All posts by nickhggtt

Talk this week: Chris Smeenk

Please join us online at 10am (Eastern) on 3/3/21 for “Decoupling from the Initial State?” by Chris Smeenk (Western): details and registration at

Abstract: According to inflationary cosmology, the universe passed through a transient phase of exponential expansion that leaves several characteristic imprints in the universe’s post-inflationary state. This paradigm has enjoyed considerable phenomenological success, as a wide range of inflationary models are compatible with observations. The extent to which this success lends credibility to inflation has been a subject of ongoing debate. Here I will focus on whether the predictions of inflation are robust to changes in high-energy physics, or to features of the pre-inflationary initial state. The prospect of describing the early universe successfully without resolving the mysteries of quantum gravity has always been one of inflation’s appealing features. I will review arguments that inflation does not decouple from high energy physics in the same sense as other effective field theories in physics. Establishing how inflation can be implemented in a theory of quantum gravity is an ongoing challenge, and doing so is needed to address several long-standing foundational questions.

2021 Summer Institute

Morzine, France 27 June – 2 July 2021: International Summer Institute in the PHILOSOPHY OF COSMOLOGY and the PHILOSOPHY OF QUANTUM GRAVITY

In recent years, the philosophy of quantum gravity and the philosophy of cosmology have emerged as new fields in their own right, with several summer schools dedicated to each. However, they remain largely unconnected, even though their intersection promises new scientific insights of great significance to philosophical question and the advancement of physics. This Summer Institute proposes to address conceptual, metaphysical, and epistemological implications of big bang, black hole, and multiverse models in quantum gravity: the fundamental nature of space and time, especially the beginning of spacetime, ‘before’ time or ‘outside’ space; the multiverse; the nature of physical law; and how we might have knowledge of such things. These are just some of the questions that we will discuss in this Summer Institute, which addresses graduate students and postdocs from philosophy of physics and related fields. Application details

Faculty: Karen Crowther (Oslo), Nick Huggett (Illinois at Chicago), Mairi Sakellariadou (King’s College London), Chris Smeenk (Western), Francesca Vidotto (Western), David Wallace (Pittsburgh), Christian Wüthrich (Geneva).

This week’s speaker – Lee Smolin

Please join us (online) on Wednesday February 24th, for a talk by Lee Smolin, titled “Temporal naturalism”. The abstract is below, we start at 10am ET, and full details including registration are at

Abstract: I discuss the progress of a research program called temporal naturalism, whose aim is to reframe naturalism and relationalism based on the hypotheses that time is fundamental, while space is emergent.   By the fundamentality of time we mean that all that is real are causal processes that continually make definite facts out of previously  indefinites possibilities, thereby producing novel events out of predecessor events.   
Good beables to construct such a theory from are the views of events, which describe what properties an event was endowed with from its predecessor events, such as energy and momentum.  Thus there is a single universe made up of partial views of itself.

In a relational setting and with no distance, coordinates, fields, trajectories to draw from, the dynamics must be formulated in terms of views, and in particular in terms of differences amongst views.   The change between the view of an event and its immediate predecessors provides a notion of kinetic energy while potential energy is related to the variety, which is the total diversity of present causally unrelated views.  This is enough to derive a version of many body quantum theory; which lives in a space that we show emerges from the solutions of the theory. Thus the program shows promise of reconciling both the problems of quantum foundations and quantum gravity, within a single completion.   

The part of the program just described has been developed under the names of energetic causal sets and the causal theory of views.  Another key aspect is the view that the laws of physics cannot be fixed, but must evolve, in a way as to explain howthe choices the universe has made of the fundamental forces and particles have come about through an evolutionary, dynamical process.   If there is time I will discuss three realizations of this idea: cosmological natural selection, the principle of precedence and the hypothesis that the vacua of quantum fields can learn to navigate a landscape of possible laws, usingthe same mechanisms that allow a deep neural network to learn.

This work has appeared in six books and a number of papers; key collaborators have included Julian Barbour,Fotini Markopoulou, Stuart Kauffman, Joao Magueijo, Stephon Alexander, Roberto Mangabeira Unger, Jaron Lanier, Marina Cortes, Andrew Liddle and Clelia Verde.

Talk this week: Vidotto

Please join us (virtually) on Feb 17, at 10:15ET for Francesca Vidotto, speaking on “Quantum Gravity in Practice”. Full details and registration at

Abstract: I present a recent concrete calculation in Spinfoam Cosmology -the application of the covariant LQG techniques to the cosmos- as an example to discuss a number of conceptual issues that are at the core of quantum gravity and cosmology. These include: What are the observables when localization does not rely on background space and time? What are the degrees of freedom? What is the role of quantum fluctuations of spacetime? What’s the interplay between the Planck scale and the cosmological scale? How should we think about time in this picture?

Talk this week: Wüthrich

On Wednesday February 10th, our very own Christian Wüthrich will present  “Laws Beyond Spacetime”, as part of our online seminar series at the Pittsburgh Center for Philosophy of Science. Please join us. Full details and registration at

Abstract: Quantum gravity’s suggestion that spacetime may be emergent and so only exist contingently would force a radical reconception of extant analyses of laws of nature. Humeanism presupposes a spatiotemporal mosaic of particular matters of fact on which laws supervene. I will show how the Humean supervenience basis of non-modal facts can be reconceived, avoiding a reliance on fundamental spacetime. However, it is unclear that naturalistic forms of Humeanism can maintain their commitment to there being no necessary connections among distinct entities. This talk is based on a joint project with Vincent Lam.

Talk this week

The first talk of our seminar series – by Nick Huggett – is on Wednesday February 3rd, at 9.15 CST.

Laws for Nowhere: the standard concept of law is, I suggest, significantly spatiotemporal, posing the question of how there can be laws in non-spatiotemporal theories, and most pointedly how laws could hold in non-spatiotemporal regions of spacetime. I describe a couple of quantum gravity models of the Big Bang (in string theory and group field theory), in a provisional attempt to demonstrate how such questions might arise.

Please come via zoom, or watch on Facebook. Details at

Speaker series

UPDATE: Participants please register here:

We are happy to announce an online seminar series that we are running in conjunction with the Center for Philosophy of Science at the University of Pittsburgh, featuring talks by Francesca Vidotto, Lee Smolin, Chris Smeenk, Fay Dowker, on the intersection of quantum gravity and cosmology. The first lecture is on February 3rd. Full details are here:

Please join us via zoom!

Talk – Mike Schneider

We are pleased to announce a talk by Mike D. Schneider (Pittsburgh), Trans-Planckian Philosophy of Cosmology, on November 25, 2020, at 11.15am Chicago time (5.15 UTC), via zoom. Find full details at Hope to see you there!

Or follow our YouTube livestream: