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3 Perplexing Physics Problems

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  • 3 Perplexing Physics Problems

    14:00

    Why does shaken soda explode? Does ice melt first in fresh or salt water?
    Thank you Squarespace for sponsoring this video. Go to to save 10% off your first purchase of a website or domain using code: VERITASIUM

    This video features experiments that have been shown to me by science teachers over the years. Does ice melt fast in salt water or fresh water was an experiment introduced to me at the Utah Science Teachers' conference. The ring of metal over a chain demo came from a teachers event in Florida. The idea shaking a carbonated drink increases pressure came from an email.

    Special thanks to Petr Lebedev for building the pressure gauge.

    Links to literature are below:
    Victims of the pop bottle, by Ted Willhoft. New Scientist, 21 August 1986 p.28

    Carbonation speculation
    The Physics Teacher 30, 173 (1992);

    Agitation solution
    The Physics Teacher 30, 325 (1992);

    Filmed by Cristian Carretero, Jordan Schnabel, Jonny Hyman, and Raquel Nuno

    Music from Seaweed Quietly Tense Mind Shift Observations

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  • 5 Fun Physics Phenomena

    5:28

    Five cool physics tricks, but how do they work?
    Explanations:
    Check out Audible.com:
    Leave your ideas in the comments below or subscribe for the answers next week.

    Chris Hadfield in AUS:
    All tickets now sold out.

    The Cane Balance:
    Slide your fingers in from the ends of a horizontal cane to find its centre of mass.

    Shot and Edited by Pierce Cook at the YouTube Space LA.

    Music by Amarante:

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  • The Simplest Impossible Problem

    3:57

    A 7-year-old can understand this problem which completely baffles mathematicians.

    Collatz calculator:

  • The Bizarre Behavior of Rotating Bodies, Explained

    14:49

    Spinning objects have strange instabilities known as The Dzhanibekov Effect or Tennis Racket Theorem - this video offers an intuitive explanation.
    Part of this video was sponsored by LastPass, click here to find out more:

    References:
    Prof. Terry Tao's Math Overflow Explanation:

    The Twisting Tennis Racket
    Ashbaugh, M.S., Chicone, C.C. & Cushman, R.H. J Dyn Diff Equat (1991) 3: 67.

    Janibekov’s effect and the laws of mechanics
    Petrov, A.G. & Volodin, S.E. Dokl. Phys. (2013) 58: 349.

    Tumbling Asteroids
    Prave et al.

    The Exact Computation of the Free Rigid Body Motion and Its Use in Splitting Methods
    SIAM J. Sci. Comput., 30(4), 2084–2112
    E. Celledoni, F. Fassò, N. Säfström, and A. Zanna


    Animations by Iván Tello and Isaac Frame

    Special thanks to people who discussed this video with me:
    Astronaut Don Pettit
    Henry Reich of MinutePhysics
    Grant Sanderson of 3blue1brown
    Vert Dider (Russian YouTube channel)

    Below is a further discussion by Henry Reich that I think helps summarize why axes 1 and 3 are generally stable while axis 2 is not:

    In general, you might imagine that because the object can rotate in a bunch of different directions, the components of energy and momentum could be free to change while keeping the total momentum constant.

    However, in the case of axis 1, the kinetic energy is the highest possible for a given angular momentum, and in the case of axis 3, the kinetic energy is the lowest possible for a given angular momentum (which can be easily shown from conservation of energy and momentum equations, and is also fairly intuitive from the fact that kinetic energy is proportional to velocity squared, while momentum is proportional to velocity - so in the case of axis 1, the smaller masses will have to be spinning faster for a given momentum, and will thus have more energy, and vice versa for axis 3 where all the masses are spinning: the energy will be lowest). In fact, this is a strict inequality - if the energy is highest possible, there are no other possible combinations of momenta other than L2=L3=0, and vice versa for if the energy is the lowest possible.

    Because of this, in the case of axis 1 the energy is so high that there simply aren't any other possible combinations of angular momentum components L1, L2 and L3 - the object would have to lose energy in order to spin differently. And in the case of axis 3, the energy is so low that there likewise is no way for the object to be rotating other than purely around axis 3 - it would have to gain energy. However, there's no such constraint for axis 2, since the energy is somewhere in between the min and max possible. This, together with the centrifugal effects, means that the components of momentum DO change.

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  • The Secret of Synchronization

    20:58

    How does order spontaneously arise out of chaos? This video is sponsored by Kiwico — go to for 50% off your first month of any crate.

    An enormous thanks to Prof. Steven Strogatz — this video would not have been possible without him. Much of the script-writing was inspired and informed by his wonderful book Sync, and his 2004 TED talk. He is a giant in this field, and has literally written the book on chaos, complexity, and synchronization. It was hard to find a paper in this field that Steven (or one of his students) didn't contribute to. His Podcast The Joy of X is wonderful — please listen and subscribe wherever you get your podcasts

    Nicky Case's Amazing Firefly Interactive —

    Great Kuramoto Model Interactive —

    References:

    Strogatz, S. H. (2012). Sync: How order emerges from chaos in the universe, nature, and daily life. Hachette UK. —

    Strogatz, S. H. (2000). From Kuramoto to Crawford: exploring the onset of synchronization in populations of coupled oscillators. Physica D: Nonlinear Phenomena, 143(1-4), 1-20. —

    Goldsztein, G. H., Nadeau, A. N., & Strogatz, S. H. (2021). Synchronization of clocks and metronomes: A perturbation analysis based on multiple timescales. Chaos: An Interdisciplinary Journal of Nonlinear Science, 31(2), 023109. —

    The Broughton Suspension Bridge and the Resonance Disaster —

    Bennett, M., Schatz, M. F., Rockwood, H., & Wiesenfeld, K. (2002). Huygens's clocks. Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 458(2019), 563-579. —

