Negative Pressure Exists! http://bit.ly/TFilQ8
Vsauce's Space Straw: http://bit.ly/XubIm3
Smarter Every Day's Prince Rupert's Drop: http://bit.ly/10VQBGW
ViHart's Optimal Potatoes: http://bit.ly/14egJoe

Thanks to Questacon for filming! Check out their slow-mo playlist: http://bit.ly/ZoWFGR
Science Alert brings science to your news feed: http://on.fb.me/14ehuxA

Music by Kevin Mcleod (http://incompetech.com): Pale Rider & The Cannery

One scientist caused two environmental disasters and the deaths of millions. A part of this video is sponsored by Wren. Offset your carbon footprint on Wren: ​https://www.wren.co/start/veritasium. For the first 100 people who sign up, I will personally pay for the first month of your subscription!

Special thanks to our Patreon supporters! Join the community to help us keep our videos free, forever:
https://ve42.co/PatreonDEB

Massive thanks to Prof. Francois Tissot for suggesting we make a video on the topic of isotope geochemistry. Huge thanks to Prof. Bruce Lanphear for consulting with us on lead and cardiovascular diseases. Thanks to Rayner Moss for the help with the fire-piston.

Patterson’s 1995 interview audio courtesy of the Archives, California Institute of Technology.

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Other great resources you should check out:
Bill Bryson has a chapter in his fantastic “A Short History of Nearly Everything”
Radiolab have a wonderful podcast: https://www.wnycstudios.org/podcasts/...
Cosmos: A Spacetime Odyssey has a wonderful episode – S1E7 which does a great job of telling the story of Clair Patterson
A fantastic Mental floss article – https://www.mentalfloss.com/article/9...

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References:

Much of the lead-crime hypothesis data is from Rick Nevin’s work – https://ricknevin.com/

WHO factsheet on lead poisoning – https://www.who.int/news-room/fact-sh...

WHO press release about the end of leaded gasoline https://news.un.org/en/story/2021/08/...

UNICEF report – https://ve42.co/UNICEF

Needleman, H. (2004). Lead poisoning. Annu. Rev. Med., 55, 209-222. https://ve42.co/Needleman1

Needleman, H. L. (1991). Human lead exposure. CRC Press. https://ve42.co/Needleman2

Needleman, H. L. et al. (1979). Deficits in psychologic and classroom performance of children with elevated dentine lead levels. New England journal of medicine, 300(13), 689-695. – https://ve42.co/Needleman3

Needleman, H. L. et al. (1996). Bone lead levels and delinquent behavior. Jama, 275(5), 363-369. https://ve42.co/Needleman4

Kovarik, W. J. (1993). The ethyl controversy: the news media and the public health debate over leaded gasoline, 1924-1926 https://ve42.co/Kovarik2

Edelmann, F. T. (2016). The life and legacy of Thomas Midgley Jr. In Papers and Proceedings of the Royal Society of Tasmania https://ve42.co/Edelmann

More, A. F. et al. (2017). Next‐generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: Insights from the Black Death. GeoHealth, 1(4), 211-219. https://ve42.co/More1

McFarland, M. J., et al. (2022). PNAS 119(11), e2118631119. https://ve42.co/McFarland

Kovarik, W. (2005). Ethyl-leaded gasoline. International Journal of Occupational and Environmental Health, 11(4), 384-397. https://ve42.co/Kovarik3

Nevin, R. (2007). Understanding international crime trends: the legacy of preschool lead exposure. Environmental research, 104(3), 315-336. – https://ve42.co/Nevin2007

Ericson, J. E., et al. (1979). Skeletal concentrations of lead in ancient Peruvians. New England Journal of Medicine, 300(17), 946-951. – https://ve42.co/Ericson1

Patterson, Claire. The Isotopic Composition of Trace Quantities of Lead and Calcium https://ve42.co/Patterson1

Boutron, C. F., & Patterson, C. C. (1986). Lead concentration changes in Antarctic ice during the Wisconsin/Holocene transition. Nature, 323(6085), 222-225. – https://ve42.co/Boulton1

Patterson, C. (1956). Age of meteorites and the earth. Geochimica et Cosmochimica Acta, 10(4), 230-237. – https://ve42.co/Patterson2

Lanphear, B. P. et al (2018). Low-level lead exposure and mortality in US adults: a population-based cohort study. The Lancet Public Health, 3(4), e177-e184. – https://ve42.co/Lanphear1

Schaule, B. K., & Patterson, C. C. (1981). Lead concentrations in the northeast Pacific: evidence for global anthropogenic perturbations. Earth and Planetary Science Letters, 54(1), 97-116. – https://ve42.co/Schaule1

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Special thanks to Patreon supporters: Inconcision, Kelly Snook, TTST, Ross McCawley, Balkrishna Heroor, Chris LaClair, Avi Yashchin, John H. Austin, Jr., OnlineBookClub.org, Dmitry Kuzmichev, Matthew Gonzalez, Eric Sexton, john kiehl, Anton Ragin, Diffbot, Micah Mangione, MJP, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Dumky, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Mac Malkawi, Michael Schneider, jim buckmaster, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Stephen Wilcox, Marinus Kuivenhoven, Clayton Greenwell, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

▀▀▀
Written by Derek Muller, Petr Lebedev, Chris Stewart, and Katie Barnshaw
Edited by Trenton Oliver
Filmed by Petr Lebedev
Animation by Fabio Albertelli, Jakub Misiek, Ivy Tello, Mike Radjabov, and Caleb Worcester
SFX by Shaun Clifford
Additional video/photos supplied by Getty Images
Music from Epidemic Sound
Produced by Derek Muller, Petr Lebedev, and Emily Zhang

How does Japan prepare for its devastating earthquakes? With this giant simulator. For a free trial to Shopify go to https://www.shopify.com/veritasium.

If you’re looking for a molecular modeling kit, head to https://ve42.co/SnatomsV to try Snatoms – a kit I invented where the atoms snap together magnetically.

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A massive thank you to everyone at NIED for allowing access to their facility. Massive thanks to Okouchi-san for arranging this shoot.

A huge thank you to Dr. Yohsuke Kawamata for the tour of E-defense and for sharing his deep expertise.

▀▀▀
References:
Nakashima, M., et al. (2018). Experiences, accomplishments, lessons, and challenges of E‐defense. Tests using world's largest shaking table. Japan Architectural Review, 1(1), 4-17. - https://ve42.co/Nakashima
Suganuma, K. (2005). 3-D Full-Scale Earthquake Testing Facility (E-Defense). NISTEP Science & Technology Foresight Center. - https://ve42.co/Suganuma
Ohtani, K., et al. (2004). Construction of E-Defense (3-D full-scale earthquake testing facility). In Thirteenth World Conference on Earthquake Engineering (Vol. 189). - https://ve42.co/Ohtani
Horiuchi, T., et al. (2022). Contributions of E-Defense Shaking Table to Earthquake Engineering and its Future. Journal of Disaster Research, 17(6), 985-999. - https://ve42.co/Horiuchi
Nakamura, I., et al. (2008). E-Defense experiments on full-scale wooden houses. In Proceedings of the 14th World conference on earthquake engineering, Beijing, China (pp. 12-17). - https://ve42.co/Nakamura
Japan: The Next Big Quake. Financial Times. - https://ve42.co/BigQuake


Images & Video:
Kobe earthquake compilation - https://ve42.co/Kobe


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Special thanks to our Patreon supporters:
carrotcypher, Chris Harper, Max Paladino, Balkrishna Heroor, Adam Foreman, Orlando Bassotto, Tj Steyn, meg noah, KeyWestr, TTST, John H. Austin, Jr., john kiehl, Anton Ragin, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Juan Benet, David Johnston, Ubiquity Ventures, Richard Sundvall, Lee Redden, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Sam Lutfi.

