We invite interested scholars for short visits to the Cosmology Beyond Spacetime research group located in the philosophy department at the University of Illinois at Chicago in Spring 2022. To facilitate visits we can offer financial assistance for travel and lodging, office facilities, and of course excellent intellectual company. Visits can be from a few days to a few weeks (or possibly longer).
We hope to have range of visitors: faculty and graduate students; general philosophers, philosophers of physics, and physicists; those sharing their expertise, and those learning about the philosophy of quantum gravity and the work of our group and speakers. Visitors will help us inform the philosophical and physics communities about philosophical issues in quantum gravity; and they will help us learn more about these philosophical dimensions though our interactions. While visitors will be credentialed philosophers or physicists, in some cases a credible interest in professional engagement with the group will be more important than prior work in quantum gravity.
In the first instance, potential visitors are requested to send a brief (one page) letter of interest, explaining their current academic status, research focus, and interest in our project. Please also explain any special activities you would like to undertake with the group, date(s) you would like to visit, and estimated cost of a flight. We will request further information as needed, and discuss times and budgets (up to $500, with the possibility of more for longer visits, depending on demand) with successful applicants.
We especially encourage applications from women and underrepresented minorities.
With sadness we note the passing of Steven Weinberg. His influence on physics has of course been enormous, but – despite his public antipathy to ‘philosophy’ – his conceptual insights into quantum field theory and gravity (and more) have also greatly influenced many of us in philosophy of physics. Notably for me, his work on the renormalization group, the relation between fields and particle in QFT, and – especially relevant to this website – his contributions to our understanding of the scope and limits of gravity as a QFT. Beyond that of course are his amazing popular works in physics, that I expect helped bring many of us to physics in the first place.
Blog followers may be interested in the following interview of Tushar Menon by David Baker, on “Taking up Superspace”, a paper published in the project collection “Philosophy Beyond Spacetime” (OUP, 2021). https://www.youtube.com/watch?v=4Mj_3FZWMIM
We are delighted to announce that Mike Schneider (currently a postdoc at Pittsburgh) will be joining our group at UIC as a postdoctoral research fellow for 2021-22. If you don’t yet know Mike, you can read about his work on his website.
Wednesday, 14 April 2021 at 9:30am Chicago Time– Craig Callender (UCSD) and Eugene Chua (UCSD): No Time for Time from No-Time
Programs in quantum gravity often claim that time emerges from fundamentally timeless physics. In the semiclassical time program time arises only after approximations are taken. Here we ask what justifies taking these approximations and show that time seems to sneak in when answering this question. This raises the worry that the approach is either unjustified or circular in deriving time from no–time.
ABSTRACT: A non-commutative field theory (for scalar fields in this talk) introduces a fundamental area, as the measure of non-commutation (analogous to Planck’s constant), but does it signify a minimum area? Drawing on work with Fedele Lizzi (Napoli) and Tushar Menon (Cambridge) I will explain a sense in which this is correct, implying that points are ‘missing’. This situation raises several questions: how should the theory then be understood? Can its algebraic formulation be interpreted as describing the basic degrees of freedom of a world? And if so, how do we understand the ‘emergence’ of continuous, classical spacetime physics?
Abstract: Could the universe have had no beginning? I don’t mean, in raising thisquestion, to deny or throw doubt on Big Bang cosmology and the existence in the past of a hot, dense state of Planckian curvatureand temperature. But, in that case, how is the question to be interpreted given that—if we accept the standard cosmology— the Lorentzian manifold structure of spacetime breaks down at the Big Bang? Certainly, the *continuum* concept of timein our cosmological epoch “begins” at the Big Bang. Can we even ask what happened “before” that? The causal set approach to the problem of quantum gravity provides an arena in which to address the question of origins, in which it makes sense to ask what happened before the Big Bang and in which a clear distinction can be made between models of the universe which are “past infinite” and “past finite”. I will describe work with Stav Zalel and Bruno Bento in which we construct a framework for dynamics for causal sets which can result in past infinite universes.
Title: Missing the point in (noncommutative) field theory.
Abstract: A non-commutative field theory (for scalar fields in this talk) introduces a fundamental area, as the measure of non-commutation (analogous to Planck’s constant), but does it signify a minimum area? Drawing on work with Fedele Lizzi (Napoli) and Tushar Menon (Cambridge) I will explain a sense in which this is correct, implying that points are ‘missing’. This situation raises several questions: how should the theory then be understood? Can its algebraic formulation be interpreted as describing the basic degrees of freedom of a world? And if so, how do we understand the ‘emergence’ of continuous, classical spacetime physics?
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.