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February 7, 2023

  • Fine Tuning
    Jan 31, 2022 - By Miriam Frankel

    Imagine standing before a firing squad, with 50 trained marksmen aiming rifles at your heart. You’re certain that this is your last moment, but somehow the bullets all miss and you survive. Chances are you would feel perplexed about your survival and want to seek answers about how this happened. This metaphor was put forward by John Leslie to demonstrate how the existence of life in the universe similarly relies on improbable cosmic conditions, with physical variables seemingly aligning perfectly to enable the evolution of intelligent beings.


    Is our hospitable universe just a fluke? This review explores the complex history of research on fine tuning, including potential explanations—such as the anthropic principle, string theory, and the multiverse—attempts to pin down the key ingredients for life, and ways to test explanations for fine tuning.

    The review also examines claims by some physicists that any apparent fine tuning is an illusion. Some scientists have argued that in the absence of a probability distribution for the possible values of parameters that could occur, it’s impossible to argue with conviction that our measured values are actually odd. Another major issue is that we cannot rule out the possibility that some kind of life could arise even in a universe with completely different properties. And if one allows many parameters to vary simultaneously, it could alleviate the apparent fine-tuning problems, enabling the universe to produce life under a wider range of circumstances than first thought.

    So, is the universe ultimately fine-tuned for life?

    Downloadable Graphics

    Inflationary Multiverse
    by Maayan Harel

    Made in partnership with

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  • Emergence: A Review of Research on Condensed Matter and Quantum Gravity and Resonances Between These Fields
    Dec 31, 2021 - By George Musser

    In living organisms, complexity is immediately evident. But in simple objects, such as a balloon filled with air, the appearance is deceptive and masks complex inner workings. Outward simplicity is not in contradiction with inner complexity; in fact, one emerges from the other. A group of things can display features that are not found in any of their components. In many exotic materials, such as the wonder-material graphene, the properties of the whole are greater than the sum of the parts, potentially yielding tremendous practical applications.

    This review examines the concept of emergence in both condensed-matter systems and in quantum gravity, where physicists are exploring how quantum entanglement knits space into existence. It then identifies how theoretical developments in understanding the emergence of space have fed back into condensed matter, enriching both research areas and enabling scientists to solve the problems of one area by importing ideas from the other.

    Downloadable Graphics

    Hall Effects
    by Elfy Chiang

    Spacetime Holography
    by Maayan Harel

    Made in partnership with

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  • Time: A Review of Temporal Research in the Physical and Biological Sciences
    Nov 30, 2021 - By Kate Becker

    What is time?

    It is a position of the hands on a clock, and the difference between finding those hands in one position and another. You can be on time, in time, out of time. Time is the thing that makes the past closed and the future open, distinguishes history from prediction, and fixes cause before effect. It is the machine that turns the future into the present and the present into the past. It flows, but not steadily: sometimes it passes in a great rush, sometimes in drowsy drips, and sometimes it almost seems to freeze. It makes beginnings possible and endings inevitable.

    Today’s exquisitely precise timekeeping has brought us no closer to understanding the essential nature of time. Physicists are now tackling some of our deepest questions about time head-on: Where does it come from? Is the flow of time real, or an illusion? Why does time’s arrow point in only one direction? Can time be reversed? And how does the human mind perceive time?

    Meanwhile, the two great theories of modern physics, general relativity, describing the motion of the heavenly bodies, and quantum theory, describing the behavior of the very small, reveal contradictory faces of time. Ever since the two theories emerged in the early 20th century, physicists have been trying to find ways to unite them into a single, deeper theory of “quantum gravity.” Could this quest also uncover the true nature of time? This review describes some of the latest experiments to build a “quantum clock” that could reveal the answers.

    Downloadable Graphics

    Relativity of Simultnaeity
    by Maayan Harel

    Block Universe
    by Maayan Harel

    Double Slit
    by Maayan Harel

    Delayed Choice
    by Maayan Harel

    Time and the Brain
    by Elfy Chiang

    Made in partnership with

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  • Cosmological Origins
    Nov 15, 2021 - By M. Mitchell Waldrop, PhD

    They are some of the oldest questions that human beings have ever asked—renewed again and again by every child who looks up in wonder at the sun, the moon, the stars, and the planets: What are they? Why do they move and change the way they do? Where do they all come from? And where do we come from? These questions are so fundamental that every culture and every religion provides answers.

    Science, however, confines itself to puzzles that can be addressed by reason, experiment, and observation. Yet as we will see, that discipline has guided scientists to a cosmic story that is far stranger than our ancestors could have imagined. Again and again, what are now considered to be foundational discoveries were met with indifference, incomprehension, or even hostility—and achieved widespread acceptance only after accumulating evidence made the new ideas impossible to ignore.

    This review walks us through those paradigm shifts and introduces some of the major mysteries facing cosmologists today. We review how physicists established that the universe is expanding and derived the Big Bang model. But then we ask what might have happened before the Big Bang? What is inflation theory? Do we live in a multiverse of many universes? How are astronomers and physicists homing in on the identities of dark matter and dark energy, with new observations and lab experiments? And we discuss one of the biggest cosmic conundrums, the ‘Hubble tension’: Why do different astrophysical observations suggest different ages for our universe? Could resolving this mismatch force us to consider a new cosmological picture?

