The Fine-Tuning of the Universe for Intelligent Life

Abstract

The fine-tuning of the universe for intelligent life has received a great deal of attention in recent years, both in the philosophical and scientific literature. The claim is that in the space of possible physical laws, parameters and initial conditions, the set that permits the evolution of intelligent life is very small. I present here a review of the scientific literature, outlining cases of fine-tuning in the classic works of Carter, Carr and Rees, and Barrow and Tipler, as well as more recent work. To sharpen the discussion, the role of the antagonist will be played by Victor Stenger's recent book The Fallacy of Fine-Tuning: Why the Universe is Not Designed for Us. Stenger claims that all known fine-tuning cases can be explained without the need for a multiverse. Many of Stenger's claims will be found to be highly problematic. We will touch on such issues as the logical necessity of the laws of nature; objectivity, invariance and symmetry; theoretical physics and possible universes; entropy in cosmology; cosmic inflation and initial conditions; galaxy formation; the cosmological constant; stars and their formation; the properties of elementary particles and their effect on chemistry and the macroscopic world; the origin of mass; grand unified theories; and the dimensionality of space and time. I also provide an assessment of the multiverse, noting the significant challenges that it must face. I do not attempt to defend any conclusion based on the fine-tuning of the universe for intelligent life. This paper can be viewed as a critique of Stenger's book, or read independently.

77 pages, 9 figures. A condensed version of this paper has been accepted to appear in Publications of the Astronomical Society of Australia. Some small changes to match published version

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• Ab-initio Determination of Light Hadron Masses
• Dark Energy and Gravity
• Symmetries in Physics: Philosophical Reflections
• Dark Energy and Dark Gravity
• TASI Lectures on the Cosmological Constant
• A Finely-Predicted Higgs Boson Mass from A Finely-Tuned Weak Scale
• Testing anthropic predictions for Lambda and the CMB temperature
• Measure Problem for Eternal and Non-Eternal Inflation
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Cited by in corpus (24)

• Life at the Interface of Particle Physics and String Theory
• The Beginning and the End: The Meaning of Life in a Cosmological Perspective
• The Degree of Fine-Tuning in our Universe -- and Others
• Screams for Explanation: Finetuning and Naturalness in the Foundations of Physics
• Producing the Deuteron in Stars: Anthropic Limits on Fundamental Constants
• Alternative Explanations of the Cosmic Microwave Background: A Historical and an Epistemological Perspective
• Planets in Other Universes: Habitability constraints on density fluctuations and galactic structure
• $\theta$-dependence of light nuclei and nucleosynthesis
• Constraints on Alternate Universes: Stars and habitable planets with different fundamental constants
• Galaxy Formation Efficiency and the Multiverse Explanation of the Cosmological Constant with EAGLE Simulations
• On the Habitability of Universes without Stable Deuterium
• Sensitivity of Carbon and Oxygen Yields to the Triple-Alpha Resonance in Massive Stars
• Assessing, testing and estimating the amount of fine-tuning by means of active information
• Binding the Diproton in Stars: Anthropic Limits on the Strength of Gravity
• Is Cosmological Tuning Fine or Coarse?
• Stellar Helium Burning in Other Universes: A solution to the triple alpha fine-tuning problem
• On the wall velocity dependence of electroweak baryogenesis
• Constraints on Vacuum Energy from Structure Formation and Nucleosynthesis
• Defending The Fallacy of Fine-Tuning
• The Fine-Tuning Argument
• An introduction to gravitational waves through electrodynamics: a quadrupole comparison
• On a Relation of Vacuum Energy to the Hierarchy of Forces
• A Natural Introduction to Fine-Tuning
• Review of Geraint F. Lewis and Luke A. Barnes, A Fortunate Universe: Life in a Finely Tuned Cosmos