BSPS Video Lecture: Parallel Universes

Is Schrödinger’s cat alive or dead? This thought experiment was devised to illustrate a fundamental puzzle in quantum mechanics. A radical solution is that the cat is both alive and dead, but in different, parallel universes. This is the ‘many-worlds interpretation’ of quantum mechanics and our panel of philosophers and physicists will discuss why it is controversial and its strange consequences.

This panel lecture features Fay Dowker (Professor of Theoretical Physics, Imperial College London), Eleanor Knox (Senior Lecturer in Philosophy, King’s College London), and Simon Saunders (Professor of Philosophy of Physics, University of Oxford). It is chaired by Jonathan Birch, a Fellow in the The Forum and Assistant Professor of Philosophy, Logic and Scientific Method at LSE.

The event was held in collaboration with Forum for European Philosophy. For more details or to download a podcast, visit the event webpage.

BSPS Video Lecture: Heather Dyke (LSE), “Experience of Passage in a Static World”

Abstract: The view that experience seems to tell us directly that time flows has long been accepted by both A-theorists and B-theorists in the philosophy of time. A-theorists take it as a powerful endorsement of their position, sometimes using it explicitly in an argument for their view, and other times more implicitly, as a kind of non-negotiable, experiential given. B-theorists have tended to accept that we have this experience, and have sought alternative explanations for it, consistent with the B-theory. The so-called argument from temporal experience has received a lot of attention in recent years, and B-theory responses to it have begun to coalesce around two distinct positions. Illusionists adopt the traditional B-theoretic response of accepting that we do seem to experience temporal passage, and offering a B-theoretic explanation of it, thereby arguing that the experience is illusory. Veridicalists, on the face of it, take a more radical stance. They deny that we seem to experience temporal passage at all. I argue that there is something right in each of these responses, and by combining these features, we may be able to forge a third alternative, namely, that our temporal phenomenology is exactly what we should expect if the B-theory is true, and given our physical and psychological makeup. I discuss some results from psychology and cognitive science to support my view. In particular, I develop an explanation for the phenomenon that we sometimes seem to experience time speeding up or slowing down, a feature of temporal experience which has been largely neglected in the philosophical literature.

BSPS Video Lecture: Karim Thébault (Bristol), “Cosmic Singularity Resolution via Quantum Evolution”

Classical models of the universe generically feature a big bang singularity. That is, when we consider progressively earlier and earlier times, physical quantities stop behaving in a reasonable way. A particular problem is that physical quantities related to the curvature of spacetime become divergent. A long standing hope is that a theory of quantum gravity would “resolve” the big bang singularity by providing quantum models of the early universe in which all physical quantities are always finite. Unfortunately, not only does the conventional Wheeler-DeWitt approach to quantum gravity fail to resolve the big bang singularity in this sense (without the addition of loop variables or exotic matter), but it also renders the universe fundamentally timeless. We offer a new proposal for singularity resolution in quantum cosmology based upon quantum evolution. In particular, we advocate a new approach to quantum cosmology based upon a Schrödinger equation for the universe. For simple models with a massless scalar field and positive cosmological constant we show that: i) well-behaved quantum observables can be constructed; ii) generic solutions to the universal Schrödinger equation are singularity-free; and iii) specific solutions display novel phenomenology including a cosmic bounce.