    Downloadable Graphics

    Inflationary Multiverse
    by Maayan Harel

    Hubble Tension
    by Maayan Harel

    Made in partnership with

    View report

  • Undecidability, Uncomputability, and Unpredictability
    Aug 21, 2021 - By Anthony Aguirre, Zeeya Merali & David Sloan (Eds)

    For a brief time in history, it was possible to imagine that a sufficiently advanced intellect could, given sufficient time and resources, in principle understand how to mathematically prove everything that was true. They could discern what math corresponds to physical laws, and use those laws to predict anything that happens before it happens.

    That time has passed. Gödel’s undecidability results (the incompleteness theorems), Turing’s proof of non-computable values, the formulation of quantum theory, chaos, and other developments over the past century have shown that there are rigorous arguments limiting what we can prove, compute, and predict. While some connections between these results have come to light, many remain obscure, and the implications are unclear. Are there, for example, real consequences for physics ― including quantum mechanics ― of undecidability and non-computability? Are there implications for our understanding of the relations between agency, intelligence, mind, and the physical world?

    This book, based on the winning essays from the annual FQXi competition, contains ten explorations of Undecidability, Uncomputability, and Unpredictability. The contributions abound with connections, implications, and speculations while undertaking rigorous but bold and open-minded investigation of the meaning of these constraints for the physical world, and for us as humans.

  • What is Fundamental?
    Mar 29, 2019 - By Anthony Aguirre, Brendan Foster & Zeeya Merali (Eds)

    Are there truly fundamental entities in nature? Or are the things that we regard as fundamental in our theories – for example space, time or the masses of elementary particles – merely awaiting a derivation from a new, yet to be discovered theory based on elements that are more fundamental?

    This was the central question posed in the 2018 FQXi essay competition, which drew more than 200 entries from professional physicists, philosophers, and other scholars. This volume presents enhanced versions of the fifteen award-winning essays, giving a spectrum of views and insights on this fascinating topic.

    From a prescription for “when to stop digging” to the case for strong emergence, the reader will find here a plethora of stimulating and challenging ideas - presented in a largely non-technical manner - on which to sharpen their understanding of the language of physics and even the nature of reality.

  • Wandering Towards a Goal
    Jun 11, 2018 - By Anthony Aguirre, Brendan Foster & Zeeya Merali (Eds)

    This collection of prize-winning essays addresses the controversial question of how meaning and goals can emerge in a physical world governed by mathematical laws. What are the prerequisites for a system to have goals? What makes a physical process into a signal? Does eliminating the homunculus solve the problem?

    The three winning essays, by Larissa Albantakis, Carlo Rovelli and Jochen Szangolies tackle exactly these challenges, while many other aspects (agency, the role of the observer, causality versus teleology, ghosts in the machine etc.) put in an appearance in the other award winning contributions.

    These seventeen imaginative, stimulating and often entertaining essays are enhanced versions of the prize-winning entries to the FQXi essay competition in 2017.

  • Trick or Truth
    Mar 10, 2016 - By Anthony Aguirre, Brendan Foster & Zeeya Merali (Eds)

    The prize-winning essays in this book address the fascinating but sometimes uncomfortable relationship between physics and mathematics.

    Is mathematics merely another natural science? Or is it the result of human creativity?

    Does physics simply wear mathematics like a costume, or is math the lifeblood of physical reality?

    The nineteen wide-ranging, highly imaginative and often entertaining essays are enhanced versions of the prize-winning entries to the FQXi essay competition “Trick or Truth”, which attracted over 200 submissions.

  • How Should Humanity Steer the Future?
    Sep 30, 2015 - By Anthony Aguirre, Brendan Foster & Zeeya Merali (Eds)

    The fourteen award-winning essays in this volume discuss a range of novel ideas and controversial topics that could decisively influence the course of human life on Earth.

    Their authors address, in accessible language, issues as diverse as: enabling our social systems to learn; research in biological engineering and artificial intelligence; mending and enhancing minds; improving the way we do, and teach, science; living in the here and now; and the value of play.

    The essays are enhanced versions of the prize-winning entries submitted to the Foundational Questions Institute (FQXi) essay competition in 2014.

  • It From Bit, or Bit From It?
    Mar 9, 2015 - By Anthony Aguirre, Brendan Foster & Zeeya Merali (Eds)

    The essays in this book look at the question of whether physics can be based on information, or – as John Wheeler phrased it – whether we can get “It from Bit”. They are based on the prize-winning essays submitted to the FQXi essay competition of the same name, which drew over 180 entries.

    The eighteen contributions address topics as diverse as quantum foundations, entropy conservation, nonlinear logic and countable spacetime.

    Together they provide stimulating reading for all physics aficionados interested in the possible role(s) of information in the laws of nature.


  • Questioning the Foundations of Physics
    Feb 5, 2015 - By Anthony Aguirre, Brendan Foster & Zeeya Merali (Eds)

    The essays in this book look at way in which the fundaments of physics might need to be changed in order to make progress towards a unified theory. They are based on the prize-winning essays submitted to the FQXi essay competition “Which of Our Basic Physical Assumptions Are Wrong?”, which drew over 270 entries.

    As Nobel Laureate physicist Philip W. Anderson realized, the key to understanding nature’s reality is not anything “magical”, but the right attitude, “the focus on asking the right questions, the willingness to try (and to discard) unconventional answers, the sensitive ear for phoniness, self-deception, bombast, and conventional but unproven assumptions.”

    The authors of the eighteen prize-winning essays have, where necessary, adapted their essays for the present volume so as to (a) incorporate the community feedback generated in the online discussion of the essays, (b) add new material that has come to light since their completion and (c) to ensure accessibility to a broad audience of readers with a basic grounding in physics.

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