Month: July 2024

An Invitation to Universality in Physics, Computer Science, and Beyond

Tomáš Gonda, Gemma De les Coves

A universal Turing machine is a powerful concept – a single device can compute any function that is computable. A universal spin model, similarly, is a class of physical systems whose low energy behavior simulates that of any spin system. Our categorical framework for universality (arXiv:2307.06851) captures these and other examples of universality as instances. In this article, we present an accessible account thereof with a focus on its basic ingredients and ways to use it. Specifically, we show how to identify necessary conditions for universality, compare types of universality within each instance, and establish that universality and negation give rise to unreachability (such as uncomputability).

Read the full article at: arxiv.org

Minimalist exploration strategies for robot swarms at the edge of chaos

Vinicius Sartorio, Luigi Feola, Emanuel Estrada, Vito Trianni, Jonata Tyska Carvalho

Effective exploration abilities are fundamental for robot swarms, especially when small, inexpensive robots are employed (e.g., micro- or nano-robots). Random walks are often the only viable choice if robots are too constrained regarding sensors and computation to implement state-of-the-art solutions. However, identifying the best random walk parameterisation may not be trivial. Additionally, variability among robots in terms of motion abilities-a very common condition when precise calibration is not possible-introduces the need for flexible solutions. This study explores how random walks that present chaotic or edge-of-chaos dynamics can be generated. We also evaluate their effectiveness for a simple exploration task performed by a swarm of simulated Kilobots. First, we show how Random Boolean Networks can be used as controllers for the Kilobots, achieving a significant performance improvement compared to the best parameterisation of a Lévy-modulated Correlated Random Walk. Second, we demonstrate how chaotic dynamics are beneficial to maximise exploration effectiveness. Finally, we demonstrate how the exploration behavior produced by Boolean Networks can be optimized through an Evolutionary Robotics approach while maintaining the chaotic dynamics of the networks.

Read the full article at: arxiv.org

Life as No One Knows It, by Sara Imari Walker

An intriguing new scientific theory that explains what life is and how it emerges.

What is life? This is among the most difficult open problems in science, right up there with the nature of consciousness and the existence of matter. All the definitions we have fall short. None help us understand how life originates or the full range of possibilities for what life on other planets might look like.

In Life as No One Knows It, physicist and astrobiologist Sara Imari Walker argues that solving the origin of life requires radical new thinking and an experimentally testable theory for what life is. This is an urgent issue for efforts to make life from scratch in laboratories here on Earth and missions searching for life on other planets.

Walker proposes a new paradigm for understanding what physics encompasses and what we recognize as life. She invites us into a world of maverick scientists working without a map, seeking not just answers but better ways to formulate the biggest questions we have about the universe. The book culminates with the bold proposal of a new theory for identifying and classifying life, one that applies not just to biological life on Earth but to any instance of life in the universe. Rigorous, accessible, and vital, Life as No One Knows It celebrates the mystery of life and the explanatory power of physics.

More at: www.penguinrandomhouse.com

How Is Science Even Possible?

How are scientists able to crack fundamental questions about nature and life? How does math make the complex cosmos understandable? In this episode, the physicist Nigel Goldenfeld and co-host Steven Strogatz explore the deep foundations of the scientific process.

Read the full article at: www.quantamagazine.org

Evolving reservoir computers reveals bidirectional coupling between predictive power and emergent dynamics

Hanna M. Tolle, Andrea I Luppi, Anil K. Seth, Pedro A. M. Mediano

Biological neural networks can perform complex computations to predict their environment, far above the limited predictive capabilities of individual neurons. While conventional approaches to understanding these computations often focus on isolating the contributions of single neurons, here we argue that a deeper understanding requires considering emergent dynamics – dynamics that make the whole system “more than the sum of its parts”. Specifically, we examine the relationship between prediction performance and emergence by leveraging recent quantitative metrics of emergence, derived from Partial Information Decomposition, and by modelling the prediction of environmental dynamics in a bio-inspired computational framework known as reservoir computing. Notably, we reveal a bidirectional coupling between prediction performance and emergence, which generalises across task environments and reservoir network topologies, and is recapitulated by three key results: 1) Optimising hyperparameters for performance enhances emergent dynamics, and vice versa; 2) Emergent dynamics represent a near sufficient criterion for prediction success in all task environments, and an almost necessary criterion in most environments; 3) Training reservoir computers on larger datasets results in stronger emergent dynamics, which contain task-relevant information crucial for performance. Overall, our study points to a pivotal role of emergence in facilitating environmental predictions in a bio-inspired computational architecture.

Read the full article at: arxiv.org