## Tags - Topics: - Additional: ## Definitions - [[Theory of Everything]] solving [[Quantum gravity]] or other ways of unifying [[Theory of relativity]] with [[Quantum mechanics]] through for example [[Emergence]], alternatively also unifying [[Fundamental forces|fundamental forces]]. ## Motivation - [[Quantum field theory]] is almost a [[Theory of Everything]], but it hasn't solved all problems in [[Physics]], such as [[Quantum gravity]] and others. ## Main resources - <iframe src="https://en.wikipedia.org/wiki/" allow="fullscreen" allowfullscreen="" style="height:100%;width:100%; aspect-ratio: 16 / 5; "></iframe> ## Landscapes - [Quantum Gravity Explained in 9 Slides - YouTube](https://www.youtube.com/watch?v=d-86tNCSJsg&t=373s) <iframe title="Quantum Gravity Explained in 9 Slides" src="https://www.youtube.com/embed/d-86tNCSJsg?feature=oembed" height="113" width="200" allowfullscreen="" allow="fullscreen" style="aspect-ratio: 1.76991 / 1; width: 100%; height: 100%;"></iframe> - By subproblems - solve [[Quantum gravity]] - additionally to [[Standard Model of Particle Physics]] [[Quantum field theory]], unify general [[Theory of relativity]] with [[Quantum mechanics]] - [[Classical]] from [[quantum]], [[Theory of relativity]] emerging from [[Quantum mechanics]] - [[Quantum Darwinism]] - [[Sean Caroll’s physics project]] - unify all other [[Fundamental forces|fundamental forces]] - find alternative to [[Standard Model of Particle Physics]] - [[String theory]] - [[Loop Quantum Gravity]] - [[Wolfram’s Theory of Everything]] - [[Omnidisciplinarity]] ## Brain storming - [Beff Jezos](https://twitter.com/BasedBeffJezos/status/1751363140514947286?t=6HWzBMpLjvrMn8hTPEcYnQ&s=19): Solving for the [[Theory of Everything in Fundamental Physics]] comes down to latent model hyperparameter inference for the laws of [[Physics]], where tests of these hyperparameters unfortunately lie beyond our currently observable / testable band of [[energy|energies]]. In order to get answers, we will have to ascend the [[Kardashev scale]]. This ascent will unlock perception into this higher energy band. Then we will need the [[Intelligence]] to understand what we see. [[Electricity generation]] + [[Artificial Intelligence]] scaling are the truly [[fundamental]] missions. ## Related - [[Theory of Everything in All of Physics]] ## Written by AI (may include factually incorrect information) Here's a comprehensive overview of various **Theories of Everything** (ToEs) proposed to unify the fundamental forces and particles in physics: 1. **Standard Model of Particle Physics** - **Description:** The well-established framework describing three of the four fundamental forces (electromagnetic, weak, and strong interactions) and classifying all known elementary particles. - **Limitations:** Does not incorporate gravity and cannot explain dark matter or dark energy. 2. **General Relativity** - **Description:** Einstein's theory explaining gravity as the curvature of spacetime caused by mass and energy. - **Limitations:** Incompatible with quantum mechanics at very small scales (Planck scale). 3. **Grand Unified Theories (GUTs)** - **Description:** Theories attempting to merge the electromagnetic, weak, and strong nuclear forces into a single force. - **Examples:** SU(5), SO(10), and E6 models. - **Limitations:** Do not include gravity and lack experimental confirmation. 4. **Supersymmetry (SUSY)** - **Description:** Proposes a symmetry between fermions and bosons, predicting superpartner particles for all known particles. - **Purpose:** Aims to solve hierarchy problems and facilitate unification in GUTs and string theory. 5. **String Theory** - **Description:** Suggests that fundamental particles are one-dimensional "strings" whose vibrations determine particle properties. - **Key Concepts:** Requires extra spatial dimensions; unifies gravity with other forces. - **Variants:** Type I, Type IIA, Type IIB, Heterotic SO(32), Heterotic \( E_8 \times E_8 \). 6. **M-Theory** - **Description:** An extension of string theory in 11 dimensions, proposed to unify all five superstring theories. - **Key Concepts:** Introduces membranes (branes) and higher-dimensional objects. 7. **Loop Quantum Gravity (LQG)** - **Description:** Attempts to quantize gravity using spin networks without extra dimensions. - **Key Concepts:** Space is quantized; geometry has a discrete structure. 8. **Twistor Theory** - **Description:** Developed by Roger Penrose, reformulates spacetime geometry using complex numbers called twistors. - **Purpose:** Seeks a quantum theory of gravity. 9. **Causal Dynamical Triangulations (CDT)** - **Description:** Models spacetime as a fabric built from simple building blocks (simplices) that evolve dynamically. - **Goal:** Reconcile general relativity and quantum mechanics. 