# Physics

This & this Reddit thread are nice places to start learning physics. I like reading AskPhysics subreddit.

I found studying Roger Penrose's work most fascinating.

## Notesā

- What is energy?
- There's no satisfying definition beyond "the quantity that is conserved over time." This may sound arbitrary and ad hoc but it emerges from this deep mathematical principal called Noether's theorem that states that for each symmetry (in this case, staying the same while moving forward or backwards in time), there is something that is conserved. In this context, momentum is the thing that is conserved over distance, and angular momentum is the thing that is conserved through rotations.
- The less rigorous explanation is that it's essentially the currency used by physical systems to undergo change.

- One of the things you learn in Physics is that nothing is ever still or completely solid. All atoms vibrate and most(95+%) of their space is empty, where electrons spin. So everything you see is a vibrating mesh of molecules. Neutrinos are so small they can fly straight through everything, even planets! The only time anything stays completely still is at zero degrees Kelvin and it is theorized that time actually stands still at the this temperature.
- Emergent complexity: complexity arising from simple rules is interesting. One example of it is cellular automata and Conway's game of life.
- Gravity travels at the speed of light.
- Acceleration is independent of mass of object.
- Inertia is an intrinsic property and can basically be described as a bodyās resistance to acceleration/ change in itās speed (1st law). Whatās intertwined is inertia and force (not acceleration necessarily) since inertia (be it linear or rotational) of a particle would decide how much force is required to produce a certain acceleration (2nd law)
- The future is probability, the past is information, the passage of time is the collapse of one state to the other.
- Because atoms are actually 99.9999% (something similar to the degree) space, everything is also 99.9999% space but things cant pass through each other.
- All matter has kinetic and potential energy. It is easier to think of it as those are the only types of energy.
- Energy can change forms. From heat to potential to kinetic to radiation to heat.
- Gravity propagates at the speed of light.

