The Physics of Fine-Tuning

Simon Friederich, Natalja Deng, and Erik Curiel participate in a roundtable discussion addressing questions around probability, fine-tuning, and arguments for a multiverse or deity. Simon Friederich, Natalja Deng, and Erik Curiel participate in a roundtable discussion addressing questions around probability, fine-tuning, and arguments for a multiverse or deity. This discussion was conducted at the Lindeman Lecture Theatre, Clarendon Laboratory, Oxford, on October 6, 2016.

Erik Curiel explains the challenges in making assessments of probability by making assumptions about the space of universes--or cosmological models--that our theories allow. Erik Curiel (Munich Center for Mathematical Philosophy) explains the difficulty of making various concepts of and relating to probability precise, rigorous and physically significant when attempting to apply them in reasoning about objects (e.g., spacetimes) living in infinite-dimensional spaces, working through several examples from cosmology. He concludes that most standard forms of argument used in cosmology to estimate the likelihood of the occurrence of various properties or behaviors of spacetimes have serious mathematical, physical and conceptual problems. This lecture was conducted at the Lindeman Lecture Theatre, Clarendon Laboratory, Oxford, on October 6, 2016.

Natalja Deng discusses whether the apparent fine-tuning of the universe for life can be evidence for a divine creator. Natalja Deng (Yonsei University) comments on two responses to the fine-tuning argument for god, namely one based on dismissive priors , and one based on a ‘God-of-the-gaps’ style objection by theistic design theorists. She suggests that the latter response amounts to a practice-based constraint on theistic conceptions, and that often, theistic conceptions that meet this constraint are vulnerable to the former objection. This lecture was conducted at the Lindeman Lecture Theatre, Clarendon Laboratory, Oxford, on October 6, 2016.

Simon Friederich reviews the challenges that arise in using empirical evidence that the universe is tuned for life to evaluate multiverse hypothesis. Simon Friederich (University of Groningen) offers a panoramic view of intricacies and challenges that arise in the assessment of empirical evidence concerning multiverse theories and the relevance of fine-tuning for life. This lecture was conducted at the Lindeman Lecture Theatre, Clarendon Laboratory, Oxford, on October 6, 2016.

Erik Curiel and Simon Friederich hash out the problems we encounter when we look for evidence of a multiverse. How do we gain evidence for a multiverse? In the final part of their discussion, Erik Curiel and Simon Friederich hash out the problems we encounter when we try to use our observations as evidence for the multiverse. This discussion was conducted at the University of Oxford on October 6, 2017.

How similar is the fine-tuning of our universe to probabilistic reasoning we use and understand? Simon Friederich and Erik Curiel go through a series of examples. In the third part of their discussion, Simon Friederich and Erik Curiel go over the connection between a widely recognized fallacy--the Gambler’s Fallacy--and the fine-tuning argument. How similar is the fine-tuning argument for the multiverse to common ways of reasoning from observations to likelihoods? This discussion was conducted at the University of Oxford on October 6, 2017.

Erik Curiel and Simon Friederich discuss how reasoning in cosmology sometimes conflates topological stability with probability, and why that might be wrong. In the second part of their discussion, Erik Curiel and Simon Friederich talk about the connection between stability arguments, which are popular in discussions of fine-tuning, and probability. Erik raises a problem for a common form of reasoning in cosmology. This discussion was conducted at the University of Oxford on October 6, 2017.

Simon Friederich and Erik Curiel discuss the problems fine-tuning arguments raise for our understanding of probability. In the first part of their discussion, Simon Friederich and Erik Curiel outline the fine-tuning argument and discuss the problems it raises for our understanding of probability. This discussion was conducted at the University of Oxford on October 6, 2017.

In the fourth part of their discussion, Pedro Ferreira and Jerome Martin conjecture about the future of inflation. They talk about the potential for new evidence for and against the theory, and the variety of new probes into our cosmological environment. This discussion was conducted at the University of Oxford on March 15, 2017.

In the third part of their discussion, Pedro Ferreira and Jerome Martin talk about whether one should look for a deeper physical theory when one’s current theory is well-supported by observation. They discuss the rise of inflationary theory, its alternatives, and our expectations for future physics. This discussion was conducted at the University of Oxford on March 15, 2017.

In the second part of their discussion, Pedro Ferreira and Jerome Martin consider ways to build the naturalness of an inflationary model into our expectations for observing it. They debate the feasibility of measuring the degree to which an inflationary model is inspired by considerations from other parts of physics, and describe the applicability of Bayesian methods when we have background knowledge. This discussion was conducted at the University of Oxford on March 15, 2017.

In the first part of their discussion, Pedro Ferreira and Jerome Martin talk about the variety of inflationary models. They discuss methods for distinguishing between them based on evidence and describe the application of Bayesian statistics to inflation. This discussion was conducted at the University of Oxford on March 15, 2017.

What should we expect to learn in the future? In the fourth part of their chat, Dave Sloan and Robert Brandenberger talk about how we expect inflationary theory to develop, and how observations may lead to new physics in this area.

In the third part of their discussion, Dave Sloan and Robert Brandenberger explain the relationship between string theory and inflationary models. Can inflation arise from particle physics, or do we need to look for alternative models? This discussion was conducted at the University of Oxford on March 14, 2017.

In the second part of their discussion, Dave Sloan and Robert Brandenberger tell us what inflation predicts and whether inflation itself seems fine-tuned. This discussion was conducted at the University of Oxford on March 14, 2017.

In the first part of their discussion, Dave Sloan and Robert Brandenberger go over our evidence for inflationary theories and discuss how inflationary models improve on the hot big bang. This discussion was conducted at the University of Oxford on March 14, 2017.

Professor Joe Silk talks with Professor Robert Brandenberger, Professor Jerome Martin, and Dr. Dave Sloan about the current state of research and controversies surrounding inflation. They discuss the possibility of connecting inflation to string theory and the likelihood of the initial conditions required by inflationary models. This lecture was conducted at the Dennis Sciama Theatre at the Denys Wilkinson Building, Oxford, on March 14, 2016.

Professor Robert Brandenberger (McGill) argues that inflationary models still face considerable challenges. He discusses the relationship between inflationary models and particle physics, including string theory and examines alternatives to standard inflationary models. This lecture was conducted at the Dennis Sciama Theatre at the Denys Wilkinson Building, Oxford, on March 14, 2016.

Dr David Sloan (Oxford) discusses the for inflation to occur given typical initial conditions. He argues that, on the right understanding of the background dynamics of the universe, inflationary conditions dominate. This lecture was conducted at the Dennis Sciama Theatre at the Denys Wilkinson Building, Oxford, on March 14, 2016.

Professor Jerome Martin (Institut d’Astrophysique de Paris) explains the current state of evidence for inflationary models. He describes the variety of inflationary models, and discusses how Bayesian statistical methods apply to this space of theories. This lecture was conducted at the Dennis Sciama Theatre at the Denys Wilkinson Building, Oxford, on March 14, 2016.