What's wrong with physics? | Sabine Hossenfelder

The Institute of Art and Ideas

10 Jun 202135:11

EducationalLearning

32 Likes 10 Comments

TLDRThe speaker discusses the foundational challenges in physics, such as dark matter, quantum gravity, and the quantum measurement problem. They critique the reliance on 'beauty' as a criterion for theoretical development, highlighting numerous failed predictions based on aesthetic preferences. Instead, they advocate for focusing on resolving theoretical inconsistencies, drawing on historical examples of physics breakthroughs that stemmed from such resolutions.

Takeaways

🌌 The existence of dark matter is postulated to explain inconsistencies in astronomical observations when using only the matter we know from Earth.
🔍 Modified gravity theories propose alternative explanations for cosmic phenomena instead of invoking dark matter.
🤔 Quantum properties of space and time remain undefined, creating a mathematical inconsistency between quantum mechanics and general relativity.
📈 The measurement problem in quantum mechanics is unresolved, as the theory does not adequately explain the measurement process.
🚀 Despite over a century of general relativity and decades of the standard model, foundational physics has seen no significant updates.
📚 The lack of progress on foundational problems like dark matter and quantum gravity is a concern, given the exponential growth in the number of physicists.
💭 Physicists' reliance on 'beauty' as a criterion for developing theories has led to many failed predictions and stagnation in the field.
🎨 The pursuit of beautiful theories often leads to more complex models that evade experimental verification rather than being confirmed.
🔄 Failed predictions like the invisible axion, supersymmetric particles, and the unchanging nature of the universe have not deterred physicists from pursuing beautiful theories.
📖 Historically, successful theories in physics were not necessarily the ones guided by beauty, and many aesthetically pleasing ideas failed.
🚦 Physicists should focus on resolving inconsistencies within theories rather than seeking beauty as a benchmark for developing new models.

Q & A

What is the main inspiration behind the talk?
-The main inspiration behind the talk is a quote by Leonard Cohen, which discusses the idea that cracks in things allow light to enter, metaphorically relating this to the cracks in the foundations of physics.
What are the pressing problems in the foundations of physics mentioned in the transcript?
-The pressing problems in the foundations of physics mentioned include dark matter, the lack of a quantum theory for space and time (quantum gravity), and the quantum measurement problem.
What is dark matter and why is it proposed?
-Dark matter is a hypothetical form of matter that is proposed to explain certain observations in the universe, such as the velocities of galaxies and galaxy clusters, which cannot be accounted for by the known types of matter. It is called 'dark' because it does not interact with light and is therefore invisible.
What is the alternative to dark matter in explaining cosmic observations?
-The alternative to dark matter is the idea of modified gravity, which suggests that gravity works differently than what Einstein's general theory of relativity teaches us.
What is the issue with the quantum properties of space and time?
-The issue with the quantum properties of space and time is that our current theories, such as general relativity, do not account for quantum properties, leading to inconsistencies when trying to understand how space-time curvature is affected by quantum particles that can be in multiple places at once.
What is the significance of the cosmological constant in the context of the universe's expansion?
-The cosmological constant is a constant of nature that determines the expansion of the universe. Its positive value indicates that not only is the universe expanding, but this expansion is accelerating.
Why is the lack of progress in the foundations of physics concerning?
-The lack of progress is concerning because despite the exponential increase in the number of physicists and the amount of working hours, there has been a stagnation in solving fundamental problems like dark matter and quantum gravity. This stagnation may indicate a flawed methodology.
What is the speaker's critique of using beauty as a criterion in physics?
-The speaker criticizes the use of beauty as a criterion in physics because it has led to the development of complex theories that often fail to be confirmed by experimental evidence. The speaker argues that historical success was not due to reliance on beauty but rather from resolving inconsistencies in theories.
What historical examples does the speaker provide to illustrate the failure of beautiful theories?
-The speaker provides examples such as the idea that the orbits of planets are determined by polyhedra, the belief that celestial objects must move on circular orbits, and the attempts by prominent physicists like Heisenberg, Eddington, and Einstein to develop unified theories based on beauty, all of which turned out to be incorrect.
What does the speaker recommend as a better approach for progress in physics?
-The speaker recommends focusing on resolving inconsistencies in theories rather than relying on beauty as a criterion. They suggest that progress in physics can be driven by experimental breakthroughs or by resolving theoretical inconsistencies that lead to testable predictions.
How does the speaker describe the current state of physics research?
-The speaker describes the current state of physics research as stagnant, with an obsession with beauty leading to unpromising theories and a lack of positive experimental evidence for new phenomena.

