I have the photic sneeze reflex so I sneeze when I look at bright light.
Check out 23andMe: http://ve42.co/23andme
*So technically the single nucleotide swap (C instead of T) is not actually in a gene per se but in an intergenic region on chromosome 2. It's also not clear exactly how this affects physiology or causes the sun sneeze but there is correlative evidence that every copy of this single nucleotide polymorphism (SNP) is associated with a 1.3x increase in likelihood of having the photic sneeze reflex.

I have wanted to make a video about sun-sneezing for a long time. It is something I've experienced my whole life. When I go from a dark room indoors into full sunlight I invariably sneeze. I thought everyone did it. So my original question was why do people sneeze when they see bright light? That led me to consider what possible evolutionary advantages there could be to sneezing in sunlight. The obvious advantage to me is that sunlight kills pathogens of which there may be many in your snot or mucus. So sneezing in sunshine is a much better idea than sneezing inside a dark, damp cave where you may be living.

For more info, check out:
Web-Based, Participant-Driven Studies Yield Novel Genetic Associations for Common Traits
http://journals.plos.org/plosg....enetics/article?id=1

Filmed by Raquel Nuno

The definitive answer about the direction water swirls in two hemispheres
Sync the videos yourself: http://toiletswirl.com

For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time.

The idea that water going down a drain or flushed down a toilet swirls in opposite directions in the Northern and Southern Hemispheres has a long history. But few have ever done the experiment. Destin from Smarter Every Day and I performed identical experiments in the Northern and Southern hemispheres. What we found is the direction of water swirl in a toilet, sink, or bathtub is determined by other sources of angular momentum. However if the body of water is big enough, e.g. a kiddy pool, and left still for long enough (at least 24 hours), then the Coriolis effect is observable with water swirling counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere.

Veritasium on Instagram: http://instagram.com/veritasium
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Smarter Every Day Instagram: http://instagram.com/smartereveryday
Patreon Support Link: http://www.patreon.com/smartereveryday
Twitter: http://twitter.com/smartereveryday
www.facebook.com/SmarterEveryDay

Gordon McGladdery did all of the sound design for the video. We used two songs from other artists (licensed of course). Derek split the first one up so it fades from video to video, and Gordon split the instruments up on the second one. There are violins on one video and percussion on the other for example. It's really neat.

The neat earth animation at the beginning and the synchronizing timer was made by http://eisenfeuer.com/. He also made still images of the earth from the top and the bottom.

Thanks to Vanessa for filming in Sydney: http://youtube.com/braincraftvideo

MORE INFO:

There was a study performed at MIT years ago (http://web.mit.edu/hml/ncfmf/09VOR.pdf) that explained the physics involved. We repeated some of these demonstrations, but on opposite sides of the globe…and in a way that can be easily understood.
This site is a great resource on the Coriolis effect and ways people have gotten it wrong:
http://www.ems.psu.edu/~fraser/Bad/Ba...

A pulsing black hole in the centre of a distant galaxy sheds light on black hole and galaxy formation. How fast are black holes rotating and how does that rotation change over its life-span?

Huge thanks to Prof. Geraint Lewis and study author Dr. Dheeraj Pasham.

A loud quasi-periodic oscillation after a star is disrupted
by a massive black hole
https://ve42.co/pasham

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

Music from http://epidemicsound.com "Colorful animation 4" "serene story 2" "To the stars 01" "Black Vortex

Animations by Alan Chamberlain and courtesy of NASA

The Vikings suffered many hardships living in the north of Europe: long, cold winters and importantly a lack of sunlight. Luckily, they had cod.
Check out Vitamania: https://ve42.co/cod

When making a video about vitamins I thought the story would mainly be about supplement pills, whether we should or shouldn't take them and how they're made. But what I found out is vitamins have a remarkable story that affects many more aspects of our lives. For example the Vikings needed a source of vitamin D to last the dark winter months and for their children to develop strong, healthy bones, avoiding rickets.