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Directed by Will Wood and Petr Lebedev
Written by Will Wood, Petr Lebedev and Derek Muller
Edited by Jack Saxon and Trenton Oliver
Animated by Fabio Albertelli, Ivy Tello, Leigh Williamson, David Szakaly
Filmed by Petr Lebedev, Lui Kimishima and Derek Muller
Produced by Will Wood, Petr Lebedev, Han Evans and Derek Muller
Thumbnail by Ren Hurley

Additional video/photos supplied by Getty Images and NIED (E-defense)
Music from Epidemic Sound

How Thermite turned the clickety-clack of railroads into seamless, silent tracks. Get an exclusive 15% discount on Saily data plans! Use code veritasium at checkout. Download Saily app or go to https://saily.com/veritasium
A massive thank you to everyone at Goldschmidt for making this possible. With special thanks to Dr. Axel Hoeschen, Christof Gassmann and Claudia Koch.

If you want to learn all the details about why we don’t need expansion joints anymore, check out Grady’s excellent video here: youtu.be/zqmOSMAtadc

If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically. https://snatoms.com/

Sign up to the Veritasium newsletter for weekly science updates - https://ve42.co/Newsletter

▀▀▀
00:00 The problem with continuous welded rail
03:33 How to weld two rails together
10:16 Why is rapidly cooled steel brittle?
11:40 Thermite reaction and a see-through mould
16:30 Clean up
19:11 Metallurgy
22:15 How strong is the weld?
24:26 Why don’t the rails buckle?

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References:
Practical Engineering. Why Railroads Don't Need Expansion Joints youtu.be/zqmOSMAtadc
Stress–strain curve In Wikipedia - https://ve42.co/stressstrain
The Efficient Engineer. Understanding Metals via Youtube https://youtu.be/PaGJwOPg2kU
moodlemech. Properties and Grain Structure via Youtube - youtu.be/uG35D_euM-0

Images & Video:
bhadeshi123. Martensitic transformation via Youtube youtu.be/OQ5lVjYssko
Stratford Works In Wikipedia - https://ve42.co/stratford
Electric Tram 1881 In Wikipedia - https://ve42.co/tram
Water Quenched Steel In Wikipedia - https://ve42.co/quench
Synagoge 1922 In Wikipedia - https://ve42.co/synagoge

▀▀▀
Special thanks to our Patreon supporters!
Join the community to help us keep our videos free, forever: https://ve42.co/PatreonDE

Alexander Tamas, Autodidactic Studios, Farbod Mansorian, Gnare, Juan Benet, Lee Redden, Meekay, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Ubiquity Ventures, Adam Foreman, Albert Wenger, Anton Ragin, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, Evgeny Skvortsov, Garrett Mueller, gpoly, Greg Scopel, I. H., KeyWestr, Kyi, Marinus Kuivenhoven, Matthias Wrobel, meg noah, Michael Krugman, Spilmann Reed, Tj Steyn, TTST, wolfee.

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Directed by Derek Muller and Casper Mebius
Written by Derek Muller and Casper Mebius
Edited by Trenton Oliver
Animated by Mike Radjabov, Rokas Vikšraitis and Fabio Albertelli
Filmed by Derek Muller, David Bochmann, Casper Mebius, Luise Dietert, Henning Fischer and Harald Schweiger
Additional research by Geeta Thakur
Produced by Derek Muller, Casper Mebius, Gregor Čavlović, Geeta Thakur, Rob Beasley Spence, Emily Lazard and Tori Brittain
Thumbnail contributions by Peter Sheppard and Ren Hurley
Additional video/photos supplied by Getty Images and Story Blocks
Music from Epidemic Sound

The Event Horizon Telescope Collaboration observed the supermassive black hole at the center of M87, finding the dark central shadow in accordance with General Relativity, further demonstrating the power of this 100 year-old theory.

To understand more about why the shadows look the way they do, check out: https://www.youtube.com/watch?v=zUyH3XhpLTo

I will continue updating this description with more links.

Event Horizon Telescope collaboration: https://ve42.co/EHT

Animations and simulations with English text:
L. R. Weih & L. Rezzolla (Goethe University Frankfurt)
https://youtu.be/jvftAadCFRI

Video of observation of M87 courtesy of:
C. M. Fromm, Y. Mizuno & L. Rezzolla (Goethe University Frankfurt)
https://youtu.be/meOKmzhTcIY

Video of observation of SgrA* courtesy of
C. M. Fromm, Y. Mizuno & L. Rezzolla (Goethe University Frankfurt)
Z. Younsi (University College London)
https://youtu.be/VnsZj9RvhFU

Video of telescopes in the array 2017:
C. M. Fromm & L. Rezzolla (Goethe University Frankfurt)
https://youtu.be/Ame7fzBuFnk

Animations and simulations (no text):
L. R. Weih & L. Rezzolla (Goethe University Frankfurt)
https://youtu.be/XmvpKFSvB7A

Special thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Ron Neal, Stan Presolski, Terrance Shepherd, Penward Rhyme

Scale animation by Maria Raykova

The US Navy has an indoor ocean that can simulate any wave in the world. This video is sponsored by Brilliant. You can get started for free, or the first 200 people to sign up via https://brilliant.org/veritasium get 20% off a yearly subscription.

Special thanks to our Patreon supporters! Join the community to help us keep our videos free, forever:
https://ve42.co/PatreonDEB

▀▀▀
Thanks to Kelley Stirling and the Naval Surface Warfare Center, Carderock Division for the visit.
Thanks to Miguel Quintero and Capt. Todd E. Hutchison for talking to us about the important work going on in the Maneuvering and Seakeeping Basin.
Thanks to Dr. Georgy Manucharyan at the University of Washington for his help in understanding ocean waves.

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References:

Webb, P. (2017). Introduction to Oceanography. Chapter 10: Waves. Online OER textbook. – https://ve42.co/Webb2017
Stewart, R. (2008). Introduction to Physical Oceanography. – https://ve42.co/Stewart2008
van den Bremer, T. S. & Breivik, Ø. (2018). Stokes drift. Phil. Trans. R. Soc. A. – https://ve42.co/Bremer2017
Monismith, S. (2020). Stokes drift: Theory and experiments. Journal of Fluid Mechanics, 884, F1. – https://ve42.co/Monismith2020
Young, I. R. (1999). Wind Generated Ocean Waves. Elsevier. p. 83. – https://ve42.co/Young1999
Wright, P. Island Physics. 4.2 Formation of Waves – https://ve42.co/IslandPhysics
American Bureau of Shipping. (2016). Guidance Notes on Selecting Design Wave by Long Term Stochastic Method. – https://ve42.co/ABS2016
James, S. & Stull, R. (2019). Wave Characteristics. UBC ATSC 113 - Weather for Sailing, Flying & Snow Sports. – https://ve42.co/James2019
Garrison, T. (2009). Oceanography: An Invitation to Marine Science (7th ed). – https://ve42.co/Garrison2009

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Special thanks to our Patreon supporters:
James Sanger, Louis Lebbos, Elliot Miller, Brian Busbee, Jerome Barakos M.D., Amadeo Bee, TTST, Balkrishna Heroor, Chris LaClair, John H. Austin Jr., OnlineBookClub.org, Matthew Gonzalez, Eric Sexton, John Kiehl, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Mac Malkawi, Mike Schneider, John Bauer, Jim Buckmaster, Juan Benet, Sunil Nagaraj, Richard Sundvall, Lee Redden, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi

▀▀▀
Written by Derek Muller & Emily Zhang
Edited by Fabio Albertelli
Animation by Ivy Tello & Mike Radjabov
Filmed by Derek Muller & Emily Zhang
Additional video/photos supplied by Pond5 & Getty Images
Music from Epidemic Sound
Produced by Derek Muller, Petr Lebedev, and Emily Zhang

The title and thumbnail play a huge role in a video's success or failure.
Check out http://kiwico.com/Veritasium50 for 50% off your first month of any subscription!