## Linksā

- So You Want To Learn Physics... (HN)
- The Astonishing Simplicity of Everything
- The Map of Physics
- The Theoretical Minimum Courses - Theoretical Physics Education.
- Fun to Imagine
- Stephen Hawking had pinned his hopes on 'M-theory' to fully explain the universeāhere's what it is
- Ask HN: How to self-learn electronics?
- Conceptual illustration of time and space distortion near a mass
- Amazing Sand Pendulum
- Small physics lectures
- What in physics is fundamental?
- The World in UV
- Why does it take a million years for a photon moving at the speed of light to reach the sun's surface from its core?
- Why do I study Physics? (2013)
- Is Matter Conscious? (2017) (HN)
- The Mystery at the Bottom of Physics (2019)
- Ask HN: Physicists of HN, what are you working on these days? (2019)
- In conversation with Nima Arkani-Hamed (2014)
- A Peek into Einstein's Zurich Notebook
- David Tong: Lectures on Theoretical Physics
- Mathematics for Physics: Crash Course
- What are some of the "cornerstone books" in physics? (2019)
- The Feyman Lectures on Physics
- Principles of Optics - Electromagnetic theory of propagation, interference and diffraction of light.
- What Makes the Hardest Equations in Physics So Difficult? (2019)
- What are the minimum number of empirical observations/laws necessary to recover modern physics? (2020)
- Physics Travel Guide - Expository wiki which explains concepts in three levels of difficulty. We call these levels: intuitive, concrete and abstract. (HN)
- What is an area of physic that is grossly underrepresented? (2020)
- Why the foundations of physics have not progressed for 40 years (2020) (HN)
- Noetherās Theorem - A Quick Explanation (2019) (HN)
- Paul Dirac Interview, GĆ¶ttingen 1982
- Resources for the Physics Olympiad
- Snow Crystals (2019)
- Gears (2020) (HN)
- The Church-Turing Thesis and Physics (2019)
- Einstein Papers Project - Provides the first complete picture of Einsteinās massive written legacy.
- Intuitive and visual guide to understanding Maxwell's equations (HN)
- HEPML Resources - Listing of useful learning resources for machine learning applications in high energy physics (HEPML).
- Explorable Physics - Course notes for algebra based physics with explorable explanations. (Code)
- Ask HN: How to Self Study Physics? (2020)
- Information Is Physics (HN)
- Dr. Neil Turok - "From zero to infinity, and beyond!" (2012)
- Sir Roger Penrose - Plotting the Twist of Einsteinās Legacy (2020)
- Roger Penrose | Interview | Gravity, Hawking Points and Twistor Theory (2019)
- Why is Maxwellās Theory so hard to understand? (2007) (HN)
- How to learn quantum mechanics on your own (2019) (Video)
- Shining a Flashlight on Digital Holography (2020) (HN)
- HN: Scientists use the Tokyo Skytree to test general relativity (2020)
- The Biggest Ideas in the Universe (2020)
- Essays by Jakob Schwichtenberg
- Physics From Symmetry book (2015)
- No-Nonsense Books on Physics
- The Wolfram Physics Project (2020) (HN) (Video) (Article) (Code)
- The Wolfram Physics Project: The First Two Weeks (2020)
- Why Stephen Wolframās research program is a dead end (2020) (Reddit)
- A Class of Models with the Potential to Represent Fundamental Physics (Twitter)
- Why is the speed of light a constant?
- The Meaning of Einstein's Equation
- John Baezās research/blog
- Why is light slower in glass? - Sixty Symbols (2013)
- Quantum Fields: The Real Building Blocks of the Universe - David Tong (2017)
- David Tong's research papers
- Are quantum fields in any way similar to classical fields? (2020)
- QED: The Strange Theory of Light and Matter (2020) (Reddit)
- SIGGRAPH 2020 Technical Paper: N-Dimensional Rigid Body Dynamics (HN)
- A Mathematical Theory of Communication - Claude Shannon (1948)
- Brief introduction to the beauty of Information Theory (2020)
- Finding new physics will require a new particle collider (2020) (HN)
- Structure and Interpretation of Classical Mechanics (HN) (Code) (Web) (Exercises and notes)
- Evidence for Anyons, a Third Kingdom of Particles (2020) (HN)
- DIY Particle Detector - Mobile low-cost spectrometer for measuring radioactivity and the energy of ionising radiation like alpha particles and electrons. (HN)
- Speed of light is the speed limit relative to what? (2020)
- We have yet to experimentally confirm that the electric potential is physical (2020)
- Leonard Susskind lecture series
- What happens when photons collide? (2020)
- Mapping the Multiverse (2020)
- Photonic Crystals: Periodic Surprises in Electromagnetism
- MIT Mathematical Methods in Nanophotonics course notes
- Where in an atom exactly is a nucleus located? Is it in the centre or does its location vary from time to time? (2020)
- Ask HN: Without Einstein, would General Relativity be discovered by now? (2020)
- If breaking the sound barrier causes a sonic boom, what would breaking the light speed barrier do? (2020)
- If you were starting your physics PhD right now, what would you study? (2020)
- Some Frequently Asked Questions About Virtual Particles
- Applied Dynamical Systems (2020)
- What are some common misconceptions in physics? (2020)
- Papers by Edward Witten
- Feynman Lectures on the Strong Interactions (2020) (HN)
- What are good online resources for learning physics? (2020)
- What is a photon? (2017) (HN)