Special thanks to Patreon supporters:
a human, Albert Jachowicz-Brzeziński, Alfred Wallace, Arjun Chakroborty, Brent Stewart, Chris Vargas, Chuck Lauer Vose, Clip Tree, Coale Shifflett, Colin Bellmore, DALE HORNE, Eric Velazquez, Fedor Indutny, Fran Rodriguez, James Wong, Jasper Xin, Joar Wandborg, Johnny, Jorge Angel Sandoval, June Kang, Kevin Beavers, Kishore Tipirneni, Levan Ferr, Listen Money Matters, Manuel Zürcher, Mark Bevilacqua, Mathias Göransson, Michael Bradley Wirz, Michael Krugman, Mohammed Al Sahaf, Nicholas Hastings, OddJosh, Patrick Čalija, Peter Tajti, Philipp Volgger, Roberto Rezende, Robin DeBank, Ron Neal, Stan Presolski, Swante Scholz, Tiago Bruno, Tige Thorman, Warrior8252

This video was filmed by Harry Panagiotidis
Researched and written by Derek Muller and Jonny Hyman
Editing, animation and music by Jonny Hyman
Cod liver oil animation by Ivy Tello
Vitamania was written, directed and produced by Sonya Pemberton

How a feud in Russia led to modern prediction algorithms.
👉 To try everything Brilliant has to offer for free for a full 30 days, visit https://brilliant.org/veritasium. You’ll also get 20% off an annual premium subscription.

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

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

▀▀▀
A huge thank you to Brian Hayes, David Aldous, Geoff Engelstein, Jeffrey Rosenthal, Jimmy He, Mark Priestley, Michael Choi, Peter Norvig, Sam Power, and Thomas Haigh for their invaluable expertise and contributions to this video.

And a special thank you to Madeline Johnson for her excellent fact-checking.

▀▀▀
0:00 The Law of Large Numbers
4:37 What is a Markov Chain?
9:43 Ulam and Solitaire
12:21 Nuclear Fission
15:46 The Monte Carlo Method
16:32 The first search engines
19:07 Google is born
25:16 How does predictive text work?
27:10 Are Markov chains memoryless?
29:41 How to perfectly shuffle a deck of cards

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References:
https://ve42.co/RefsMarkov

Images & Video:
https://ve42.co/7Z

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Special thanks to our Patreon supporters:

Adam Foreman, Albert Wenger, Alex Porter, Alexander Tamas, Anton Ragin, armedtoe, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Dave Kircher, David Johnston, David Tseng, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, Ibby Hadeed, JT, Jeromy Johnson, Jon Jamison, Juan Benet, Keith England, KeyWestr, Kyi, Lee Redden, Meekay, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Bush, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Robert Oliveira, Sam Lutfi, TTST, Tj Steyn, Ubiquity Ventures, wolfee

▀▀▀
Writers: Kaela Albert, Casper Mebius & Derek Muller
Producer & Director: Kaela Albert
Editors: Peter Nelson & Jack Saxon
Camera Operators: Gabe Strong, Gregor Cavlovic & Derek Muller
Animator: Andrew neet, Emma Wright, Fabio Albertelli & Ivy Trello
Illustrator: Caine Esperanzo, Jakub Misiek & Maria Gustanovich
Assistant Editor: James Stuart
Researchers: Darius Garewal, Gabe Strong & Emilia Gyles
Thumbnail Designers: Ren Hurley & Ben Powell
Production Team: Rob Beasley Spence, Casper Mebius, Sulli Yost and Henry Van Dyck
Executive Producers: Derek Muller & Casper Mebius
Additional video/photos supplied by Getty Images, Pond5 and Storyblocks
Music from Epidemic Sound

The kilogram, mole, kelvin, and ampere will be redefined by physical constants. For a limited time, get 3 months of Audible for just $6.95 a month: http://audible.com/VERITASIUM or text VERITASIUM to 500500

Will this be the last video I make about SI units? Quite possibly. There's something about being so precise and defining the systems within which science works. When we can more accurately and routinely measure a kilogram, a mole, a kelvin and an ampere, then we can make better observations, we can better detect anomalies and improve our theories. That is why this is so important to me.

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

Special thanks to NIST: http://nist.gov

Additional graphics by Ignat Berbeci

Music from http://epidemicsound.com "Experimental1"

Made for ABC TV Catalyst http://www.abc.net.au/catalyst/ as an extended version of my Comparing Temperatures video: http://www.youtube.com/watch?v=hNGJ0WHXMyE

Here’s what happens when you just keep zooming in. Use code veritasium at https://incogni.com/veritasium to get an exclusive 60% off an annual Incogni plan.

A big thank you to Magnus Garbrecht from the University of Sydney for showing us around the lab and for his feedback on the script.

Special thanks to Quentin Ramasse for his expertise on the video.