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Special thanks to Patreon supporters: Alvaro Naranjo, Burt Humburg, Blake Byers, Dumky, Mike Tung, Evgeny Skvortsov, Meekay, Ismail Öncü Usta, 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

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Written by Derek Muller
Animation by Ivy Tello
Filmed by Derek Muller and Emily Zhang
Additional video supplied by Getty Images
Produced by Derek Muller, Emily Zhang and Petr Lebedev

If you spin a raw egg and then stop it, it will start spinning again without you having to touch it. A boiled egg, on the other hand, stops and stays stopped. Why is this? Well a raw egg contains a yolk that moves inside the egg independently of the shell. If you stop the shell, the yolk inside continues to move due to its inertia and it therefore gets the egg spinning again.

I always wanted to know why film looked better than video. Moving electronic images have as long a history but were invented for a different purpose. This video was sponsored by B&H Photo: https://www.bhphotovideo.com

Huge thanks to:

Richard Diehl, Video Labguy https://www.youtube.com/user/videolabguy
https://www.labguysworld.com

Branch Education for awesome animations
https://ve42.co/BranchEd

Minutephysics for mechanical TV animations
https://www.youtube.com/minutephysics

Mark Schubin
Engineer and explainer, SMPTE Life Fellow
https://www.smpte.org

This is a video I've long wanted to make, about what makes video look like video and, up until 10 years ago or so, not as appealing as film. I grew up with the two technologies (film and video) in parallel and to me they always seemed like two ways of achieving the same ends: recording and replaying moving images. But their histories are quite distinct. Film was always a way to capture moving images for later replaying. Video started out as a way to transfer images from one place to another instantaneously. This dates back to the first fax machine, mechanical TV, live broadcast tv and ultimately videotapes. This history focuses on the early decades of video and not the more recent switches to chip cameras and solid state storage. Maybe that's a story for another day.

Additional resources and references:

The Dawn of Tape: Transmission Device as Preservation Medium
https://ve42.co/dawnoftape

What Sparked Video Research in 1877? The Overlooked Role of the Siemens Artificial Eye
https://ve42.co/sparkvideo

Video Preservation Website:
http://videopreservation.conservation-us.org

Image Orthicon Tube:
http://interiorcommunicationse....lectrician.tpub.com/

Film vs Digital
https://stephenfollows.com/film-vs-digital/

Eyes of a Generation:
http://eyesofageneration.com

Television in the US:
http://www3.northern.edu/wild/th100/tv.htm

http://www.classictvinfo.com

Music from https://www.epidemicsound.com "Seaweed" "Capture a Picture 1" "Colorful Animation 4"

The biggest chemical cover up in history. PFAS has polluted the entire global water system. Now, potentially dangerous forever chemicals are being found in the entire US population. Go to https://groundnews.com/Ve to get all sides of every story. Subscribe to save 40% off the unlimited Vantage Plan through our link.

If you’re looking for a molecular modelling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV

Sign up to the Veritasium newsletter for weekly science updates - https://ve42.co/Newsletter

▀▀▀
0:00 Killed by Fridges
5:27 Teflon and The Manhattan Project
7:59 Teflon is Tricky
11:37 The Teflon Revolution
13:27 Earl Tennant's Farm
17:34 Inside DuPont
20:28 Fluoride In Drinking Water
25:00 It's bigger than that
29:23 What is PFAS?
35:56 How much PFAS is in Derek’s blood?
37:56 How forever chemicals get into your blood
46:18 Removing PFAS from drinking water
49:30 Can you lower your PFAS levels?

▀▀▀
A huge thank you to Rob Bilott for his time and expertise. Check out his fantastic book: Bilott, R. (2019). Exposure. Simon and Schuster - https://ve42.co/7R

Rob's story also inspired the 2019 film: Dark Waters.

Thank you to Doctor Mike for giving us a medical perspective on PFAS! Check him out at @DoctorMike

Thank you to Henrik Haggeman and the Puraffinity team, as well as Andrew Patterson and Eurofins, for doing the PFAS testing.

Thank you to Leslie Hamilton, Johns Hopkins APL, Alex Conrad, Imperial College London, Jana Avgustini, and Matija Krvavica for their help on the project.

▀▀▀
PFAS Tools:
PFAS Blood Test - https://ve42.co/PFASTest
What's My Exposure? via www-pfas.pfas-exchange.org - https://ve42.co/myexposure
Serum PFAS Calculator via ics.uci.edu - https://ve42.co/pfascalculator
Interactive Map: PFAS Contamination Crisis via www.ewg.org - https://ve42.co/pfasmapinteractive
The Map of Forever Pollution via foreverpollution.eu - https://ve42.co/foreverpollutionmap
Australian PFAS Chemicals Map via pfas.australianmap.net - https://ve42.co/australianpfasmap

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References:

References can be found here - https://ve42.co/PFASReferences

Images & Video:

Image and video references can be found here - https://ve42.co/PFASVisuals

3D Models:

"Low Poly Base Mesh-530 Tri" (https://skfb.ly/onsxE) by Huge_Man
"Blood Vessel" (https://skfb.ly/owHJX) by IMU University
“Generic Factory” (https://skfb.ly/onQpR) by assetfactory
"Lowpoly People + Waldo" (https://skfb.ly/6zqCE) by Loïc Norgeot
PFOA Molecule via PubChem - https://pubchem.ncbi.nlm.nih.g....ov/compound/Perfluor

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Special thanks to our Patreon supporters:
Adam Foreman, Albert Wenger, Alex Porter, Alexander Tamas, Anton Ragin, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, David Tseng, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, iRick, Jon Jamison, Juan Benet, Keith England, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Samuel White, TTST, Tj Steyn, Ubiquity Ventures, wolfee

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Writers: Gregor Čavlović & Derek Muller
Producer & Director: Gregor Čavlović
Editors: Peter Nelson & Jack Saxon
Camera Operators: Tas Underwood, Emilia Gyles, Gregor Čavlović & Derek Muller
Animators: Andrew Neet, Emma Wright & Fabio Albertelli
Illustrators: Caine Esperanza, Jakub Misiek & Maria Gusakovich
Assistant Editor: James Stuart
Additional Editor: James Horsley
Researchers: Geeta Thakur, Darius Garewal, Gabe Strong & Emilia Gyles
Thumbnail Designers: Ren Hurley & Ben Powell
Production Team: Rob Beasley Spence, Tori Brittain, Casper Mebius, Sulli Yost & Matthew Cavanagh
Executive Producers: Derek Muller & Zoe Heron

Additional video/photos supplied by Getty Images, Pond5.
Music from Epidemic Sound

The logistic map connects fluid convection, neuron firing, the Mandelbrot set and so much more. Fasthosts Techie Test competition is now closed! Learn more about Fasthosts here: https://www.fasthosts.co.uk/veritasium Code for interactives is available below...