- Do gravitational waves destructively interfere with each other? (2020)
- The physics behind spring animations (2020)
- The Idea of Entropy Has Led Us Astray (2020) (HN)
- Do we need a Theory of Everything? (2020) (HN)
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- Two-beam Interference ā Collimated Beams
- NANOGrav - North American Nanohertz Observatory for Gravitational Waves. (Tweet)
- Algorithmic Theories of Everything (2000) (HN)
- Periodic table, color coded by the likely origin of each element (HN)
- Twistors and the Standard Model (2020)
- Spacetime has 3 space dimensions and 1 time dimension. Why?
- A flutter in time: Quantum mechanics is immune to the butterfly effect (2020) (HN)
- A brief introduction to observational entropy (2020)
- Humanly Traversable Wormholes (2020) (HN)
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- Symmetry Magazine - Dimensions of particle physics.
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- Mathematics for Physics - Illustrated Handbook.
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- Physics is stuck (2020) (HN)
- Manifestations of waves in nature (2020)
- Daniel and Jorge Explain the Universe - Most Common Listener Questions (2020)
- I am self-studying physics, which book should I get? (2020)
- A Childās Guide to Spinors (2016)
- NIST Pair of Atomic Clocks Reveal Einstein's Relativity at a Personal Scale (2010) (HN)
- The Grand Design by Stephen Hawking
- Moonshot Papers (2020)
- The Nobel Prize in Physics 2020 (HN)
- The Superpowers of Super-Thin Materials (2020) (HN)
- How Andrea Ghez won the Nobel for an experiment nobody thought would work (2020) (HN)
- Scientists find upper limit for the speed of sound (2020) (HN)
- Room-Temperature Superconductivity Achieved for the First Time (2020) (HN)
- Cantera - Chemical kinetics, thermodynamics, and transport tool suite. (Web) (Jupyter Examples)
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- What is relativity, anyway? (2020)
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- A New Map of the Standard Model of Particle Physics (2020) (HN) (HN)
- What is Energy? Is Energy conserved? (2020)
- Why no one has measured the speed of light (2020)
- How to Become a Good Theoretical Physicist
- Advance Electromagnetism Notes
- Penrose diagrams
- What Is a Particle? (2020) (HN)
- A Spacetime Surprise: Time Isnāt Just Another Dimension (2020) (HN)
- How Radiation Looks Like
- Visual demonstration of the power of sound to create order out of chaos
- Iām a pure mathematician who knows no physics. What should I read?
- 2020 Nobel Lectures in Physics
- Crystallography
- Peter Woit's Research
- Why The Speed Of Light Can't Be Measured (2020)
- One-way speed of light
- Well, Actually ā Physics Answers (HN)
- Heat Capacity and the Speed of Sound (2020)
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- Quanta Magazine: Physics
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- Why is light always moving?
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- What makes a physicist, a great physicist? (2021)
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- Reforming the Mathematical Language of Physics (2002)
- Sean Carroll's AMA (2021)
- Other than particles and waves, are there any other fundamental descriptors? (2021)
- EinsteinPy Project - Python package dedicated to problems arising in General Relativity and gravitational physics. (Code) (GitHub)
- ScienceClic English - YouTube
- List of Unsolved Problems in Physics
- Maps of Matter (2021) (HN)
- The Future of Matter - Notes on the striking things we're learning to do with matter.
- What do photons have to do with the electromagnetic force? (2021)
- Problems with Eric Weinstein's āGeometric Unityā (2021) (HN)
- Computation in Physical Systems
- Virtual Particles: What are they? (2011) (HN)
- Why Lagrangian Mechanics is Better than Newtonian Mechanics F=ma | Euler-Lagrange Equation (2021)
- Incoherent light sources (like a lightbulb) can actually be coherent at very small timescales
- Poster summarizing the standard model of particle physics (2021)
- Alternative interpretations of classical physics (2019) (HN)
- How does Hawking Radiation work? (2021)
- The Secret of Synchronization (2021)
- When Feynman Met Dirac (HN)
- The Koide Formula (2021)
- Leonard Susskind on Richard Feynman, the Holographic Principle, and Unanswered Questions in Physics (2018)
- Muon G-2 Experiment at Fermilab Finds Hint of New Particles (2021) (HN) (HN 2)
- This result could change physics forever (2021)
- Who are the current "rock stars" in physics? (2021)
- NEWS: What's up with Muons? - Sixty Symbols (2021) (Reddit)
- Can We Understand the Standard Model Using Octonions? (Tweet)
- The Wolfram Physics Project: A One-Year Update (2021) (HN)
- Collection of Videos in Support of Geometric Unity (Reddit)
- David Tong: Lectures on Particle Physics (Reddit)
- The Map of Particle Physics | The Standard Model Explained (2021)
- Statistical mechanics from entanglement: The Eigenstate Thermalization Hypothesis (2021) (Reddit)
- Are all forces illusions? (2020)
- Intersection-free Rigid Body Dynamics (2021)
- Gravity is a double copy of other forces (2021) (HN)
- Lectures on Geometrical Anatomy of Theoretical Physics
- An incomplete introduction to modern computational methods in physics part 1: Diagonalization (Reddit)
