the conversation focusses on digital ethnography: Information technology changes not only the methods of ethnography by providing tools or modes of expression, but also raises new questions by changing notions of embodiment, geographic place, and social relation, all of which are central themes for ethnographers. We also talk about how an field that largely eschews prediction and hypothesis can reason about future technology such as self-driving cars.

Sarah’s book is Pink et al., Digital Ethnography: Principles and Practice, SAGE Publications, 2016.

Roman Beck: Blockchain

Duration: 01:05:56

Description: Roman Beck is professor of Business Informatics at IT University of Copenhagen and the head of the European Blockchain Center. We talk to Roman about blockchain, a cryptographically secure, distributed database technology sometimes called a “trust machine.” Blockchain applications include the cryptocurrency Bitcoin, as well as various ideas for ensuring trust across institutional boundaries, such as contracts. It may also serve as the conceptual infrastructure of the next generation Internet. Which are the main ideas underlying this technology, how does it makes us think differently about digital information, and what are the possibilities, challenges, promises, and threats of this technology?

Ivan Damgård: Secure Multi-Party Computation

Duration: 01:01:23

Description: Ivan Bjerre Damgård is professor of theoretical computer science at Aarhus University, Denmark, and one of the world’s leading researchers in the foundations of cryptography. Among other things, Ivan is known for the Merkle–Damgård construction, which underlies many modern digital signatures. We talk to Ivan about the mathematical basics of modern cryptography, internet security, authentication, secret sharing, and privacy. This includes the emerging field of secure multiparty computation: how can individuals collaborate to compute a solution without revealing too much of their private information?
Ivan’s recent book on these matters is Ronald Cramer, Ivan Bjerre Damgård, and Jesper Buus Nielsen, “Secure Multiparty Computation and Secret Sharing,” Cambridge University Press, 2015.

Carsten Schürmann: Electronic Elections

Duration: 01:15:14

Description: Carsten Schürmann is the leader of the Demtech research center, which studies the interplay between technology and democracy. Carsten is a world leading expert in computer security and critical digital infrastructure, with a background in the theory of programming languages and logics.

We talk to him about digital democracy, in particular electronic elections, including online voting. The goal of democratic elections is the peaceful transition of government, which means that both winners and loser must trust the outcome of the result. How is this trust generated if the details of voting are no longer transparent?

Recorded on 21 April 2017.

Espen Aarseth: Game Studies from The Hobbit to Minecraft

Duration: 01:06:30

Description: Espen Aarseth, professor in Game Studies, is the Head of the Center of Computer Games Research at IT University of Copenhagen and the founding editor-in-chief of the journal Game Studies. We talk to Espen about founding computer games research as an academic discipline, the Games study programme at ITU, what a game is (entertainment? sports? waste of time? cultural artefact? social activity? storytelling? shared illusion?), PewDiePie, how the established narratological concepts of literary theory succeed or fail in describing games, playing The Hobbit over a landline phone in the 1980s, and Dungeons & Dragons.

Recorded on 12 October 2017.

Rebecca Slayton: Cybersecurity and Star Wars

Duration: 53:56

Description: Rebecca Slayton is a professor at the Department of Science and Technology Studies and Judith Reppy Institute for Peace and Conflict Studies at Cornell University.
We talk to Rebecca about cybersecurity, the early history of software engineering during the Cold War, the role of scientific and technological expertise in public policy, and how to think about risk and reliability. Rebecca’s book on how knowledge about computing was shaped by and influenced the development of US missile defence during the Cold War is “Arguments that Count: Physics, Computing, and Missile Defense, 1949-2012” (MIT Press, 2013), which won the Computer History Museum Prize in 2015.

Recorded on 18 May 2017.

Olle Häggström: Technology and the Future of Humanity

Duration: 01:17:05

Description: Olle Häggström is a Professor of mathematical statistics at Chalmers University of Gothenburg, Sweden, and the member of the Royal Swedish Academy of Science. He is also a leading Swedish public intellectual and prolific debater in science, pseudoscience, technology, and education. We talk to Olle about the potential dangers associated with various emerging technologies—how do we start thinking about the catastrophic risks that may be associated with scientific advances that we have not completed?

Our focus at Cast IT are potential advances in Artificial Intelligence towards general “Superintelligence,” sometimes called the intelligence explosion, the technological Singularity, or the robot apocalypse. Olle’s 2016 book about these issues is called “Here Be Dragons: Science, Technology and the Future of Humanity,” published by Oxford University Press.

Recorded on 8 May 2017.

Vincent F. Hendricks: The truth in digital society

Duration: 55:21

Description: We ask Vincent F. Hendricks, professor of formal philosophy at Copenhagen University and the director of the Center for Information and Bubble Studies how to think about information, knowledge, and truth, in the internet age, where information is  quickly shared or algorithmically curated, and  where the model of liberal democracy, such as the public sphere, are undergoing rapid change. We talk about fake news, Trump, radical scepticism, social psychology, filter bubbles, power laws of attention economics, and pluralistic ignorance.

Vincent’s web page is at and his 2016 book on explaining individual behaviour on the social net is Hendricks and Hansen, “Infostorms,” Springer 2016.