    Pantaleone, J. (2002). Synchronization of metronomes. American Journal of Physics, 70(10), 992-1000. —

    Kuramoto, Y. (1975). Self-entrainment of a population of coupled non-linear oscillators. In International symposium on mathematical problems in theoretical physics (pp. 420-422). Springer, Berlin, Heidelberg. --

    Great video by Minute Earth about Tidal Locking and the Moon —

    Strogatz, S. H., Abrams, D. M., McRobie, A., Eckhardt, B., & Ott, E. (2005). Crowd synchrony on the Millennium Bridge. Nature, 438(7064), 43-44. —

    Zhabotinsky, A. M. (2007). Belousov-zhabotinsky reaction. Scholarpedia, 2(9), 1435. —

    Flavio H Fenton et al. (2008) Cardiac arrhythmia. Scholarpedia, 3(7):1665. —

    Cherry, E. M., & Fenton, F. H. (2008). Visualization of spiral and scroll waves in simulated and experimental cardiac tissue. New Journal of Physics, 10(12), 125016. —

    Tyson, J. J. (1994). What everyone should know about the Belousov-Zhabotinsky reaction. In Frontiers in mathematical biology (pp. 569-587). Springer, Berlin, Heidelberg. —

    Winfree, A. T. (2001). The geometry of biological time (Vol. 12). Springer Science & Business Media. —

    Special thanks to Patreon supporters: Mac Malkawi, Oleksii Leonov, Michael Schneider, Jim Osmun, Tyson McDowell, Ludovic Robillard, jim buckmaster, fanime96, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Lyvann Ferrusca, Alfred Wallace, Arjun Chakroborty, Joar Wandborg, Clayton Greenwell, Pindex, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

    Written by Derek Muller and Petr Lebedev
    Animation by Fabio Albertelli and Jakub Misiek
    Simulations and 3D Animation by Jonny Hyman
    Filmed by Derek Muller and Raquel Nuno
    Edited by Derek Muller
    Additional video supplied by Getty Images
    Thumbnail by Ignat Berbeci

    More footage from NASA's Scientific Visualization Studio

    100 metronome video from

    Intro animation by Jorge Cham

    Thanks for the BZ footage from SteinbockGroup: and
    NileRed

    Animation of waves in the heart from The Virtual Heart/ EM Cherry/ FH Fenton — and

    Chemical materials and protocol provided by Mike Morris and the UCI Chemistry Outreach Program

    Thanks to Alie Ward for title/thumbnail consultation
    Thanks to Dr Juliette Becker and Dr James O'Donoghue for the planetary science help

    Music from Jonny Hyman, Epidemic Sound Seaweed Deeper Than The Ocean Ripple Effect
    Music also from Artlist Children of Mystery

    Thumbnail by Ignat Berbeci

  • Can you solve the boat puzzle?

    4:52

    You throw a rock in water from your boat. Can you figure out what happens to the water level?

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    Host/Writer/Editor: Dianna Cowern

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  • Chaos: The Science of the Butterfly Effect

    12:51

    Chaos theory means deterministic systems can be unpredictable. Thanks to LastPass for sponsoring this video. Click here to start using LastPass:
    Animations by Prof. Robert Ghrist:

    Want to know more about chaos theory and non-linear dynamical systems? Check out:

    Butterfly footage courtesy of Phil Torres and The Jungle Diaries:
    Solar system, 3-body and printout animations by Jonny Hyman
    Some animations made with Universe Sandbox:
    Special thanks to Prof. Mason Porter at UCLA who I interviewed for this video.

    I have long wanted to make a video about chaos, ever since reading James Gleick's fantastic book, Chaos. I hope this video gives an idea of phase space - a picture of dynamical systems in which each point completely represents the state of the system. For a pendulum, phase space is only 2-dimensional and you can get orbits (in the case of an undamped pendulum) or an inward spiral (in the case of a pendulum with friction). For the Lorenz equations we need three dimensions to show the phase space. The attractor you find for these equations is said to be strange and chaotic because there is no loop, only infinite curves that never intersect. This explains why the motion is so unpredictable - two different initial conditions that are very close together can end up arbitrarily far apart.

    Music from The Longest Rest A Sound Foundation Seaweed

  • How An Infinite Hotel Ran Out Of Room

    6:07

    If there's a hotel with infinite rooms, could it ever be completely full? Could you run out of space to put everyone? The surprising answer is yes -- this is important to know if you're the manager of the Hilbert Hotel.

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    References: Ewald, W., & Sieg, W. (2013). David Hilbert's Lectures on the Foundations of Arithmetic and Logic 1917-1933. Springer Berlin Heidelberg. --

    Gamow, G. (1988). One, two, three--infinity: facts and speculations of science. Courier Corporation. --

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    Special thanks to Patreon supporters: Paul Peijzel, Crated Comments, Anna, Mac Malkawi, Michael Schneider, Oleksii Leonov, Jim Osmun, Tyson McDowell, Ludovic Robillard, jim buckmaster, fanime96, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Marinus Kuivenhoven, Alfred Wallace, Arjun Chakroborty, Joar Wandborg, Clayton Greenwell, Pindex, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

    ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀

    Animation by JD Pounds and Jonny Hyman
    Thumbnail by Iván Tello
    Music by Jonny Hyman and from Epidemic Sound and E's Jammy Jams (Hotel Lavish - Radio Nights, Steps in Time - Golden Age Radio, What Now - Golden Age Radio, Book Bag - E's Jammy Jams, Arabian Sand - E's Jammy Jams, Firefly in a Fairytale - Gareth Coker)
    Written By Derek Muller and Alex Kontorovich
    Sound Design by Jonny Hyman

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  • The Mind Bending Story Of Quantum Physics | Spark

    58:56

    Professor Jim Al-Khalili traces the story of arguably the most important, accurate and yet perplexing scientific theory ever: quantum physics.

    The story of quantum physics starts at the beginning of the 20th century with scientists trying to better understand how light bulbs work. This simple question soon led scientists deep into the hidden workings of matter, into the sub-atomic building blocks of the world around us. Here they discovered phenomena unlike any encountered before - a realm where things can be in many places at once, where chance and probability call the shots and where reality appears to only truly exist when we observe it.

    Albert Einstein hated the idea that nature, at its most fundamental level, is governed by chance. Jim reveals how in the 1930's, Einstein thought he'd found a fatal flaw in quantum physics. This was not taken seriously until it was tested in the 1960s. Professor Al-Khalili repeats this critical experiment, posing the question does reality really exist, or do we conjure it into existence by the act of observation?

    Elsewhere, we explore how the most famous law of quantum physics – The Uncertainty Principle – is obeyed by plants and trees as they capture sunlight during the vital process of photosynthesis. Could quantum mechanics explain the greatest mystery in biology - evolution?

    Content Provided By TVF International. Any Queries Please Contact Us at hello@littledotstudios.com

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  • 9 Real Things That Defy the Laws of Physics

    10:02

    For copyright matters please contact us at: copymanager.mn@gmail.com

    TechZone ►

    Let's be honest, not everyone in school enjoys exact sciences. However, you don't have to be an expert, or know Newton's three laws by heart to understand the basic principles of physics. After all, it is easy to understand that under the influence of gravity objects fall and a person cannot fly without special devices. Wait a minute... Are you sure? Today we'll talk about situations where the laws of physics don't apply.

  • The Most Common Cognitive Bias

    4:44

    Can you figure out the rule?
    Did you see the exponents pattern?
    Why do you make people look stupid?

    How do you investigate hypotheses? Do you seek to confirm your theory - looking for white swans? Or do you try to find black swans? I was startled at how hard it was for people to investigate number sets that didn't follow their hypotheses, even when their method wasn't getting them anywhere.

    In the video I say when people came to Australia... by which I meant, when Europeans who believed all swans were white came to Australia... I did not mean any offence to Indigenous Australians who were already in Australia at that time. Please accept my apologies for the poor phrasing if you were offended by it.

    This video was inspired by The Black Swan by Nassim Taleb and filmed by my mum. Thanks mum!

    Partly my motivation came from responses to my Facebook videos - social media marketers saying 'Facebook ads have worked for me so there can't be fake likes.' Just because you have only seen white swans, doesn't mean there are no black ones. And in fact marketers are only looking for white swans. They think it was invalid of me to make the fake Virtual Cat page: 'well of course if it's a low quality page you're going to get low quality likes.' But my point is this is black swan bait, something they would never make because their theory is confident in the exclusive existence of white swans.

  • Why No One Has Measured The Speed Of Light

    19:05

    Physics students learn the speed of light, c, is the same for all inertial observers but no one has ever actually measured it in one direction. Thanks to Kiwico for sponsoring this video. For 50% off your first month of any crate, go to

    Huge thanks to Destin from Smarter Every Day for always being open and willing to engage in new ideas. If you haven't subscribed already, what are you waiting for:

    For an overview of the one-way speed of light check out the wiki page:

    The script was written in consultation with subject matter experts:
    Prof. Geraint Lewis, University of Sydney
    Prof. Emeritus Allen Janis, University of Pittsburgh
    Prof. Clifford M. Will, University of Florida
    The stuff that's correct is theirs. Any errors are mine.

    References:
    Einstein, A. (1905). On the electrodynamics of moving bodies. Annalen der physik, 17(10), 891-921.
    (English) (German)

    Greaves, E. D., Rodríguez, A. M., & Ruiz-Camacho, J. (2009). A one-way speed of light experiment. American Journal of Physics, 77(10), 894-896.

    Response to Greaves et al. paper —
    Finkelstein, J. (2009). One-way speed of light?. arXiv, arXiv-0911.

    The Philosophy of Space and Time - Reichenbach, H. (2012). Courier Corporation.

    Anderson, R., Vetharaniam, I., & Stedman, G. E. (1998). Conventionality of synchronisation, gauge dependence and test theories of relativity. Physics reports, 295(3-4), 93-180.

    A review article about simultaneity — Janis, Allen, Conventionality of Simultaneity, The Stanford Encyclopedia of Philosophy (Fall 2018 Edition), Edward N. Zalta (ed.)

    Will, C. M. (1992). Clock synchronization and isotropy of the one-way speed of light. Physical Review D, 45(2), 403.

    Zhang, Y. Z. (1995). Test theories of special relativity. General Relativity and Gravitation, 27(5), 475-493.

    Mansouri, R., & Sexl, R. U. (1977). A test theory of special relativity: I. Simultaneity and clock synchronization. General relativity and Gravitation, 8(7), 497-513.

    Research and writing by Derek Muller and Petr Lebedev
    Animations by Ivàn Tello
    VFX, music, and space animations by Jonny Hyman
    Filmed by Raquel Nuno

    Special thanks for reviewing earlier drafts of this video to:
    Dominic Walliman, Domain of Science:
    Henry Reich, Minutephysics:
    My Patreon supporters

    Additional music from Observations 2

  • Mean Girls Math Problems And Solutions

    6:36

    The movie Mean Girls has 3 interesting math questions. This video presents the problems and their solutions.

    Solutions
    First problem: 1:28
    Second problem: 2:57
    Third problem (limit): 4:01

    Blog post:

    Power series approximation idea


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    Math Puzzles Volume 1 features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.4/5 stars on 13 reviews.