- What are the shortest, peer-reviewed articles in physics? (2021)
- Coanda Effect (2017)
- The Feynman Lectures on Physics (1964) (HN)
- The Feynman Lectures on Physics Audio Collection (HN)
- Scattering Theory of Waves and Particles (1982)
- Physics-informed neural networks with hard constraints for inverse design (2021) (Code)
- Of the physicists that are still 'alive,' what is the top 5 of physicists who has contributed more to our understanding of the universe? (2021)
- Simulation of photons refracting through a dispersive cylinder, by solution of the eikonal equation
- When did you realize you werenāt going to be an outstanding physicist. (2021)
- Does gravity bend gravity?
- Nanoscale and Quantum Photonics Lab
- Are the number of atoms in the universe fixed? (2021)
- The Quantum Theory of Fields Book (2013)
- Steven Weinberg's books on QFT (Reddit)
- What is Quantum Field Theory, and What Did We Think It Is? (1997) (Tweet)
- Steven Weinberg Has Died (2021) (HN)
- Steven Weinberg (1933-2021): a personal view
- Dreams of a Final Theory Book (1994) (Article)
- Online Course: Machine Learning for Physicists 2020 (Code)
- An Analytical, Statistical Approximate Solution for Dissipative and non-Dissipative Binary-Single Stellar Encounters (2021) (HN) (HN)
- What is the Chandrasekhar Limit? (2021)
- The Planck scale: Is there a fundamental limit to space and time? (2020)
- Deriving Einstein's most famous equation: Why does energy = mass x speed of light squared? (2021)
- Moments of Discovery - Tells the story of three scientific discoveries in the scientists' own words.
- Relativity: A Modern Primer (HN)
- Physics of Racing
- How strong would a magnetic field have to be to kill you? (HN)
- Physics ā© ML - Virtual hub at the interface of theoretical physics and deep learning.
- Physics-based Deep Learning (Paper)
- Why canāt I go faster than the speed of light? (2009) (HN)
- How can electrons be ātopologicalā? (2020)
- Scientists Create Matter From Pure Light, Proving the Breit-Wheeler Effect (2021) (Reddit) (HN)
- Physics for Engineers and Scientists Book (2003)
- UC Berkeley: PHYS 10 - Physics for Future Presidents (2017)
- New to Physics resources (2021)
- What a solid made of electrons looks like (2021) (HN)
- What hidden symmetry is controlling the Universe? (2021)
- The Nobel Prize in Physics 2021- Physics for climate and other complex phenomena (HN) (Reddit) (Tweet)
- Atomic resolution video of salt crystals forming in real time (2021) (HN)
- Five Things We Still Donāt Know About Water (2015) (HN)
- Nature Physics (Twitter)
- MIT Introduction to Special Relativity (2021)
- What does it mean for light to be a wave? (2021)
- Invariant Tensors in Gauge Theories (2018) (Tweet)
- Five mysteries the Standard Model canāt explain (2021) (HN)
- Symmetry Magazine - Dimensions of particle physics.
- Ultracold, superdense atoms become invisible (2021) (HN)
- Into the Cool: Energy Flow, Thermodynamics, and Life by Eric D. Schneider (2006)
- Gauss Linking Number and Electro-magnetic Uncertainty Principle (1997) (Tweet)
- Something Interesting about Albert Einsteinās Ph.D. Thesis
- Gravitation without the equivalence principle (2003)
- Gravitation without the equivalence principle (1957)
- Solver-in-the-Loop: Learning from Differentiable Physics to Interact with Iterative PDE-Solvers (2020) (Code)
- What Impossible Meant to Richard Feynman (2021) (HN)
- The Mystery of Snowflakes (2021)
- Gravitational waves should permanently distort space-time (2021) (HN)
- Oxford Physics Interview (2021)
- We all move at the Speed of Light (2018) (Reddit)
- The Year in Physics (2021) (Video)
- The Origins Of Constants Of Motion (2019)
- A delightful quirk of relativity theory (2022) (HN)
- The Joule-Thomson Effect and The Models We Know (2021)
- New lightweight material is stronger than steel (2022) (HN)
- Protons are probably smaller than long thought (2022) (HN)
- PDEs you should know (HN)
- How Einstein arrived at his theory of general relativity (HN)
- Why do electrons and protons have charge of exactly the same magnitude? (2022)
- What actually are electromagnetic waves? (2022)
- ŠŠ»Š°Š²Š½Š°Ń Š½Š°Š“ŠµŠ¶Š“Š° ŃŠµŠ¾ŃŠµŃŠøŃŠµŃŠŗŠ¾Š¹ ŃŠøŠ·ŠøŠŗŠø 21 Š²ŠµŠŗŠ°: Š”ŃŠæŠµŃŃŠøŠ¼Š¼ŠµŃŃŠøŃ (2022)
- Resources to self learn physics (2022)
- A deepening crisis forces physicists to rethink the structure of natureās laws (2022) (HN)
- What is the most surprising thing we don't know (in physics)? (2022)
- Negative Temperature (HN)
- Nonlinear Dynamics: Concise Introduction Interlaced with Code (2022) (Code)
- Misconceptions that are common among physics students (2022)
- ELI5: Why is a Planckās length the smallest possible distance?
- What I learned as a hired consultant to autodidact physicists (2016) (HN)
- Twenty-five years of nanoscale thermodynamics (2022) (Tweet)
- W boson mass may be 0.1% larger than predicted by the standard model (2022) (Reddit) (HN)
- Ludwig Boltzmann's inventions
- Faster-than-light communication - Wikipedia
- Collection of Database and Dataset Resources in Materials Science
- Lectures on Faster-than-Light Travel and Time Travel (2019) (HN)
- It took me 10 years to understand entropy (2022) (HN)
- Did the W-boson just ābreak the standard modelā? (2022) (HN)
- Nice resource for getting up to speed on physics (2022)
- Supersymmetry, explained visually (2022) (Reddit)