Outlines

00:00

🌌 The Cracks in the Foundations of Physics

The speaker begins by drawing inspiration from Leonard Cohen's quote about cracks allowing light to enter, and uses this metaphor to discuss the unresolved issues in the foundations of physics. These include dark matter, the lack of a quantum theory for gravity, and the quantum properties of space and time. The speaker emphasizes that despite extensive observational evidence supporting our current theories, there are still significant puzzles that require answers, indicating gaps in our understanding of the universe.

05:00

🏗️ The Foundations of Physics: An Overview

The speaker clarifies what is meant by the 'foundations of physics,' focusing on areas where natural laws are not derived from any underlying theory. This includes general relativity, which describes gravity as a curvature of space-time, and quantum mechanics or quantum field theories, which describe the behavior of particles and their interactions. The speaker notes that while these theories are over a century old and have seen some minor adjustments, they have remained largely unchanged, and no significant progress has been made on the foundational problems mentioned earlier.

10:01

📈 The Slow Progress in Physics: A Concern

The speaker expresses concern about the slow progress in physics, particularly in addressing the foundational problems. Despite the increasing number of physicists and the exponential growth in the field, there has been a stagnation in solving these deep-rooted issues. The speaker argues that the reliance on beauty as a criterion for developing theories has led to numerous failed predictions and a lack of methodological change. They suggest that the obsession with beauty is a bad scientific approach and has contributed to this stagnation.

15:02

🎨 The Misguided Role of Beauty in Theoretical Physics

The speaker critiques the use of beauty as a guiding principle in physics, arguing that it has historically led to incorrect predictions and failed theories. They provide examples of theories that were considered beautiful but ultimately proved wrong, such as the idea that the orbits of planets are determined by polyhedra or that the universe is unchanging. The speaker asserts that beauty should not be the starting point for constructing theories, but rather the end result of scientific investigation, and that focusing on resolving inconsistencies in theories is a more fruitful approach.

20:03

🚧 Recommendations for Progress in Theoretical Physics

The speaker concludes by recommending that physicists should focus on resolving inconsistencies in theories rather than seeking beauty. They argue that historical progress in physics has come from resolving theoretical inconsistencies, such as the development of electromagnetic waves, special relativity, general relativity, and quantum field theories. The speaker suggests that addressing the current foundational problems in physics, such as dark matter, quantum gravity, and the quantum measurement problem, should be the priority, rather than pursuing aesthetically pleasing but unproven theories.

Mindmap

Keywords

💡Dark Matter

Dark Matter refers to a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe. It is invisible and does not interact with electromagnetic radiation, making it difficult to detect directly. In the video, the speaker discusses dark matter as one of the pressing problems in the foundations of physics, highlighting our inability to explain certain cosmic phenomena using only the matter we've observed on Earth.

💡Quantum Gravity

Quantum Gravity is a theoretical framework that attempts to reconcile the principles of quantum mechanics with those of general relativity, the latter of which describes gravity. The goal is to create a unified theory that can explain the behavior of particles at the smallest scales, including how they interact with gravity. The speaker in the video points out that we currently do not have a theory of quantum gravity, which is seen as a significant gap in our understanding of the universe.

💡Quantum Measurement Problem

The Quantum Measurement Problem refers to the challenge of understanding how the wave function of a quantum system collapses to a definite state when a measurement is made. This is a fundamental problem in quantum mechanics because the theory does not provide a clear explanation for what constitutes a measurement or how the act of measurement causes this collapse. The speaker in the video mentions this as one of the cracks in the foundations of physics, indicating that our current theories are incomplete.

💡Naturalness

Naturalness is a criterion used in theoretical physics to assess the aesthetic appeal or simplicity of a theory. It suggests that a theory is more 'natural' if it does not contain arbitrary parameters or small numbers that seem to be fine-tuned. The speaker argues that the pursuit of naturalness, as a form of beauty in theories, has led to a stagnation in physics because it is based on metaphysical requirements rather than empirical evidence.

💡Axion

The Axion is a hypothetical particle proposed to solve the strong CP problem in quantum chromodynamics, which is related to the lack of observed CP violation in strong interactions. Initially proposed as a visible particle, it was later modified into an 'invisible axion' to evade experimental constraints. Despite extensive searches, no axions have been detected, leading to questions about the validity of the approach based on beauty or naturalness.