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    40 Paradoxes in Logic, Probability, and Game Theory contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews)


    The Best Mental Math Tricks teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 4 reviews)


    Multiply Numbers By Drawing Lines This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 3 reviews)

  • Why Gravity is NOT a Force

    17:34

    The General Theory of Relativity tells us gravity is not a force, gravitational fields don't exist. Objects tend to move on straight paths through curved spacetime. Thanks to Caséta by Lutron for sponsoring this video. Find out more at:

    Huge thanks to Prof. Geraint Lewis for hours of consulting on this video so I could get these ideas straight in my own brain. Check out his YouTube channel: or his books:

    Amazing VFX, compositing, and editing by Jonny Hyman
    2D animations by Ivàn Tello
    Filmed by Steven Warren and Raquel Nuno
    Special thanks to Petr Lebedev for reviews and script consultation
    Music by Jonny Hyman and from Epidemic Sound

    Rocket made by Goodnight and Co.
    Screen images in rocket by Geoff Barrett

    Slow motion rocket exhaust footage from Joe Barnard at BPS.Space

  • What Happened At The Beginning Of Time? - with Dan Hooper

    51:33

    We’re learning more and more about the recent history of our universe, but how much do we really know about its very first few seconds?
    Dan’s book At The Edge Of Time is available now -

    Watch the Q&A:

    Ever since Edwin Hubble observed that the universe was expanding in 1929, cosmologists have had their work cut out for them trying to solve the seemingly impossible questions arising from the time immediately after the Big Bang.

    In this talk Dan Hooper explores the perplexing problems surrounding the secrets of the early universe, and the far-reaching implications some of the answers might have for the understanding of the universe we think we have today.

    Dan Hooper is Senior Scientist and the Head of the Theoretical Astrophysics Group at the Fermi National Accelerator Laboratory. He is also an Associate Professor in the Department of Astronomy and Astrophysics at the University of Chicago. Previously, he was the David Schramm Fellow at Fermilab, and a postdoc at the University of Oxford. In 2003, he completed his PhD in physics at the University of Wisconsin.

    This talk was filmed in the Ri on 10 February 2020.

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  • Bayes Theorem and some of the mysteries it has solved

    16:18

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  • The Train Fly Problem - A Classic Math Puzzle

    6:46

    A fly, moving at 40 mph, zigzags back and forth between two trains, each moving at 20 mph. If the trains are 100 miles apart initially, how much distance will the fly travel? The genius mathematician John von Neumann was able to solve this problem instantly in his head. This video teaches a trick so you can solve the puzzle quickly too.

    Blog post:

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    My Books

    The Joy of Game Theory shows how you can use math to out-think your competition. (rated 4/5 stars on 23 reviews)

    The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 5/5 stars on 1 review)

    Math Puzzles Volume 1 features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.5/5 stars on 11 reviews.

    Math Puzzles Volume 2 is a sequel book with more great problems.

    Math Puzzles Volume 3 is the third in the series.

    40 Paradoxes in Logic, Probability, and Game Theory contains thought-provoking and counter-intuitive results. (rated 4.9/5 stars on 7 reviews)

    The Best Mental Math Tricks teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 3 reviews)

    Multiply Numbers By Drawing Lines This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 1 review)

  • Is Most Published Research Wrong?

    12:22

    Mounting evidence suggests a lot of published research is false.
    Check out Audible:
    Support Veritasium on Patreon:

    Patreon supporters:
    Bryan Baker, Donal Botkin, Tony Fadell, Jason Buster, Saeed Alghamdi

    More information on this topic:

    The Preregistration Challenge:

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    Why Most Published Research Findings Are False:


    Trouble at the Lab:


    Science isn't broken:


    Visual effects by Gustavo Rosa

  • The Infinite Pattern That Never Repeats

    21:12

    Simple rules of geometry meant that 5-fold symmetry was impossible as were crystals without a periodic structure. This turns out to be wrong. Thanks to LastPass for sponsoring a portion of this video. Click here to start using LastPass:

    Huge thanks to Prof. Paul Steinhardt for the interview on this topic. Check out his book ‘The Second Kind of Impossible’

    If you'd like to learn more about Penrose tilings, go check out Penrose Tiles to Trapdoor Ciphers by Martin Gardener, which helped my research for this video.

    Filmed by Gene Nagata (Potato Jet on YouTube)
    Animations by Iván Tello and Jonny Hyman
    Editing, Coloring, Music & Audio mastering by Jonny Hyman

    Prague scenes filmed in 2012.
    Special thanks to Raquel Nuno for helping with the tilings!

    Additional Music from Epidemic Sound

  • Australias China Problem

    12:11

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    Animation by Josh Sherrington
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    UNSW photo courtesy Sardaka, University of Sydney photo courtesy Jason Tong

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  • Science from a Sheet of Paper - Tadashi Tokieda

    50:35

    By curling, folding, crumpling, sometimes tearing paper, Tadashi Tokieda will explore a variety of unexpected phenomena - from geometry and the traditional art of origami, to magic tricks and engineering of materials.

  • Exploring The World Of Quantum Physics with Jim Al-Khalili | Spark

    58:50

    Professor Jim Al-Khalili traces the story of arguably the most important, accurate and yet perplexing scientific theory ever: quantum physics.

    The story of quantum physics starts at the beginning of the 20th century with scientists trying to better understand how light bulbs work. This simple question soon led scientists deep into the hidden workings of matter, into the sub-atomic building blocks of the world around us. Here they discovered phenomena unlike any encountered before - a realm where things can be in many places at once, where chance and probability call the shots and where reality appears to only truly exist when we observe it.

    Albert Einstein hated the idea that nature, at its most fundamental level, is governed by chance. Jim reveals how in the 1930's, Einstein thought he'd found a fatal flaw in quantum physics. This was not taken seriously until it was tested in the 1960s. Professor Al-Khalili repeats this critical experiment, posing the question does reality really exist, or do we conjure it into existence by the act of observation?

    Elsewhere, we explore how the most famous law of quantum physics – The Uncertainty Principle – is obeyed by plants and trees as they capture sunlight during the vital process of photosynthesis. Could quantum mechanics explain the greatest mystery in biology - evolution?

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  • Are We Living In A Multiverse?

    26:47

    Catalyst: Custom Universe – Consider one of the most perplexing problems of modern physics and philosophy: is the universe fine-tuned for us?

    Subscribe to Journeyman for daily current affairs and science reports:
    For more journeyman science:

    Einstein predicted them and finally a telescope may have found evidence they exist – gravity waves. And, excitingly, the discovery supports the idea that there may be many universes out there, of which ours is just one. Custom Universe explores the idea that we could be living in a multiverse.

    Catalyst, ABC Australia

    Journeyman Pictures brings you highlights from the cutting-edge science series, ‘Catalyst’, produced by our long-term content partners at ABC Australia. Every day we’ll upload a new episode that takes you to the heart of the most intriguing and relevant science-related stories of the day, transforming your perspective of the issues shaping our world.

  • Principles of Quantum Mechanics

    52:42

    Title: Origins Science Scholars Program Principles of Quantum Mechanics
    Speaker: Harsh Mathur, PhD
    Location: Degrace Hall, Case Western Reserve University, Cleveland, Ohio
    Date: April 5, 2011

  • The Science of Thinking

    12:10

    How the brain works, how we learn, and why we sometimes make stupid mistakes.
    Submit ideas:
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    Thanks to Patreon supporters:
    Nathan Hansen, Donal Botkin, Tony Fadell, Zach Mueller, Ron Neal

    Support Veritasium on Patreon:

    This video was inspired by the book Thinking Fast and Slow by Daniel Kahneman

    Harpist: Lara Somogyi
    Animator: Jesse Agar
    Filmed by Raquel Nuno

    Music by Kevin MacLeod, Sneaky Adventure Harlequin

  • Why and How Consciousness Arises

    57:50

    At our Feb. 5 Grand Rounds, Mark Solms, PhD, of the University of Cape Town, presented on how the metaphysical experience of consciousness relates to the physical brain—and why psychiatrists should care.

  • 4 Revolutionary Riddles

    4:24

    Can you solve these four rotation-related riddles?
    Support Veritasium on Patreon:
    Test yourself playlist:

    Huge thanks to Patreon supporters:
    Jeff Straathof, Zach Mueller, Ron Neal, Nathan Hansen

    I came across these four physics puzzles over the years in discussions with Neil deGrasse Tyson (riddle 4: which part(s) of a moving train are going backwards with respect to the ground?), Simon Pampena (riddle 2: run around a track twice, the first time slowly, the second time much faster so that the average for the two laps is twice the speed of the first lap). Someone tweeted me a video of the mystery cylinder rolling down the ramp in riddle 1 (sorry I'm not sure who it was). Riddle three about a bicycle going forward or backward when it's bottom peddle is pulled back was brought to me by a number of people and I appreciate all of their help!

    Filmed by Raquel Nuno.
    Thanks to everyone at the Palais de la Decouverte! I've had this footage for five years and am only finally releasing it now. I wanted to talk about the way grass grows on a spinning turntable but I couldn't locate the footage...

  • 4 Revolutionary Riddles Resolved!

    8:51

    The solution to 4 rotation-related riddles, including the mystery cylinder, bike pedal pulling puzzle, track problem, and train part going backwards. Thank you to everyone who responded, liked, shared, or made a video response.
    Please fill out this short survey for research:

    Special thanks to:
    Mathematician George Hart:
    For allowing me to use excerpts from his pedal pulling puzzle solution:

    Petr Lebedev for combing through thousands of comments and providing the stats I gave in this video.

    Video responses I used in this video (or watched):
    everWonder?
    A Random Nerdy Channel
    The Physics DoJo
    Oblivious Jim
    Armchair Explorers
    MrEngineeringGuy
    Professor Cubers
    Scoop Science

    A few notes on the puzzle:
    1. A half-full container of honey does pretty well in reproducing the behaviour of the mystery cylinder. I wonder if the motion is a little smoother or more periodic with the ping-pong balls because they move as organized objects - also the delays between motion seemed to be longer with them than without ping pong balls.

    2. For the average speed track problem, every time I said velocity I meant speed. Sorry to the pedants out there who are perhaps looking for some trick answer due to displacement being zero when you run around a track.

    3. Although a lot of people identified it was something about a train's wheels that move backwards, fewer identified that specifically it was the part of the flange below the rail. Some simply said the bottom half of the wheel.

    4. The bicycle question is perhaps the most complex of these riddles. If you tried it with a bike you likely found that it went backwards. But what happens if you sit on the bike and only push backwards on the bottom pedal. The answer might surprise you so give it a shot!

  • Worlds Longest Straw

    7:21

    What is the longest drinking straw that you can actually drink out of? Well in this video, we put the theory to the test. We started off with a one metre long straw made out of drinking straws taped together. We moved on to two pieces of plastic tubing, each 6 metres in length with different diameters. Then we tried a 10.5 metre tube over a cliff's edge. The maximum we achieved was about 7 metres though theoretically up to 10.3 metres is possible if a perfect vacuum is created.

  • Explained: 5 Fun Physics Phenomena

    6:11

    Explanations for
    Follow me on twitter:
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    For more on deflecting polar streams with electric fields, see:



    I'm in Hobart for a live show on Friday at UTAS followed by gigs in Sydney and Canberra next weekend.

  • Pulling obelisks down efficiently – question from Professor Poveys Perplexing Problems

    25:52

    This video explores one of the questions in the book Professor Povey's Perplexing Problems written by Thomas Povey.

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    Contact [mjkim22@pupils.nlcsjeju.kr] to give any suggestions for the channel!

    Enjoy Physics :)

    Bibliography:
    – Povey, T. (2015). Professor Povey's perplexing problems: Pre-university physics and maths puzzles with solutions. London: Oneworld Publications.

  • How physicists solved the problem of infinity

    2:07

    During the mid 20th century, physicists were grappling with a perplexing puzzle. It seemed that every time they applied equations to explain fundamental properties we see and experience around us — like the mass of a particle or what happens when two particles interact with each other — they always got the same answer: infinity.

    But this wasn't a result at all. It was mathematics' way of telling them that they were doing something wrong. Here, professor of physics and mathematics at Columbia University and co-founder of the World Science Festival, Brian Greene, reveals the story of how physicists ultimately tackled the puzzle of infinity.

    You can learn more fascinating science at this year's 10th annual World Science Festival in NYC taking place from May 30-June 4. Following is a transcript of the video:

    Infinity is a way that nature, kind of, grabs you by the lapel and slaps you in the face and says, “You were doing something that doesn’t make any sense.”

    So, one of the big problems that afflicted quantum mechanics is that when scientists started to do calculations with the structure, they found an answer that would pop out of the mathematics and did not make any sense.

    The answer was infinity.

    Almost any question that you asked, if you did the calculations, you know, “How does at a mass of a particle change?”,“How do these two particles slam into each other?”

    The answer was infinite.

    And infinite doesn’t mean big. So people realized that we had to find a way to deal with these infinities. Kind of get rid of them. During, I guess, it was the ’50s and ’60s, a group of scientists came up with a way of thinking about it, to got rid of the infinities.

    And in essence, what they found is we were taking our equations a little too seriously.

    We were pushing our equations to arbitrarily short distances. Arbitrarily high energy, where they, probably, don’t actually apply.

    So what people realized is that if you cut off the equations, be more modest in how you apply them you can naturally get rid of the infinities and, in a way, still have a predictive theory.

    So this is the subject of normalization in quantum field theory and that was a breakthrough that allowed us get things like the Standard Model of particle physics, which predicted the Higgs bosom that was discovered in 2012, by the Large Hadron Collider.

    This is a structure, a mathematical structure that can make predictions for the properties of particles that agrees with observations to ten decimal places.

    So this is, in many ways, the shining wonder of theoretical physics and without normalization, getting rid of the infinities — the structure would not fly.

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  • 3 हैरान करने वाली भौतिकी समस्याएँ | 3 Perplexing Physics Problems

    12:33

    क्यों हिलने के बाद सोडा विस्फोट होता है? क्या बर्फ पहले ताजे या खारे पानी में पिघलती है?

    इस वीडियो में उन प्रयोगों को दिखाया गया है जो वर्षों से विज्ञान शिक्षकों द्वारा मुझे दिखाए गए हैं।बर्फ खारे पानी में जल्दी पिघलती है या ताजे पानी में? - यह प्रयोग मैंने पहली बार, उटाह साइंस टीचर्स कांफ्रेंस में देखा था। एक चेन पर धातु के छल्ले वाला डेमो फ्लोरिडा में हुए एक शिक्षकों के इवेंट से आया है । कार्बोनेटेड पेय को शेक कर के प्रेशर बढ़ाने वाला आईडिया एक ईमेल से मिला था।

  • Professor Poveys Perplexing Problems - Official Video

    3:08

    Thomas Povey, Professor of Engineering Science at the University of Oxford, where he researches jet-engine and rocket technology, on his new book Professor Povey's Perplexing Problems: a delightful and idiosyncratic romp through pre-university maths and physics.

    Find out more about the book here:

  • Stupid Physics Trick #4 - The Bar Trick

    3:39

    Prof. Kathryn Mayer show's us how to suspend a water bottle with just some string and a few matches. See more stupid physics tricks here:

  • The three switches puzzle: Solution

    3:34

    Are you as smart as a Norwegian crime writer? Have you had a lightbulb moment and solved Alex's classic Three Switches puzzle? Here's the solution.

    Click here to go back to the puzzle ►

    Subscribe here ►

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  • Imaginary Numbers

    42:12

    Melvyn Bragg grapples with the concept of imaginary numbers. Perplexing digits that underpin the majority of technology we take for granted today, from radios to computers to MRI scans; not to mention quantum mechanics.

  • Physics is still in crisis

    6:54

    There has been no progress in the foundations of physics for 40 years. In my book Lost in Math I have explained why that is and what can be done about this. In this video, I briefly summarize the content of the book.

    Support me on Patreon:

  • What is the Cosmic Microwave Background Radiation? And what does it mean?

    45:59

    This video provides an overview of the accidental discovery and explanation of the cosmic microwave background radiation, the afterglow of the big bang. After reviewing the initial experimental work of Penzias and Wilson, a detailed account of the theoretical interpretation is presented, including a discussion of the thermodynamic legacy of the big bang, the Planck radiation law, recombination, and galaxy formation.

    References for the video:

    The First Three Minutes - Steven Weinberg
    Cosmology - Steven Weinberg
    The Inflationary Universe - Alan Guth
    Introduction to Cosmology - Matts Roos
    An Introduction to Modern Cosmology - Andrew Liddle
    Introduction to Cosmology - Barbara Ryden

    You can help support this channel via the Physics Explained Patreon account:

    You can follow me on instagram:

    You can follow me on Twitter:

  • Freefall - Physics 101 / AP Physics 1 Review with Dianna Cowern

    22:21

    Lesson 2 of Dianna's Intro Physics Class on Physics Girl. Topic: Freefall. Never taken physics before? Want to learn the basics of physics? Need an AP Physics 1 review before the exam? This course is for you!

    Exercises in this video:

    Problem 1: If we drop a wrecking ball from a height of 35 meters, how long will it take to fall?

    Problem 2: The ball bounces on a trampoline. It takes the ball 1.7 seconds to reach its maximum height. What is the height? How fast was the ball going when it left the trampoline?

    Problem 3: You dive off a diving board, 5 meters high, into a pool. You end up 2.5 meters deep in the pool. Assuming constant acceleration, what was your acceleration while the pool water was you slowing down?


    Dianna Cowern - Executive Producer/Host/Writer
    Jeff Brock - Lead Writer/Course Designer
    Laura Chernikoff - Producer
    Victoria Page - Video Editor
    Sophia Chen - Researcher/Writer
    Levi Butner - Videographer
    Hope Butner - Production Assistant
    Darren Dyk - Slow Motion Cinematography
    Andy Brown - Curriculum Consultant
    Set Design - Lauren Ivy
    Vanessa Hill - Consulting Producer
    Aleeza McCant - Illustrator
    Alicia Cowern - Transcription
    Consultant - Kyle Kitzmiller
    Lucy Brock, Samantha Ward - Curriculum Consultants

  • Is Glass a Liquid?

    7:02

    Stained glass is thicker at the bottom - so is it a liquid? Earth's mantle enables plate tectonics, so is it a liquid?
    Check out Audible:
    Sign up for the mailing list:
    Pitch drop experiment:

    Thanks to Meg Rosenburg for scripting and animation, Raquel Nuno for filming and Aaron White for script consultation.

  • Alan Guth: Inflationary Cosmology: Is Our Universe Part of a Multiverse?

    1:19:54

    Inflationary Cosmology: Is Our Universe Part of a Multiverse?
    Breakthrough Prize in Fundamental Physics Laureate Alan Guth, Hunter College (CUNY), New York, NY, May 13, 2013

  • Simulations of the Glasma in 2+1 and 3+1 D by David Müller

    1:5:30

    DISCUSSION MEETING

    EXTREME NONEQUILIBRIUM QCD (ONLINE)

    ORGANIZERS: Ayan Mukhopadhyay (IIT Madras) and Sayantan Sharma (IMSc Chennai)

    DATE & TIME: 05 October 2020 to 09 October 2020

    VENUE: Online

    Understanding quantum gauge theories is one of the remarkable challenges of the millennium. In particular, the phenomenon of confinement in Quantum Chromodynamics (QCD) is regarded as one of the most fundamental unsolved problems in physics. A fantastic opportunity to combine our theoretical understanding with experiments has emerged from the recent heavy-ion collision experiments at RHIC and CERN, which have reported a plasma of deconfined coloured degrees of freedom called the quark-gluon plasma (QGP). However it is not yet understood how such a near-thermal plasma is formed within a remarkably short time scale under such non-equilibrium conditions. The microscopic processes which lead to thermalisation or rather hydrodynamisation of the QGP and eventually to hadronisation, could hold the key to our understanding of the inner workings of gauge theories. The study of non-equilibrium phenomena in QCD at extreme temperatures and densities along with their perplexing complexities has thus emerged as a nascent area of research, which will oversee many breakthroughs in the coming years. In this workshop, we will review the current state-of-the art theoretical tools of non-equilibrium quantum field theories in general and explore what needs to be done to address some of the open questions in the context of thermalization of the strongly interacting QCD matter.

    Eligibility criteria: Any doctoral/postdoctoral researcher or faculty member from a research institute or university working in the hep-th /hep-lat/hep-ph/nucl-th areas can apply. Preference will be given to those who are working on the fields related to the theme of the conference.

    CONTACT US : program@icts.res.in
    PROGRAM LINK:

    Table of Contents (powered by
    0:00:00 Simulations of the Glasma in 2+1 and 3+1
    0:00:10 Institute for Theoretical Physics TU Wien, Austria
    0:00:33 Overview
    0:01:09 Literature
    0:01:18 Relativistic heavy ion collisions
    0:02:32 State of the art: a chain of simulations
    0:04:45 Color glass condensate
    0:11:45 The Glasma in 2+1D
    0:11:51 General collision scenario
    0:13:09 Ultra-relativistic collision scenario
    0:15:34 The boost-invariant Glasma
    0:17:40 Energy-momentum tensor
    0:21:23 The Glasma in 3+1D
    0:21:28 Relativistic collision scenario with finite widths
    0:24:12 Real-time lattice gauge theory
    0:27:51 Colored particle-in-cell method
    0:31:13 McLerran-Venugopalan model in 3+1D
    0:33:02 Energy-momentum tensor
    0:34:05 Rapidity profiles
    0:35:21 Pressure anisotropy
    0:38:06 Other works on 3+1D Glasma
    0:39:31 Jets in the Glasma
    0:43:29 Jet momentum broadening in the Glasma
    0:45:24 Accumulated momenta at 7 = 0.6 fm/c
    0:46:37 Outlook
    0:46:58 Thank you!
    0:48:05 Rapidity profiles
    0:49:20 Glasma in 3+1D
    0:51:34 Jet momentum broadening in the Glasma
    0:56:39 Extensions

  • Sign of a Function

    8:32

    More resources available at

  • Answer to Veritasium 4 Revolutionary Riddles - Part 1 of 4 - Average Speed

    12:23

    My answer to the 2nd question (average speed) from Veritasium Revolutionary Riddles. Check out parts 2-4 for solutions to the other questions.

    Veritasium original video:

  • Episode 50: Particles And Waves - The Mechanical Universe

    29:03

    Episode 50. Particles and Waves: Evidence that light can sometimes act like a particle leads to quantum mechanics, the new physics.

    “The Mechanical Universe,” is a critically-acclaimed series of 52 thirty-minute videos covering the basic topics of an introductory university physics course.

    Each program in the series opens and closes with Caltech Professor David Goodstein providing philosophical, historical and often humorous insight into the subject at hand while lecturing to his freshman physics class. The series contains hundreds of computer animation segments, created by Dr. James F. Blinn, as the primary tool of instruction. Dynamic location footage and historical re-creations are also used to stress the fact that science is a human endeavor. 

    The series was originally produced as a broadcast telecourse in 1985 by Caltech and Intelecom, Inc. with program funding from the Annenberg/CPB Project.

    The online version of the series is sponsored by the Information Science and Technology initiative at Caltech. 

    ©1985 California Institute of Technology, The Corporation for Community College Television, and The Annenberg/CPB Project

  • TCC Physics Professor Goes Viral

    2:39

    A local physics professor has taken over the internet after a video of his class experiments went viral.

  • Surface topological order - uniting `integer and `fractional.. by Ashvin Vishwanath

    1:10:21

    INFOSYS-ICTS CHANDRASEKHAR LECTURES

    ENTANGLEMENT AND TOPOLOGY IN QUANTUM SOLIDS

    SPEAKER: Ashvin Vishwanath (Harvard University)

    DATE: 23 December 2019, 16:00 to 17:00

    VENUE: Ramanujan lecture hall, ICTS campus

    Lecture 1 : Entanglement and Topology in Quantum Solids.

    Date & Time : Monday, December 23, 2019 at 16:00


    Lecture 2 : Topology, correlations and superconductivity in magic angle graphene.

    Date & Time : Tuesday, December 24, 2019 at 16:00


    Lecture 3 : Surface topological order - uniting `integer' and `fractional' topological states.

    Date & Time : Thursday, December 26, 2019 at 15:00



    Common Abstract : Quantum entanglement is the origin of both the perplexing properties of quantum systems and the power of many proposed quantum technologies. While largely studied in the the context of a few particles, recent work has emphasized its importance in macroscopic systems, such as solids with many interacting electrons. I will discuss examples where quantum entanglement has helped us classify and discover new topological phases of matter, which may have applications to future quantum technologies. Finally, I will review related theoretical progress on a remarkable new quantum system - two sheets of graphene, rotated relative to one another by just one degree - where a variety of states including superconductivity have been observed.



    This lecture series is part of the program Novel phases of quantum matter.

    Table of Contents (powered by
    0:00:00 Surface topological order - uniting 'integer' and `fractional' topological states (Lecture - 03)
    0:00:14 Topology, correlations and superconductivity in magic angle graphene II
    0:00:45 Interaction Effects in Pristine Magic Angle Graphene
    0:01:57 Two Paradigms for Correlated Electrons
    0:05:46 Magic Angle Twisted Bilayer Graphene
    0:06:19 Brief Review of Experiment
    0:07:58 Including Interactions
    0:13:58 Simplified Model: Chiral Model, Flat Band, Spineless
    0:16:55 Inter Valley Coherence
    0:19:34 Energetics
    0:24:34 Ground State of Chiral Model- Generalized Ferromagnet
    0:29:01 Including Interactions
    0:30:22 Breaking the Degeneracy
    0:35:29 Hartree Fock Numerics
    0:38:06 Quantum Phase Transition
    0:40:12 Kramer's IVC - Properties
    0:43:57 Ground State - Kramer's IVC
    0:48:16 Kramer's IVC & Superconductivity
    0:50:39 Reintroducing Spin
    0:52:42 Conclusions
    0:54:41 Q&A
    1:01:03 Surface Topological order in an Exactly Soluble Model
    1:03:56 Q&A

  • Ankit Patel: Breaking Bad: Recent Advances from Function Space Characterization of Neural Nets ...

    58:05

    Machine Learning for Physics and the Physics of Learning 2019
    Workshop I: From Passive to Active: Generative and Reinforcement Learning with Physics

    Breaking Bad: Recent Advances from Function Space Characterization of Neural Nets with Implications for Physical Applications
    Ankit Patel, Rice University

    Abstract: How does a neural network approximate a given function? What kinds of functions can it approximate well/poorly? How does the optimization algorithm bias learning? Deep Learning has revolutionized many fields, and yet answers to fundamental questions like these remain elusive. This lack of understanding makes it difficult to develop applications in fields like physics where substantial prior knowledge exists.

    Here we present a new emerging viewpoint -- the functional or spline perspective -- that has the power to answer these questions. We will review the latest results from this work and talk about our most recent advances. We find that understanding NNs is most easily done in the function space, not in the parameter space. This change of coordinates sheds light on many perplexing phenomena including the overparametrization, “unreasonable” generalization, the loss surface and the consequent difficulty of training, and the implicit regularization of gradient descent. We present several novel results concerning how (deep) ReLu nets approximate functions, the number of bad local minima in the loss surface, and the fundamental dynamical laws governing breakpoints and slopes during gradient descent.

    The impact on physical applications will be made by showing how the breakpoint densities of randomly initialized NNs poorly model boundary conditions in physical applications such as approximating the energy function of a protein molecule (joint work with Cecilia Clementi, Rice BioPhysics). Another application will show how to impose global group symmetries on the learned function (joint work with Fabio Anselmi, IIT).

    Institute for Pure and Applied Mathematics, UCLA
    September 26, 2019

    For more information:

  • Physics students react to 1888 exam

    6:50

    1888 University of Sydney exams (physics on page 367):

    People featured in this video:
    Isabel Bunting (@isabel_bunting)
    Zachary Picker
    Daniel Collison
    Aesha Bhansali (@aeshaBhansali)
    Petr Lebedev (@SciencePetr)
    Jules Rankin (@jules_rankin)

    A video on Petr's channel:

    Thanks to Karin from the University of Sydney Archives for helping me to find the exams.

    ???? Your invitation to subscribe to my channel:

    ????Support me on Patreon:

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