Animations, coding, interactives in this video by Jonny Hyman 🙌
Try the code yourself: https://github.com/jonnyhyman/Chaos

References:
James Gleick, Chaos
Steven Strogatz, Nonlinear Dynamics and Chaos

May, R. Simple mathematical models with very complicated dynamics. Nature 261, 459–467 (1976). https://doi.org/10.1038/261459a0

Robert Shaw, The Dripping Faucet as a Model Chaotic System
https://archive.org/details/Sh....awRobertDrippingFauc

Crevier DW, Meister M. Synchronous period-doubling in flicker vision of salamander and man.
J Neurophysiol. 1998 Apr;79(4):1869-78.

Bing Jia, Huaguang Gu, Li Li, Xiaoyan Zhao. Dynamics of period-doubling bifurcation to chaos in the spontaneous neural firing patterns Cogn Neurodyn (2012) 6:89–106 DOI 10.1007/s11571-011-9184-7

A Garfinkel, ML Spano, WL Ditto, JN Weiss. Controlling cardiac chaos
Science 28 Aug 1992: Vol. 257, Issue 5074, pp. 1230-1235 DOI: 10.1126/science.1519060

R. M. May, D. M. G. Wishart, J. Bray and R. L. Smith Chaos and the Dynamics of Biological Populations
Source: Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 413, No. 1844, Dynamical Chaos (Sep. 8, 1987), pp. 27-44

Chialvo, D., Gilmour Jr, R. & Jalife, J. Low dimensional chaos in cardiac tissue. Nature 343, 653–657 (1990). https://doi.org/10.1038/343653a0

Xujun Ye, Kenshi Sakai. A new modified resource budget model for nonlinear dynamics in citrus production. Chaos, Solitons and Fractals 87 (2016) 51–60

Libchaber, A. & Laroche, C. & Fauve, Stephan. (1982). Period doubling cascade in mercury, a quantitative measurement. http://dx.doi.org/10.1051/jphy....slet:019820043070211 43. 10.1051/jphyslet:01982004307021100.

Special thanks to Patreon Supporters:
Alfred Wallace, Arjun Chakroborty, Bryan Baker, DALE HORNE, Donal Botkin, halyoav, James Knight, Jasper Xin, Joar Wandborg, Lee Redden, Lyvann Ferrusca, Michael Krugman, Pindex, Ron Neal, Sam Lutfi, Tige Thorman, Vincent

Special thanks to:
Henry Reich for feedback on earlier versions of this video
Raquel Nuno for enduring many earlier iterations (including parts she filmed that were replaced)
Dianna Cowern for title suggestions and saying earlier versions weren't good
Heather Zinn Brooks for feedback on an earlier version.


Music from:
https://epidemicsound.com "What We Discovered" "A Sound Foundation 1" "Seaweed" "Colored Spirals 4"

https://ve42.co/Artlist "Busy World" "Children of Mystery"

Can you trust your phone? Head to https://brilliant.org/veritasium to start your free 30-day trial and get 20% off an annual premium subscription.

A huge thank you to Linus Sebastian and the team at Linus Tech Tips - check them out at @LinusTechTips

A massive thank you to Alexandre De Oliveira and Karsten Nohl (aka @hackingmatters) for making this demo possible. Karsten has made a great follow-up video on the subject, which you can watch here: https://www.youtube.com/watch?v=miXRoy-5LLo

A special thanks to Crofton Black at Lighthouse Reports, Cathal Mc Daid at Enea, and James Hobson at @hacksmith

00:00 I hacked Linus!
00:59 How Steve Jobs and Steve Wozniak hacked the telephone network
02:22 Early history of the telephone
07:08 The kidnapping of Sheikha Latifa
08:41 How Signalling System No. 7 works
11:03 Why SS7 is vulnerable to hacking
12:15 How hackers gain access to phones
16:17 How I was able to spy on Linus’ phone
18:09 How hackers can intercept text messages
21:04 How your location can be tracked via SS7
29:03 How to protect your phone from hacking

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Special thanks to our Patreon supporters! Join the community to help us keep our videos free, forever: https://ve42.co/PatreonDE

Adam Foreman, Albert Wenger, Anton Ragin, Balkrishna Heroor, Bertrand Serlet, Bill Linder, Blake Byers, Bruce, Burt Humburg, Dave Kircher, David Johnston, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, I. H., Jack Cuprill, John H. Austin, Jr., john kiehl, Juan Benet, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Tj Steyn, TTST, Ubiquity Ventures and wolfee

If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV

▀▀▀
References:
Black, C. (2020). Spy companies using Channel Islands to track phones around the world. The Bureau of Investigative Journalism - https://ve42.co/SpyTBIJ
It is dangerously easy to hack the world’s phones via The Economist - https://ve42.co/EconHack
Blake, H. (2023). The Fugitive Princesses of Dubai. The New Yorker - https://ve42.co/DubaiNY
McDaid, C. (2021). How Surveillance Companies Track You Using Mobile Networks. media.ccc.de - https://ve42.co/McDaid2021
Engel, T. (2014). SS7: Locate. Track. Manipulate. media.ccc.de - https://ve42.co/Engel2014
Nohl, K. (2014). Mobile self-defense. media.ccc.de - https://ve42.co/Nohl2014
How Cell Service Actually Works via WendoverProductions - https://ve42.co/CellWendover
How Telephone Phreaking Worked via The 8-Bit Guy - https://ve42.co/8BitGuy
Transmission Lines: Part 1 An Introduction via TheSiGuy - https://ve42.co/TheSiGuy
The Step-By-Step Switch via AT&T Tech Channel - https://ve42.co/SwitchATNT
Hacking Your Phone via 60 Minutes - https://ve42.co/60minHack
Rosenbaum, R. (1971). Secrets of the Little Blue Box. The Esquire Magazine - https://ve42.co/Rosenbaum1971
Black, C. et. al. (2023). Ghost in the network. Lighthouse Reports - https://ve42.co/Black2023
Kerr, D. (2019). The step-by-step telephone switching system. dougkerr.net - https://ve42.co/Kerr2019
Ecall and 2G/3G Network Obsolescence via PFA Plateforme Automobile - https://ve42.co/PFAAuto2021


Images & Video:
All references can be found here: https://ve42.co/PhoneSpyingImageVideo

▀▀▀
Directed by Henry van Dyck
Written by Henry van Dyck
Edited by Laura Mills
Animated by Fabio Albertelli, Ivy Tello, David Szakaly, and Jakub Misiek
Filmed by Derek Muller and Linus Media Group Team
Additional research by Gabe Strong
Produced by Derek Muller, Henry van Dyck, Rob Beasley Spence, Tori Brittain, Emily Lazard, Luke Lewis, Gregor Čavlović, and Emily Zhang
Thumbnail contributions by Ren Hurley and Peter Sheppard

Additional video/photos supplied by Getty Images and Storyblocks
Music from Epidemic Sound

What was the procedure to launch a nuclear missile?
Uranium premieres: July 28 & 29 on PBS at 10pm ET/ 9pm Central
France and Germany: July 31 at 10pm on ZDF/arte
Norway: August 5 & 6 at 21:30 on NRK2
Australia: August 9, 16, 23 at 8:30pm on SBS
Sweden: TBD
Middle East: TBD

For more information on other screenings go to
https://www.facebook.com/uraniumtwistingthedragon
www.genepoolproductions.com

A big thank you to The Titan Missile Museum, Yvonne and Chuck.
http://www.titanmissilemuseum.org/

Space footage courtesy of NASA

A recent survey of scientific literacy in Australia found 30% believe it takes one day for the Earth to go around the sun. This video provides qualitative evidence for the finding from Sydney's Eastern beaches.

An engineer came up with a plan to drop tungsten telephone poles from space - the idea has been seriously considered on multiple occasions, so we tested it. Head to https://brilliant.org/Veritasium to start your free trial. The first 200 will get 20% off Brilliant's annual premium subscription.

Special thanks to our Patreon supporters! Join the community to help us keep our videos free, forever:
https://ve42.co/PatreonDEB

Massive thanks to Archisand for building such a beautiful sandcastle. https://www.youtube.com/@GregLeBon

Huge thanks to John and Angie Miller for helping us with securing the shooting location and going above and beyond to make this shoot happen – http://highdesertlocations.com/

Thanks to Inland Empire Film Services and the San Bernardino County Film Office for portions of the video shot in the County of San Bernardino.

Massive thanks to Dr David Wright for the interview and providing invaluable guidance during the research for this video.

Here’s a great video about space-based missile defense – https://www.ucsusa.org/resourc....es/space-based-missi

Massive thanks to Adam Savage for being part of this video.

Additional photos from NASA and ESA.

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References:
USAF. (2003). The US Air Force transformation flight plan.

Preston, R., Johnson, D. J., Edwards, S. J., Miller, M. D., & Shipbaugh, C. (2002). Space weapons earth wars. Rand Corporation.

Wright, D., Grego, L., & Gronlund, L. (2005). The physics of space security. A Reference Manual, Cambridge.

DeBlois, B. M., Garwin, R. L., Kemp, R. S., & Marwell, J. C. (2004). Space weapons: crossing the US Rubicon. International Security, 50-84.

Baucom, D. R. (2017). The Rise and Fall of Brilliant Pebbles 1. In United States Military History 1865 to the Present Day (pp. 329-376). Routledge.

Hitchens, T., & Samson, V. (2004). Space-based interceptors: still not a good idea. Georgetown journal of international affairs, 21-29.

National Research Council. (2012). Making sense of ballistic missile defense: An assessment of concepts and systems for US boost-phase missile defense in comparison to other alternatives. National Academies Press.

Borger, J. (2005). Bush likely to back weapons in space. The Guardian, 19.

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Special thanks to: Bernard McGee, James Sanger, Elliot Miller, Brian Busbee, Jerome Barakos M.D., Amadeo Bee, TTST, Balkrishna Heroor, Chris LaClair, John H. Austin Jr., OnlineBookClub.org, Eric Sexton, John Kiehl, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Mac Malkawi, Mike Schneider, John Bauer, Jim Buckmaster, Juan Benet, Sunil Nagaraj, Richard Sundvall, Lee Redden, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi

▀▀▀
Written by Petr Lebedev, Derek Muller, and Emily Zhang
Filmed by Trenton Oliver, Derek Muller, Petr Lebedev, Emily Zhang, Raquel Nuno, and Eddie Lopez
Animation by Mike Radjabov, Fabio Albertelli, and Jonny Hyman
Edited by Trenton Oliver
Slow Motion Camera: Shawn Sanders and Anthony Corrales
Sandcastle Timelapse by Greg LeBon and Archisand
Phantom rental from Panny Hire LA
Helicopter Pilots: Rick Shuster and Cliff Fleming
Helicopter Safety Officer: Ryan Hosking
FPV Drone Pilots: Sammie Saing and Josh Ewalt
Production Assistants: Roman Bacvic and Eddie Lopez
Intern: Katie Barnshaw
Additional video/photos supplied by Pond5 and Getty Images
Music from Epidemic Sound
Thumbnail by Ignat Berbeci
Produced by Derek Muller, Petr Lebedev, and Emily Zhang

A basketball and a 5kg medicine ball are dropped simultaneously. Which one hits the ground first? It seems obvious that the heavy one should accelerate at a greater rate and therefore land first because the force pulling it down is greater. But this is forgetting inertia - the tendency of mass to resist changes in motion. Therefore, although the force on the medicine ball is greater, it takes this larger force to accelerate the ball at the same rate as the basketball.

The surprising genius of Strandbeests. Fight the data brokers with Incogni. Head over to https://incogni.com/veritasium to get 60% off your annual subscription.

A massive thank you to Theo Jansen, to learn more about him and his Strandbeests check out: https://www.strandbeest.com/

A special thank you to Adam Savage, check out his channel Tested over at: https://www.youtube.com/tested

If you enjoyed the Strandbeest song at the end, you can hear the whole thing on our Patreon: https://www.patreon.com/posts/....by-popular-song-1174

Also on Patreon: an extended bonus interview with Adam Savage https://www.patreon.com/posts/117886682

0:00 Creation of the Beests
2:40 Learning to walk
6:50 Overcoming the sand
9:00 Surviving the storms
11:46 Building muscle
14:27 A developing brain
17:39 Fossils and decay
18:13 Strandbeests and climate change
19:16 Legacy
20:03 The Virus is Spreading

▀▀▀
Join us on Patreon for early access videos, bonus content, and to support Veritasium! https://ve42.co/PatreonDE

Patrons: Adam Foreman, Albert Wenger, Alexander Tamas, Anton Ragin, Autodidactic Studios, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, Evgeny Skvortsov, Farbod Mansorian, Garrett Mueller, Gnare, Greg Scopel, I. H., Juan Benet, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Spilmann Reed, TTST, Tj Steyn, Ubiquity Ventures, gpoly, meg noah, wolfee

If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV

▀▀▀

References: https://ve42.co/Refstrandbeest

Video and Image Credits:
Global Temperature Anomalies from 1880 to 2022 by via nasa.gov - https://ve42.co/temp188022
Adam Savage’s TestedAdam Savage's One Day Builds: Pedal-Powered Strandbeest! via Youtube - https://ve42.co/pedalbeest
greenmanbucket1980: Walter Cronkite on Climate Change via Youtube - https://ve42.co/cronkitecc
ThamesTvClimate Change | Global Warming | Pollution | This Week | 1988 via Youtube - https://ve42.co/1988ccnews
AP ArchiveUSA: VICE PRESIDENT AL GORE'S WARNING ON GLOBAL CLIMATE via Youtube - https://ve42.co/goresalarm
ThamesTvClimate Change - Warming Warning - 1981 via Youtube - https://ve42.co/1981warning
CBS New YorkReport Warns Of Rising Sea Levels via Youtube - https://ve42.co/searise
ShatnerMethodEarly Warnings of Climate Change Catastrophe - 1982 - CBS Evening News via Youtube - https://ve42.co/1982cbccc
The Weather NetworkNetherlands: Wind storm almost topples truck, tears roof off building via Youtube - https://ve42.co/dutchstorm
NBC NewsDeadly Storm Makes Crossing The Street A Battle In The Netherlands | NBC News via Youtube - https://ve42.co/stormbattle
Marcel OzymantraA clip from The Simpsons Season 28 Episode 10 "The Nightmare After Krustmas" via Youtube - https://ve42.co/simpsonscc
EngineezyI Built A Mechanical Walking Robot (with GPS) via Youtube - https://ve42.co/mechwalker
BigWR_永恒跳动的火焰Epic ride | Walking robot creature Strandbeest via Youtube - https://ve42.co/epicbeest
JK BrickworksLEGO Steampunk Walking Ship (Strandbeest) via Youtube - https://ve42.co/legobeest
The QEpic Cycling | Truly Unique Bicycle that Walks via Youtube - https://ve42.co/bikewalks
James BrutonBalancing Strandbeest via Youtube - https://ve42.co/beestbalance
TED-EdClosing the Dutch Maeslantkering (flood defence) | Timelapse via Youtube - https://ve42.co/floodclose
Peter TheobaldCentaur frame using Strandbeest mechanism - walking test via Youtube - https://ve42.co/centaurbot
The QDIY Walking Robotic Creature Strandbeest via Youtube - https://ve42.co/diybeest
HiroLabo OECUQuadruped Passive Walker by Strandbeest / Theo Jansen / LEGO via Youtube - https://ve42.co/quadwalker
Gabriel LaflammeStrandbeest 3d printed via Youtube - https://ve42.co/3dbeest
BigWR_永恒跳动的火焰Epic ride | Walking robot creature Strandbeest via Youtube - https://ve42.co/beestride
EngineezyI Built A Mechanical Walking Robot (with GPS) via Youtube - https://ve42.co/gpswalker
JKBrickworksLEGO Steampunk Walking Ship (Strandbeest) via Youtube - https://ve42.co/legoship
ZenichiWorksThe Playa Crawler Construction via Youtube - https://ve42.co/playabot
Concept BytesI built a WALKING coffee table via Youtube - https://ve42.co/walkingtable