10. **Non-Commutative Geometry** - **Description:** Modifies spacetime coordinates to not commute, leading to new physics at small scales. - **Applications:** Provides a framework for unifying gravity with quantum mechanics. 11. **Holographic Principle** - **Description:** Proposes that all information within a volume can be described by information on its boundary. - **Implications:** Leads to the AdS/CFT correspondence in string theory. 12. **E8 Theory** - **Description:** Garrett Lisi's attempt to unify all particles and forces within the mathematical structure of the E8 Lie group. - **Status:** Highly speculative and lacks empirical support. 13. **Causal Set Theory** - **Description:** Posits that spacetime is a discrete set of events ordered by causality. - **Objective:** Provide a quantum gravity framework. 14. **Emergence Theory** - **Description:** Suggests spacetime and gravity emerge from more fundamental quantum information processes. - **Key Concepts:** Leverages quantum entanglement and information theory. 15. **Supergravity** - **Description:** Combines supersymmetry with general relativity. - **Role:** Acts as a low-energy limit of M-theory. 16. **AdS/CFT Correspondence** - **Description:** A duality between a gravity theory in Anti-de Sitter space and a conformal field theory on its boundary. - **Significance:** Provides insights into quantum gravity and black hole physics. 17. **Quantum Graphity** - **Description:** Models spacetime as a dynamic graph that evolves and where geometry emerges from connectivity. - **Goal:** Explain spacetime emergence from quantum mechanics. 18. **Simulated Reality Theories** - **Description:** Hypothesize that reality is a simulation, often discussed in philosophical contexts. - **Considerations:** Raises questions about the nature of consciousness and reality. 19. **Variable Speed of Light Theories** - **Description:** Propose that the speed of light may have been different in the early universe. - **Implications:** Offers alternative explanations for cosmological observations. 20. **Preon Theory** - **Description:** Suggests that quarks and leptons are made up of more fundamental particles called preons. - **Challenges:** Lacks experimental evidence. 21. **Cellular Automata Approaches** - **Description:** Stephen Wolfram's idea that the universe operates like a computational system based on simple rules. - **Objective:** Derive physical laws from computational principles. 22. **Quantum Gravity Approaches** - **Spin Foam Models:** Extend LQG by incorporating spacetime histories. - **Group Field Theory:** Combines aspects of quantum field theory and LQG. - **Asymptotic Safety:** Proposes that gravity becomes safe from divergences at high energies. 23. **Entropic Gravity** - **Description:** Erik Verlinde's theory that gravity is an emergent force arising from entropy changes. - **Perspective:** Gravity results from informational physics. 24. **Extra Dimensions Theories** - **Kaluza-Klein Theory:** Unifies gravity and electromagnetism via a fifth dimension. - **Brane World Scenarios:** Our universe is a "brane" within higher-dimensional space. - **Randall-Sundrum Models:** Address hierarchy problems using warped extra dimensions. 25. **Quantum Geometry** - **Description:** Studies discrete spacetime structures at the Planck scale. - **Approach:** Utilizes mathematical frameworks like non-commutative geometry. --- These theories represent humanity's quest to understand the fundamental nature of reality by unifying all physical phenomena under a single theoretical framework. Research continues, with experimental tests and observations guiding the validation or refutation of these models. Sure, here's a comprehensive overview mapping out various "theories of everything" (TOEs) that aim to unify all fundamental forces and particles in the universe into a single, all-encompassing framework. --- ### **1. Classical Theories** - **Newtonian Mechanics**: Describes motion and gravitational forces at macroscopic scales. - **Maxwell's Electromagnetism**: Unifies electricity and magnetism into a single electromagnetic force. ### **2. Relativity Theories** - **Special Relativity (Einstein, 1905)**: Unifies space and time into spacetime, addressing high-speed motion. - **General Relativity (Einstein, 1915)**: Describes gravity as the curvature of spacetime caused by mass and energy. ### **3. Quantum Mechanics** - **Quantum Theory**: Explains the behavior of particles at atomic and subatomic levels, introducing wave-particle duality. - **Quantum Field Theory (QFT)**: Combines quantum mechanics with special relativity; the foundation for the Standard Model. ### **4. The Standard Model of Particle Physics** - **Electroweak Theory**: Unifies electromagnetic and weak nuclear forces. - **Quantum Chromodynamics (QCD)**: Describes the strong nuclear force. - **Limitations**: Does not include gravity and cannot explain dark matter or dark energy. ### **5. Grand Unified