💡Supersymmetry

Supersymmetry, or SUSY, is a theoretical concept in particle physics that proposes a symmetry between fermions and bosons, suggesting that for every known particle, there is a corresponding 'supersymmetric' partner with different spin properties. Supersymmetry was introduced to address issues in the standard model, such as the hierarchy problem, and was expected to be confirmed by experiments at the Large Hadron Collider. However, no supersymmetric particles have been found, leading to skepticism about the theory.

💡Cosmological Constant

The Cosmological Constant, denoted by the Greek letter Lambda (Λ), is a term in Einstein's field equations of general relativity that represents a form of energy density filling space homogeneously. It is associated with the idea that the vacuum of space has an energy that contributes to the expansion of the universe. The speaker mentions that the cosmological constant, once thought to be zero, has been found to have a small positive value, which has significant implications for the expansion of the universe.

💡Inconsistencies in Theories

Inconsistencies in Theories refer to the discrepancies or contradictions that arise within a scientific framework, indicating that the current understanding is incomplete or incorrect. Resolving these inconsistencies often leads to significant breakthroughs in science. The speaker argues that focusing on resolving these inconsistencies, rather than on aesthetic criteria like beauty, is a more fruitful approach in physics.

💡Stagnation in Physics

Stagnation in Physics refers to the perceived lack of progress or breakthroughs in the foundational areas of the discipline. The speaker suggests that the reliance on beauty as a criterion for theory assessment has contributed to this stagnation, as it has led to the proliferation of untested and untestable hypotheses.

💡Lost in Math

Lost in Math is a book by the speaker, which discusses the challenges and issues faced by theoretical physics, particularly focusing on the lack of empirical evidence for many proposed theories. The book critiques the current approach in theoretical physics and suggests that a more empirical, data-driven methodology is needed to make progress.

💡Aesthetic Appeal in Theories

Aesthetic Appeal in Theories refers to the tendency of physicists to prefer theories that are mathematically elegant or beautiful. This preference is often based on the belief that nature's underlying principles will be reflected in the symmetry and simplicity of the mathematical descriptions of those principles. The speaker argues that this preference for beauty has not proven to be a reliable guide to truth and has led to the proposal of many untested theories.

Highlights

The talk begins with inspiration from Leonard Cohen's quote about cracks letting the light in, metaphorically discussing the cracks in the foundations of physics.

Dark matter is introduced as a concept to explain inconsistencies in astronomical observations when using only the matter we know from Earth.

The possibility of modified gravity is mentioned as an alternative to dark matter to resolve discrepancies in our understanding of the cosmos.

The quantum properties of space and time are unknown, leading to inconsistencies when combining quantum mechanics with general relativity.

The need for a theory of quantum gravity is discussed to resolve the mathematical inconsistencies at the intersection of quantum mechanics and general relativity.

The problem of quantum mechanics not properly explaining the measurement process is highlighted.

The speaker defines the foundations of physics as areas dealing with natural laws that cannot be derived from any underlying theory, such as general relativity and quantum mechanics.

Despite over a century, there has been a lack of progress on the foundational problems in physics, leading to a perceived stagnation.

The speaker argues that the lack of progress is not due to the complexity of the problems but rather the methodology used by physicists, which relies heavily on the concept of beauty.

Historically, the belief in beautiful laws of nature was linked to the idea that they were created by a god, but this notion has persisted even after the removal of divine intervention from scientific thought.

Failed predictions based on the appeal to beauty, such as the axion and supersymmetric particles, are discussed, highlighting the lack of experimental evidence to support these theories.

The speaker emphasizes that relying on beauty in scientific theories is bad science, as history has shown no correlation between beauty and explanatory power.

The importance of resolving inconsistencies in theories is stressed as a more fruitful approach to making progress in physics.

The talk concludes with a recommendation for physicists to focus on resolving inconsistencies rather than pursuing theories based on aesthetic appeal.

The speaker's book, 'Lost in Math', is mentioned as a resource for further understanding of the issues discussed in the talk.

The transcript ends with a call to subscribe to the Institute of Art and Ideas for more debates, talks, and interviews.

Transcripts

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Related Tags

PhysicsFoundations DarkMatter QuantumGravity Inconsistencies ScientificMethodology BeautyInScience TheoreticalPhysics PhysicsHistory Axions DarkEnergy