▀▀▀
Directed by Casper Mebius
Written by Casper Mebius, Derek Muller and Petr Lebedev
Edited by Luke Molloy, Laura Mills, and Peter Nelson
Animated by Fabio Albertelli and Mike Radjabov
Illustrated by Jakub Misiek
Filmed by Casper Mebius, Rasoel Al Safar and Derek Muller
Additional research by Gabe Strong
Produced by Casper Mebius, Derek Muller, Leah Yost, Petr Lebedev, Rob Beasley Spence and Tori Brittain
Thumbnail contributions by Ben Powell, Ren Hurley and Peter Sheppard
Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound

A rare look inside the Svalbard Global Seed Vault which is closed ~350 days a year
Check out Audible: http://bit.ly/AudibleVe
More info on the seed vault: http://wke.lt/w/s/EKFlK
My trip to Norway was funded by Screen Australia, Film Victoria and Genepool Productions as part of a new project. More information soon.

Special thanks to Bente Naeverdal and the Crop Trust: https://www.croptrust.org

The biggest problems in the world might be solved by tiny molecules unlocked using AI. Take your big idea online today with https://ve42.co/hostinger - code VE at checkout.

A huge thank you to John Jumper and Kathryn Tunyasuvunakool at Google Deepmind; and to David Baker and the Institute for Protein Design at the University of Washington for their invaluable expertise and explanations.

We’re incredibly grateful to Juanita Bagawan and Lucie Kerley at Google Deepmind, and Ian C. Haydon at the UW Institute for Protein Design for their assistance with some of the animation and imagery used in this video.

Special thanks to those at Google DeepMind Production Studios for their help interviewing John Jumper:
Director - Bernardo Resende
Director of Photography - Robert Messere
Senior Audio Technician - Perry Rogantin
Senior Production Coordinator - Sarah Ellen Morton
Studio Manager - Nicholas Duke

For more on this topic head over to our Patreon for the exclusive extended interview https://www.patreon.com/posts/patreon-with-cut-122274530?utm_medium=clipboard_copy&utm_source=copyLink&utm_campaign=postshare_creator&utm_content=join_link

▀▀▀
0:00 How to determine protein structures
3:50 Why are proteins so complicated?
5:34 The CASP Competition and Deep Mind
9:08 How does Alphafold work?
12:06 3 ways to get better AI
14:24 What is a Transformer in AI?
17:15 The Structure Module
18:35 Alphafold 2 wins the Nobel Prize
20:36 Designing New Proteins - RF Diffusion
22:58 The Future of AI

▀▀▀
Try Snatoms! A molecular modelling kit I invented where the atoms snap together.
https://ve42.co/SnatomsV

Sign up to the Veritasium newsletter for weekly science updates - https://ve42.co/Newsletter

▀▀▀
References and Credits:
How AI Revolutionized Protein Science, but Didn’t End It. (Jun 2024) via Quanta Magazine - https://ve42.co/airev
Jumper, J., Evans, R., Pritzel, A. et al. (Jul 2021). Highly accurate protein structure prediction with AlphaFold. Nature - https://ve42.co/alphafoldtwo
Senior, A.W., Evans, R., Jumper, J. et al. (Jan 2020). Improved protein structure prediction using potentials from deep learning. Nature - https://ve42.co/alphafold
R Zwanzig, A Szabo, B Bagchi (Jan 1992). Levinthal's paradox. PMC, National Institute of Health - https://ve42.co/levparadox
Khatib, F., DiMaio, F., Foldit Contenders Group. et al. (Sept 2011). Crystal structure of a monomeric retroviral protease solved by protein folding game players. Nature - https://ve42.co/proteinfoldingsolved
DeepMind co-founder: Gaming inspired AI breakthrough. (Dec 2020) via BBC - https://ve42.co/aibreakthrough
3Blue1Brown. (Apr 2024). Transformers (how LLMs work) explained visually | DL5 via Youtube - https://ve42.co/transformers
AlphaFold impact stories. via Deepmind Blog - https://ve42.co/foldimpact
Quanta Magazine. (Oct 2024). How AI Cracked the Protein Folding Code and Won a Nobel Prize via Youtube - https://ve42.co/proteinfolding
Looking Glass Universe. (Apr 2024). how AlphaFold *actually* works via Youtube - https://ve42.co/foldworks
Google DeepMind. (Nov 2020). AlphaFold: The making of a scientific breakthrough via Youtube - https://ve42.co/alphafoldvideo
Nobel Prize. (Dec 2024). 2024 Nobel Prize lectures in chemistry | David Baker, Demis Hassabis and John Jumper via Youtube - https://ve42.co/nobelchem
The AlphaFold2 Method Paper: A Fount of Good Ideas. (Jul 2021) via moalquraishi.wordpress - https://ve42.co/Alphafoldpaper
Why Don't We Have More Protein-Protein Drug Molecules? (Dec 2009) via Science - https://ve42.co/proteindrugmol
Data sonification. via Carla Scaletti - https://ve42.co/datasonification

Images & Video:
Available here - https://ve42.co/alphafoldvisuals

And if you want to learn more about how we have been making antivenom check out our previous video How Horses Save Humans From Snakebites - https://ve42.co/veantivenom

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Special thanks to our Patreon supporters:

Adam Foreman, Albert Wenger, Alexander Tamas, Anton Ragin, Autodidactic Studios, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, Greg Scopel, I. H., Juan Benet, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Spilmann Reed, Tj Steyn, TTST, Ubiquity Ventures, wolfee

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Directed by Sumeet Kulkarni
Written by Sumeet Kulkarni, Derek Muller and Zoe Heron
Edited by Jack Saxon
Animated by Ivy Tello, Emma Wright, Andrew Neet and Fabio Albertelli
Illustrated by Jakub Misiek
Filmed and demos done by Sumeet Kulkarni
Additional research by Geeta Thakur, Vincent Cheng and Emilia Gyles
Produced by Sumeet Kulkarni, Derek Muller, Zoe Heron, Rob Beasley Spence and Tori Brittain
Thumbnail contributions by Ren Hurley, Peter Sheppard and Ben Powell
Additional video/photos supplied by Getty Images and Storyblocks
Music from Epidemic Sound

Droplets levitate on a bath of liquid nitrogen and are spontaneously self-propelled. Thanks Audible! Start a 30-day trial and your first audiobook is free. Go to https://audible.com/VERITASIUM or text VERITASIUM to 500500.

Special thanks to Dr. Anaïs Gauthier
Physics of Fluids: https://pof.tnw.utwente.nl/

Self-propulsion of inverse Leidenfrost drops on a cryogenic bath
Anaïs Gauthier, Christian Diddens, Rémi Proville, Detlef Lohse, and Devaraj van der Meer
PNAS January 22, 2019 116 (4) 1174-1179; published ahead of print January 22, 2019
https://www.pnas.org/content/116/4/1174

For a detailed description of the setup:
http://www.lps.ens.fr/~adda/pa....piers/Langmuir2016.p

And self-propulsion is also seen: http://www.lps.ens.fr/~adda/pa....piers/InvLeidenfrost

Other recent (hot) Leidenfrost experiments that might be interesting:
* Leidenfrost wheels: https://www.youtube.com/watch?v=glRGl-eYuXo
* Leidenfrost maze: https://www.youtube.com/watch?time_continue=174&v=vPZ7sx3EwUY
* Leidenfrost explosions: https://www.youtube.com/watch?v=z0sp3AjgUy4

Special thanks to Patreon supporters:
Donal Botkin, James M Nicholson, Michael Krugman, Nathan Hansen, Ron Neal, Stan Presolski, Terrance Shepherd

Thanks to Prof. Kevin McKeegan at UCLA for the liquid nitrogen

Filming by Raquel Nuno

Additional animations by Alan Chamberlain

You probably don’t understand how a rainbow really works. Get a little smarter every day with Brilliant. Visit https://brilliant.org/veritasium to get 20% off your annual premium subscription.

Special thanks to Mats Vermeeren.

00:00 Most people don't understand rainbows
01:08 Light refraction explained
08:20 How does a rainbow form?
13:10 Circular rainbows
15:14 Why are rainbows curved?
17:30 Why can’t you see a rainbow with sunglasses?
18:43 Why is it brighter underneath a rainbow?
20:44 Different types of rainbow
23:46 Invention of the cloud chamber

▀▀▀
Join us on Patreon for early access videos, bonus content, and to support Veritasium! https://ve42.co/PatreonDE

Patrons: Adam Foreman, Albert Wenger, Alexander Tamas, Anton Ragin, Balkrishna Heroor, Bertrand Serlet, Bill Linder, Blake Byers, Bruce, Dave Kircher, David Johnston, Evgeny Skvortsov, Farbod Mansorian, Garrett Mueller, Gnare, Greg Scopel, I. H., John H. Austin, Jr., Juan Benet, KeyWestr, Kirill Shore, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Spilmann Reed, TTST, Tj Steyn, Ubiquity Ventures, gpoly, john kiehl, meg noah, wolfee

If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV

CORRECTION: We mistakenly used picture of the portrait artist Henry Tanworth Wells at 23:54. It should be a picture of CTR Wilson. Sorry! Thanks, @manicpixiedreambuoy, for pointing it out.

CORRECTION: The animation at 18:06 shows only the parallel polarization being transmitted, when in reality both parallel and perpendicular polarization light gets transmitted. Perpendicularly polarized light doesn't exhibit a Brester's angle so there's always both reflection and transmission when going from a high index of refraction material to a low index of refraction material.

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References: https://ve42.co/RefsRainbows

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Directed by Pablo Rovetto and Derek Muller
Written by Pablo Rovetto and Derek Muller
Edited by Nick Lear and Trenton
Animated by Mike Radjabov, Ivy Tello, David Szakaly, Emma Wright and Fabio Albertelli
Filmed by Derek Muller
Additional research by Gabe Strong and Geeta Thakur
Produced by Pablo Rovetto, Derek Muller, Emily Zhang, Rob Beasley Spence and Tori Brittain
Thumbnail contributions by Jakub Misiek, Ren Hurley and Peter Sheppard
Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound

Key aspects of pyramid construction from quarry to completion.
Check out Audible: http://bit.ly/AudibleVe
Live show in Alabama: http://bit.ly/VeRAOI

The most common misconception about the pyramids is that they were built by slaves. Recent archeological evidence suggests they were instead constructed by paid workers. Some may have performed this work as a form of tax payment for several months of the year. Skilled engineers would have planned and orchestrated the building. An estimated 10,000-20,000 people would have been working on a pyramid at any one point in time. They were well fed and provided with shelter near the pyramids. Plus their burial sites close by indicate they were respected and were not slaves.

Much of the limestone was quarried from the Giza plateau itself, meaning the stones did not need to be transported far. The granite casing of Menkaure's pyramid, on the other hand, was transported from Aswan, around 600 miles, or 1000 km up the Nile.

Editing assistance by Dustin Chow

Music by Kevin MacLeod, Incompetech.com "Desert City" and "Ibn Al-Noor"

How a single phone call from a student helped uncover a flaw that nearly toppled Citicorp. Get an exclusive 15% discount on Saily data plans! Use code veritasium at checkout. Download Saily app or go to https://saily.com/veritasium

If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV

Correction: From construction images of Citicorp, sharp-eyed viewers might see that the mid-V columns are still there. Those columns help prevent buckling of the diagonal and the weight of people on the floor above, but do not take the majority of the gravity load. So we left them out of our diagram to clearly explain the load paths. See page 70 of this source for more details - https://drive.google.com/file/....d/1ODFo66-_V7Y9vKANb

Sign up to the Veritasium newsletter for weekly science updates - https://ve42.co/Newsletter

▀▀▀
0:00 Why is the citicorp building on stilts?
4:44 How wind load works
7:49 Tuned Mass Dampers
11:17 The Anonymous Student
14:00 Quartering Winds
18:38 What were the odds of collapse?
20:31 How was the citicorp building fixed?
25:40 Hurricane Ella
27:00 TMDs Take Over The World
28:36 Conspiracies and Cover Ups

▀▀▀
A big thank you for the incredible people without whom we couldn't have done this! 🖤

To Michael Greenburg, author of The Great Miscalculation, for his insights that really brought the story and its context to life. He gave us a pre-copy of his upcoming book, and it is fantastic: https://ve42.co/Miscalc
To Eric Hines for all his help with the technical details, fact-checking, and making sure we got the engineering right.
To Michael J. Vardaro for helping us uncover the details of the story and the resources he provided.
To Brock Hedegaard for helping us dive deep into the Citicorp structural analysis. Learn the fundamentals of structural analysis on his brilliant channel, @StructuresProfH, and see here for his analysis of the citicorp center; https://www.youtube.com/watch?v=lE_DspFE2ZM
To Michele Barbato from UC Davis for his inputs on the load calculations.
https://faculty.engineering.ucdavis.edu/barbato/
Matt from @mvvvc for talking us through his wind load analysis.
To Prof. Chris Letchford who helped us understand the impact of wind on Citicorp's structure.
To DongHun Yeo from NIST for discussing his research about wind effects on buildings similar to citicorp: https://ve42.co/WindLoad
Finally, to Team Columbia —who built the epic TMD and ran wind tunnel experiments that made this story come alive.
This includes the folks at the Mechanical Engineering Teaching Laboratory
(Follow all the cool stuff they’re doing: @mechcu, @columbiaengineering or visit https://teachinglab.me/)
Amanda Lombardo, Manager of Instructional Laboratories
Daniela Durón García, Assistant Manager of Instructional Laboratories
Jorge Casas, Machinist
And the amazing seniors from the Columbia Space Initiative:
(Support their awesome work here: columbiaspace.org/support-us/, Follow them: @columbiaspaceinitiative)
Michael Sheehan
Claudio Solano
Jessica Bolar
Kathryn Lampo

▀▀▀
References:
Michael M. Greenburg. The Great Miscalculation via. nyupress.org - https://ve42.co/Miscalc
Joe Morgenstern. The Fifty-Nine-Story Crisis via. The New Yorker - https://ve42.co/59Crisis
National Academy of Engineering. William LeMessurier-The Fifty-Nine-Story Crisis: A Lesson in Professional Behavior - https://www.youtube.com/watch?v=um-7IlAdAtg
Diane Lee Hartley. Implications of a Major Urban Office Complex: The Scientific, Social and Symbolic Meanings of Citicorp Center via. princeton.edu - https://ve42.co/CitiSymbol
Addition References here: https://ve42.co/citiref

▀▀▀
Special thanks to our Patreon supporters:
Adam Foreman, Albert Wenger, Alex Porter, Alexander Tamas, Anton Ragin, Autodidactic Studios, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, David Tseng, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, Greg Scopel, HydrochloRick, Jon Jamison, Juan Benet, Keith England, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Tj Steyn, TTST, Ubiquity Ventures, wolfee

▀▀▀
Written and Directed by Sulli Yost
Edited by Trenton Oliver
Additional Editing by Axel Oliver, James Horsley and Peter Nelson
3D Modeling by Maydelis Anaya Romero
Animation by Mike Radjabov, Andrew Neet, Fabio Albertelli, Jakub Misiek, and Emma Wright
Illustration by Jakub Misiek, Maria Gusakovich and Cainejan Esperanza
Filmed by Sulli Yost, Henry van Dyck, Andrew Abballe, Derek Muller
Produced by Sulli Yost, Derek Muller, Casper Mebius, Zoe Heron, Rob Beasley Spence and Tori Brittain
Additional research by Geeta Thakur
Thumbnail contributions by Ren Hurley and Ben Powell
Additional video/photos supplied by Getty Images, Pond5, Axiom Images and Storyblocks
Music from Epidemic Sound

How the brain works, how we learn, and why we sometimes make stupid mistakes.
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This video was inspired by the book Thinking Fast and Slow by Daniel Kahneman

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Filmed by Raquel Nuno

Music by Kevin MacLeod, http://incompetech.com "Sneaky Adventure" "Harlequin"

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A huge thank you to Emeritus Professor Cecil R. Reynolds and Dr. Stuart J. Ritchie for their expertise and time.

Also a massive thank you to Prof. Steven Piantadosi and Prof. Alan S. Kaufman for helping us understand this complicated topic. As well as to Jay Zagrosky from Boston University's Questrom School of Business for providing data from his study.

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References:
Kaufman, A. S. (2009). IQ testing 101. Springer Publishing Company.

Reynolds, C. R., & Livingston, R. A. (2021). Mastering modern psychological testing. Springer International Publishing.

Ritchie, S. (2015). Intelligence: All that matters. John Murray.

Spearman, C. (1961). " General Intelligence" Objectively Determined and Measured. - https://ve42.co/Spearman1904

Binet, A., & Simon, T. (1907). Le développement de l'intelligence chez les enfants. L'Année psychologique, 14(1), 1-94.. - https://ve42.co/Binet1907

Intelligence Quotient, Wikipedia - https://ve42.co/IQWiki

Radiolab Presents: G. - https://ve42.co/RadioLabG

McDaniel, M. A. (2005). Big-brained people are smarter: A meta-analysis of the relationship between in vivo brain volume and intelligence. Intelligence, 33(4), 337-346. - https://ve42.co/McDaniel2005

Deary, I. J., Strand, S., Smith, P., & Fernandes, C. (2007). Intelligence and educational achievement. Intelligence, 35(1), 13-21. - https://ve42.co/Deary2007

Lozano-Blasco, R., Quílez-Robres, A., Usán, P., Salavera, C., & Casanovas-López, R. (2022). Types of Intelligence and Academic Performance: A Systematic Review and Meta-Analysis. Journal of Intelligence, 10(4), 123. - https://ve42.co/Blasco2022

Kuncel, N. R., & Hezlett, S. A. (2010). Fact and fiction in cognitive ability testing for admissions and hiring decisions. Current Directions in Psychological Science, 19(6), 339-345. - https://ve42.co/Kuncel2010

Laurence, J. H., & Ramsberger, P. F. (1991). Low-aptitude men in the military: Who profits, who pays?. Praeger Publishers. - https://ve42.co/Laurence1991

Gregory, H. (2015). McNamara's Folly: The Use of Low-IQ Troops in the Vietnam War; Plus the Induction of Unfit Men, Criminals, and Misfits. Infinity Publishing.

Gottfredson, L. S., & Deary, I. J. (2004). Intelligence predicts health and longevity, but why?. Current Directions in Psychological Science, 13(1), 1-4. - https://ve42.co/Gottfredson2004

Sanchez-Izquierdo, M., Fernandez-Ballesteros, R., Valeriano-Lorenzo, E. L., & Botella, J. (2023). Intelligence and life expectancy in late adulthood: A meta-analysis. Intelligence, 98, 101738. - https://ve42.co/Izquierdo2023

Zagorsky, J. L. (2007). Do you have to be smart to be rich? The impact of IQ on wealth, income and financial distress. Intelligence, 35(5), 489-501. - https://ve42.co/Zagorsky2007

Strenze, T. (2007). Intelligence and socioeconomic success: A meta-analytic review of longitudinal research. Intelligence, 35(5), 401-426. - https://ve42.co/Strenze2007

Deary, I. J., Pattie, A., & Starr, J. M. (2013). The stability of intelligence from age 11 to age 90 years: the Lothian birth cohort of 1921. Psychological science, 24(12), 2361-2368. - https://ve42.co/Deary2013

Flynn, J. R. (1987). Massive IQ gains in 14 nations: What IQ tests really measure. Psychological bulletin, 101(2), 171. - https://ve42.co/Flynn1987

Why our IQ levels are higher than our grandparents' | James Flynn, TED via YouTube - https://www.youtube.com/watch?v=9vpqilhW9uI

Duckworth, A. L., Quinn, P. D., Lynam, D. R., Loeber, R., & Stouthamer-Loeber, M. (2011). Role of test motivation in intelligence testing. Proceedings of the National Academy of Sciences, 108(19), 7716-7720. - https://ve42.co/Duckworth2011

Kulik, J. A., Bangert-Drowns, R. L., & Kulik, C. L. C. (1984). Effectiveness of coaching for aptitude tests. Psychological Bulletin, 95(2), 179. - https://ve42.co/Kulik1984

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Written by Derek Muller, Casper Mebius, & Petr Lebedev
Edited by Trenton Oliver
Filmed by Derek Muller, Han Evans, & Raquel Nuno
Animation by Fabio Albertelli & Ivy Tello
Additional video/photos supplied by Getty Images & Pond5
Music from Epidemic Sound
Produced by Derek Muller, Casper Mebius, & Han Evans