Theories (GUTs)** - **SU(5) and SO(10) Models**: Propose unification of electromagnetic, weak, and strong forces at high energies. - **Challenges**: Predict phenomena like proton decay, which hasn't been observed; exclude gravity. ### **6. Supersymmetry (SUSY)** - **Concept**: Every particle has a superpartner with different spin properties. - **Goal**: Resolve hierarchy problems in the Standard Model and aid in unification efforts. - **Status**: No experimental evidence found yet. ### **7. String Theory** - **Fundamentals**: Proposes that particles are one-dimensional "strings" vibrating at different frequencies. - **Types**: - **Bosonic String Theory** - **Superstring Theory** - **M-Theory**: Suggests an 11-dimensional universe. - **Features**: - **Extra Dimensions**: Requires additional spatial dimensions beyond the familiar three. - **Dualities**: Different string theories are interconnected. ### **8. Loop Quantum Gravity (LQG)** - **Objective**: Quantize spacetime itself without extra dimensions. - **Key Concepts**: - **Spin Networks**: Spacetime is composed of finite loops woven into a network. - **Discrete Space**: Space is not continuous but made up of tiny, discrete chunks. ### **9. Twistor Theory** - **Developed by**: Roger Penrose. - **Concept**: Reframes the geometry of spacetime using twistors, aiming to unify quantum mechanics and general relativity. ### **10. Non-Commutative Geometry** - **Pioneered by**: Alain Connes. - **Idea**: Generalizes geometry where coordinates do not commute, potentially describing spacetime at quantum scales. ### **11. Causal Dynamical Triangulations (CDT)** - **Approach**: Uses a lattice of simplices to model quantum spacetime. - **Result**: Emergent spacetime dimensions consistent with observed reality. ### **12. Emergent Gravity Theories** - **Entropic Gravity**: Proposes gravity is an emergent phenomenon from thermodynamic principles. - **Holographic Principle**: Suggests all information within a volume can be described by information on its boundary. ### **13. Asymptotically Safe Gravity** - **Concept**: Proposes that gravity remains consistent and predictable at high energies due to a non-trivial ultraviolet fixed point. ### **14. E8 Theory** - **Proposed by**: Garrett Lisi. - **Framework**: Attempts to unify all forces and particles using the E8 Lie group structure. - **Status**: Largely speculative with mathematical challenges. ### **15. Supergravity** - **Combines**: Supersymmetry and general relativity. - **Aim**: Integrate gravity into the framework of quantum field theory. ### **16. Quantum Graphity** - **Idea**: Space emerges from a network of discrete quantum bits (graphity). - **Goal**: Explain spacetime as an emergent property from quantum interactions. ### **17. Causal Set Theory** - **Approach**: Models spacetime as a discrete set of events ordered by causality. - **Implication**: Spacetime continuum emerges from fundamental discrete elements. ### **18. Group Field Theory** - **Combines**: Aspects of loop quantum gravity and quantum field theory. - **Objective**: Formulate quantum gravity in terms of fields over group manifolds. ### **19. Ads/CFT Correspondence** - **Discovered by**: Juan Maldacena. - **Principle**: Relates a gravity theory in Anti-de Sitter space to a conformal field theory on the boundary. - **Significance**: Provides insights into quantum gravity and black hole physics. ### **20. Multiverse Theories** - **Landscape of String Theory**: Predicts a vast number of possible vacua, each with different physical laws. - **Anthropic Principle**: Our universe has the properties that allow life because we are here to observe it. ### **21. Approaches Beyond Physics** - **Mathematical Universe Hypothesis**: Max Tegmark's idea that the universe is a mathematical structure. - **Digital Physics**: Suggests that the universe is computable and information-based. --- **Challenges and Considerations:** - **Experimental Verification**: Many TOEs make predictions currently beyond our technological capabilities. - **Mathematical Complexity**: Advanced and sometimes speculative mathematics are involved. - **Philosophical Implications**: Raises questions about the nature of reality, existence, and observability. **Interconnections:** - Many of these theories are not mutually exclusive and often inform or integrate aspects of one another. - **String Theory and Loop Quantum Gravity**: Different approaches to quantum gravity, potentially reconcilable under a broader framework. - **Holographic Principles**: Appear in both string theory and black hole thermodynamics. --- This map illustrates the vast landscape of theoretical physics in the quest for a unified understanding of the universe. Each theory offers unique insights and faces its own set of challenges, reflecting the complexity of unifying all fundamental aspects of reality under a single coherent framework.