This book offers a clear account of timelessness together with the discussion of temporality in fundamental physics and cosmology. The multi-disciplinary approach to the problem of time and timelessness shows the remarkable difference between pre-relativistic debates and current developments. This book thoroughly discusses notions of timelessness and time emerging in the most recent literature on Quantum Gravity, String Theory and Cosmology. The contributions explore, among many aspects, the historical-philosophical roots of the notions of temporality and atemporality, the role of mathematics in defining time and temporality with respect to both order relations and causality, approaches to quantum gravity and cosmology that make use of quantum fluids and condensate to approximate space–time in general relativity, time and timelessness in black holes and the problem of cosmological time in bouncing cosmologies. The novelty of this volume lies in the interaction among scientists, philosophers, and historians in exploring the nature of time and timelessness and the origin of these concepts. The book represents a valuable toolkit for researchers and graduate students in physics, cosmology, philosophy and the history of those fields.

A professor of physics and astronomy studies a theory that time is reversible, and explains how physicists have generally been reluctant to accept the reversibility of time because of the implied causal paradoxes. Illustrations.

This invaluable book provides a broad and comprehensive introduction to the fascinating and beautiful subject of timeless approaches in physics, focusing the attention in particular on significant models developed recently by the author. It presents relevant and novel perspectives in 21st century theoretical physics as regards the arena of physical processes and its geometry (both in special relativity, quantum mechanics, the quantum gravity domain and about the quantum vacuum). The timeless approach may be used as a source of reference by researchers in theoretical physics and at the same time it is also suitable for graduate students in physics who wish to have an extend view of some of the classic and fundamental models in the subject.

Provides basic evidence for the nonexistence of time, explaining what a timeless universe is like and showing how the nonexistence of time solves a great paradox of modern science.

The book is based on the author's PhD thesis, which deals with the concept of time in quantum gravity and its relevance for the physics of the early Universe. It presents a consistent and complete new relational formulation of quantum gravity (more specifically, of quantum mechanics models with diffeomorphism invariance), which is applied to potentially observable cosmological effects. The work provides answers to the following questions: How can the dynamics of quantum states of matter and geometry be defined in a diffeomorphism-invariant way? What is the relevant space of physical states and which operators act on it? How are the quantum states related to probabilities in the absence of a preferred time? The answers can provide a further part of the route to constructing a fundamental theory of quantum gravity. The book is well-suited to graduate students as well as professional researchers in the fields of general relativity and gravitation, cosmology, and quantum foundations.

The concept of time has fascinated humanity throughout recorded history, and it remains one of the biggest mysteries in science and philosophy. Time is clearly one of the fundamental building blocks of the universe and thus a deeper understanding of nature at a fundamental level also demands a comprehension of time. Furthermore, the origins of the universe are closely intertwined with the puzzle of time: Did time emerge at the Big Bang? Why does the arrow of time ‘conspire’ with the order of the initial state of the universe? This book addresses many of the most important questions about time: What is time, and is it fundamental or emergent? Why is there such an arrow of time, closely related to the initial state of the universe, and why do the cosmic, thermodynamic and other arrows agree? These issues are discussed here by leading experts, and each offers a new perspective on the debate. Their contributions delve into the most difficult research topic in physics, also describing the latest cutting edge research on the subject. The book also offers readers a comparison between the different outlooks of philosophy, physics and cosmology on the puzzle of time. This volume is intended to be useful for research purposes, but most chapters are also accessible to a more general audience of scientifically educated readers looking for deeper insights.