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

▀▀▀
0:00 Why is it hard to see atoms?
2:12 How does an electron microscope work?
4:09 Transmission Electron Microscope (TEM)
5:11 Spherical Aberration
8:55 Field Ion Microscope
11:05 Scanning Transmission Electron Microscope (STEM)
13:24 Probe microscopes
14:02 An unlikely solution
18:08 Seeing atoms

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

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, 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, 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:
Busch, H. (1926). Berechnung der Bahn von Kathodenstrahlen im axialsymmetrischen elektromagnetischen Felde. Annalen Der Physik - https://ve42.co/Busch1926
Ruska, E. (1986). The development of the electron microscope and of electron microscopy. Nobel Lecture - https://ve42.co/Ruska1986
Scherzer, O. (1936) - https://ve42.co/Scherzer1936
Jensen, G. (2015). Part 1: EM Lenses. Caltech - https://ve42.co/Jensen2015
Field Ion Microscope via Wikipedia - https://ve42.co/FieldIon
Transmission Electron Microscope via Wikipedia - https://ve42.co/MicroscopeTEM
Albert V. Crewe biography via UChicagoNews Microscopy Society of America - https://ve42.co/CreweBio
McMullan, D. (1993). Scanning Electron Microscopy 1928 - 1965. Microscopy Society of America, Cincinnati - https://ve42.co/McMullan1993
Electric and Magnetic Field Lenses via MIT - https://ve42.co/LensesMIT
Haider, M. et al. (1998). Towards 0.1 nm resolution with the first spherically corrected transmission electron microscope. Journal of Electron Microscopy - https://ve42.co/Haider1998_1
Haider, M. et al. (1998). Electron microscopy image enhanced. Nature - https://ve42.co/Haider1998_2
Krivanek, O. et al. (2022). Aberration correction in the STEM. CRC Press EBooks - https://ve42.co/Krivanek2022
Crewe, A. V., et al. (1970). Visibility of Single Atoms. Science - https://ve42.co/Crewe1970
Secrets of Size: Atoms to Supergalaxies via the BBC - https://ve42.co/AtomsBBC
Pennycook, S. J. (2012). Seeing the atoms more clearly: STEM imaging from the Crewe era to today. Ultramicroscopy - https://ve42.co/Pennycook2012
Rose, H. H. (2009). Historical aspects of aberration correction. Journal of Electron Microscopy - https://ve42.co/Rose2009
Kavli Prize in Nanoscience via kavliprize.org - https://ve42.co/Kavli2020
Vogt, T. (2019) Aberration-Corrected Electron Microscopy - https://ve42.co/Vogt2019

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

▀▀▀
Directed by Gregor Čavlović, Derek Muller, and Tim Usborne
Written by Gregor Čavlović, Tim Usborne, Emily Zhang, and Casper Mebius
Edited by Trenton Oliver and Charlie Grayley
Animated by Mike Radjabov, Fabio Albertelli, Ivy Tello, Emma Wright, and Andrew Neet
Illustrated by Jakub Misiek and Maria Gusakovich
Filmed by Charles Clements
Additional research by Gabe Strong, Geeta Thakur, and Emili Gyles
Produced by Casper Mebius, Derek Muller, Emily Zhang, Gregor Čavlović, Rob Beasley Spence, Tori Brittain, Gabe Strong, Luke Lewis, and Matthew Cavanagh
Thumbnail contributions by Ben Powell, Ren Hurley, and Peter Sheppard
Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound

The mistakes of Amelia Earhart’s final flight, and the physics that could have saved her. Use code VERITASIUM to get 50% off your 1st club crate when you join a club for kids aged 3+ or go to https://kiwico.com/veritasium

00:00 Amelia Earhart’s final flight
03:33 Who was Amelia Earhart?
05:36 The flight plan
07:13 How celestial navigation works
09:16 Invention of radio technology
12:02 Radio waves explained
22:44 Earhart makes her critical decision
24:55 Communication failures
28:30 “Gas is running low”
31:39 Her desperate final message
33:01 The small detail that could have saved her

Special thanks to Clifford Heath for his help putting together the radio demo, and the folks at the Victorian ARDF group for connecting us.

Thank you to Brian Harrison and Michael Murphy with the AWA Communication Technologies Museum for their assistance with early research.

Thank you to Peter Bevelacqua over at Antenna Theory for help filling in some missing details.

Sharp-eyed viewers might notice there doesn't seem to be a loop antenna in the flight simulation shots. It sadly wasn't included in the simulator's model of Earhart's Electra, but it features prominently in old photos.

The Secret Life of Radio video credits: Tim Hunkin - https://www.youtube.com/watch?si=4AyDKVi6brMqSIMD&v=LMxate9gegg&feature=youtu.be

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, 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, Reed Spilmann, Richard Sundvall, Sam Lutfi, 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

References: https://ve42.co/RefsEarhart

Directed by Sulli Yost and Derek Muller
Written by Sulli Yost and Derek Muller
Edited by Peter Nelson
Animated by David Szakaly, Fabio Albertelli, Ivy Tello, Mike Radjabov, Mohamed Alhaj, Emma Wright
Illustrations by Jakub Misiek, Emma Wright, Maria Gusakovich
Filmed by Derek Muller and Bernard Lau
Additional Research by Gabriel Strong, Geeta Thakur
Produced by Sulli Yost, Derek Muller, Rob Beasley Spence, Emily Lazard, Tori Brittain, Umar Ijaz
Thumbnail contributions by Peter Sheppard, Ren Hurley
Additional video/photos supplied by Getty Images and Storyblocks
Music from Epidemic Sound and Jonny Hyman

Democracy might be mathematically impossible – here’s why. Head to https://brilliant.org/veritasium to start your free 30-day trial and get 20% off an annual premium subscription.

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

▀▀▀
Massive thanks to Prof. Eric Maskin for helping with the script. Thanks to Chris Dong for inspiring this video. Massive thanks to Latif Nasser for being part of this video. Massive thanks to Curtis Gilberts, and to Radiolab -- listen to their great episode on voting systems here https://radiolab.org/podcast/tweak-vote

▀▀▀

A few great proofs of Arrow’s impossibility theorem:
Yu, N. N. (2012). A one-shot proof of Arrow's impossibility theorem. Economic Theory, 523-525.- https://ve42.co/Yu2012
Geanakoplos, J. (2005). Three brief proofs of Arrow’s impossibility theorem. Economic Theory, 26(1), 211-215. - https://ve42.co/Geanakoplos2005

References:
Arrow, K. J. (2012). Social choice and individual values (Vol. 12). Yale university press. - https://ve42.co/Arrow2012
Arrow, K. J. (1950). A Difficulty in the Concept of Social Welfare. Journal of Political Economy - https://ve42.co/Arrow1950
Black, D. (1948). On the rationale of group decision-making. Journal of political economy, 56(1), 23-34. - https://ve42.co/Black1948
Black, D. (1969). On Arrow's impossibility theorem. The Journal of Law and Economics, 12(2), 227-248. - https://ve42.co/Arrow1969
Maskin, E., & Sen, A. (2014). The Arrow impossibility theorem. Columbia University Press. - https://ve42.co/Maskin2014
Gehrlein, W. V., & Valognes, F. (2001). Condorcet efficiency: A preference for indifference. Social Choice and Welfare - https://ve42.co/Gehrlein2001
Dardanoni, V. (2001). A pedagogical proof of Arrow's Impossibility Theorem. Social Choice and Welfare, 18(1), 107-112. - https://ve42.co/Dardanoni2001
McCune, D., & Wilson, J. (2023). Ranked-choice voting and the spoiler effect. Public Choice, 196(1), 19-50. - https://ve42.co/McCune2023
Santucci, J. (2021). Variants of ranked-choice voting from a strategic perspective. Politics and Governance, 9(2), 344-353. - https://ve42.co/Santucci2021
Kaminski, M. M. (2018). Spoiler effects in proportional representation systems: evidence from eight Polish parliamentary elections, 1991–2015. Public Choice, 176(3), 441-460. - https://ve42.co/Kaminski2018
Brams, S. J., & Fishburn, P. C. (1978). Approval voting. American Political Science Review, 72(3), 831-847. - https://ve42.co/Brams1978

Other references and election results - https://ve42.co/IODRefs

Images & Video:
Minneapolis 2013 Debate Images: https://ve42.co/Minn2013Debate
4 Images from this article: https://ve42.co/MinnDebateMPR
Arrow Nobel Prize Image from NYT Article: https://ve42.co/ArrowNYT

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

▀▀▀
Directed by Petr Lebedev and Derek Muller
Written by Petr Lebedev and Derek Muller
Edited by Trenton Oliver
Animated by Fabio Albertelli, Jakub Misiek and Ivy Tello
Filmed by Derek Muller
Additional Research by Gabriel Strong
Produced by Petr Lebedev, Derek Muller, Gabriel Strong, Rob Beasley Spence, Emily Lazard, Luke Lewis
Thumbnail contributions by Jakub Misiek, Ren Hurley, Peter Sheppard
Additional video/photos supplied by Getty Images
Music from Epidemic Sound

#democracy #voting #mathematics

Glass is one of the most important materials humans have ever made. Try out Saily by heading to https://saily.com/veritasium and remember to use coupon code veritasium to get 15% off your first purchase.

00:00 Glass and our place in the universe
01:23 How Gorilla Glass works
04:35 What is glass?
05:15 Is glass a liquid?
07:29 Different types of glass
09:59 Invention of transparent glass
11:56 Why is some glass transparent?
14:54 Invention of glass lenses
15:52 Development of magnification
18:02 How to make glass more durable

▀▀▀
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, 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, Reed Spilmann, Richard Sundvall, Sam Lutfi, 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

▀▀▀

References: https://ve42.co/GlassReferences

▀▀▀
Directed by Petr Lebedev
Written by Petr Lebedev and Derek Muller
Edited by Nick Lear
Animated by Fabio Albertelli, Ivy Tello, David Szakaly and Rokas Viksraitis
Illustrated by Jakub Misiek, Emma Wright, and Maria Gusakovich
Filmed by Petr Lebedev, Sulli Yost and Miranda Prise
Additional research by Gabe Strong, Geeta Thakur
Produced by Petr Lebedev, Derek Muller, Rob Beasley Spence, Gabe Strong, 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

This is the history of Monsanto’s herbicides… Sponsored by Incogni - Use code veritasium at https://incogni.com/veritasium to get an exclusive 60% off.

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

▀▀▀
A huge thank you to Carey Gillam at the New Lede, Nathan Donley at the Center for Biological Diversity, and Bart Elmore at Ohio State University for their time and expertise on the topic.

A very special thank you to Prof. Dr. András Székács at the Hungarian University of Agriculture and Life Sciences

Check out Carey Gillam’s books here — https://ve42.co/Gillam
Check out Bart Elmore’s book here — https://ve42.co/SeedMoney

The opening music track “Another Offering” is from https://audiomachine.com/

▀▀▀
0:00 An Unusual Enemy
5:18 Monsanto’s Secret Poison Problem
11:17 Vietnam and Agent Orange
14:08 Roundup
19:31 How Monsanto Controls Seeds
26:06 The Crop Mafia
31:10 The Monsanto Papers
41:18 How dangerous is Roundup really?

▀▀▀
References:

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

Images & Video:

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

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

▀▀▀
Writers: Gregor Čavlović, Casper Mebius & Derek Muller
Producer & Director: Gregor Čavlović
Editor: Spencer Wright & Peter Nelson
Camera Operators: Gregor Čavlović, Henry van Dyck & Casper Mebius
Animators: Allama Nandi, Andrew Neet, Emma Wright, Fabio Albertelli, Ivy Tello, Rokas Viksraitis & Saif Javed
Illustrators: Jakub Misiek, Maria Gusakovich, Veronika Pasynkova, Grace Nemanic, Isaac McRee, Nataly Zhuk & Hollisstudioo
Assistant Editor: James Stuart & Fabio Albertelli
Assistant Writer: Daniel Leonard
Sound Designer: Pavle Peric
Researchers: Callum Cuttle, Aakash Singh Bagga, Gabe Strong & HyoJeong Choi
Thumbnail Designers: Abdallah Rabah, Ren Hurley & Ben Powell
Production Team: Josh Pitt, Nicola Griffiths, Matthew Cavanagh, Rob Beasley Spence & Zoe Heron
Executive Producers: Derek Muller & Casper Mebius
Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound

Are you smart enough to solve this Google interview question? Use code veritasium at https://incogni.com/veritasium to get an exclusive 60% off an annual Incogni plan.

A massive thank you to Dan Goldman, Jeff Aguilar, Daniel Soto and Georgia Tech’s Complex Rheology And Biomechanics Lab
We’re incredibly grateful to Carl Zimmer, Gayle McDowell, and Geoffrey West

Correction: Dan Goldman is a Professor of Physics not Biomechanics.

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

▀▀▀
0:00 Hard Google Interview Question
2:34 How do Geckos stick to walls?
5:58 Do physicists know the answer?
7:01 The Square-Cube Law
9:10 Tiny Superheroes
10:23 Simulating the problem
13:36 Adding Air Resistance
15:14 The End?
16:16 What would happen if you were shrunk?
17:39 What interviewers actually look for

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

▀▀▀
References:
William Poundstone (Jan 2012). Are You Smart Enough to Work at Google?. - https://ve42.co/smartenough
Giovanni Alfonso Borelli. Translated by Paul Maquet (1989). On the Movement of Animals. - https://ve42.co/borellianimals
In Head-Hunting, Big Data May Not Be Such a Big Deal. (Jun 2013) via New York Times - https://ve42.co/headhuntbigdata
Drag Forces. via Lumen Learning - https://ve42.co/dragforces
R. McN. Alexander (Feb 1995). Leg design and jumping technique for humans, other vertebrates and insects. The Royal Society Publishing - https://ve42.co/legdesignjump
Sharon B. Emerson (Sep 1978). Allometry and Jumping in Frogs: Helping the Twain to Meet. JSTOR - https://ve42.co/allometryfrogs
Jay J. Meyers, Anthony Herrel & James Birch (Jan 2002). Scaling of Morphology, Bite Force and Feeding Kinematics in an Iguanian and a Scleroglossan Lizard. Anthony Herrel - https://ve42.co/scalinglizard
Kirby TJ, McBride JM, Haines TL, Dayne AM. (Aug 2011). Relative Net Vertical Impulse Determines Jumping Performance. Journal of Applied Biomechanics - https://ve42.co/jumpperformance
Rasmussen Mette H. et al (Jul 2022). Evidence that gecko setae are coated with an ordered nanometre-thin lipid film. The Royal Society Publishing - https://ve42.co/geckosetae
Body Orientation During a Skydive. via Libre Texts Physics - https://ve42.co/skydivephysics

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Images & Video:
Here’s how many Google interviews it takes to hire a Googler. (Apr 2019) via CNBC Make It - https://ve42.co/googleinterviews
Google received 3.3 million job applications in 2019. (Jan 2020) via Axios - https://ve42.co/googleapplications
Here’s why you only have a 0.2% chance of getting hired at Google. (Oct 2014) via Quartz - https://ve42.co/hiredgoogle
Dear Reddit, my friend was asked this RIDICULOUS question in a job interview, what’s the best possible answer?. (2011) via Reddit - https://ve42.co/redditblender
Mark Rober. (May 2020) Backyard Squirrel Maze 1.0- Ninja Warrior Course https://www.youtube.com/watch?v=hFZFjoX2cGg
Cambridge University. (Feb 2010) Cambridge Ideas - Sticky Feet https://www.youtube.com/watch?v=hd5upt3IrWM
IV C. (Oct 2023)Incredible Shrinking Man (1957) Jack Arnold. The spider scene. El increíble hombre menguante. Araña https://www.youtube.com/watch?v=wJiJsbBBHpE&t=7s
Russ Amy. (Apr 2018) Honey I Shrunk the Kids 1989 1080p BluRay X264 AMIABLE mkv https://www.youtube.com/watch?v=byxGZ8cD7rk
R Sisters Gaming. (Feb 2022) It Takes Two - Destroyed by the Blender https://www.youtube.com/watch?v=QqrPufq2jP8
ClipsyBox. (May 2017) Hulk vs. Ant-Man - Coca-Cola: Coke Mini https://www.youtube.com/watch?v=sMkGwCw7iv8
El Gato. (June 2021) Squirrel has 44" vertical jump straight up to bird feeder! jumping https://www.youtube.com/watch?v=ethwLHw46JM
A-purpose . (Apr 2024). Who can jump bigger part #2 via Youtube - https://www.youtube.com/shorts/mJhf7wYNkYA

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

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Directed by Henry van Dyck
Written by Henry van Dyck
Edited by Peter Nelson and Nick Lear
Assistant Edited by James Stuart
Animated by Fabio Albertelli, Andrew Neet, Jakub Misiek and Emma Wright
Filmed by Henry van Dyck and Lukas Guderjahn
Additional Research by Emilia Gyles and Geeta Thakur
Produced by Derek Muller, Henry van Dyck, Zoe Heron, Rob Beasley Spence and Tori Brittain
Thumbnail contributions by Ben Powell, Ren Hurley and Henry van Dyck
Additional video/photos supplied by Getty Images and Storyblocks
Music from Epidemic Sound and Jonny Hyman

The Nobel Prize for physics in 2011 was awarded to Brian Schmidt, Adam Riess, and Saul Perlmutter for discovering that the universe is expanding at an accelerating rate. This finding was completely unexpected because it was thought that gravity should slow the expansion of the cosmos. The best current explanation of why the universe is accelerating is that there is some energy tied to empty space which pushes matter apart. This 'Dark Energy' makes up 73% of the universe but is very difficult to detect. Hopefully a better understanding of it will lead to a unification of our theories of gravitation and quantum mechanics.

Images courtesy of NASA - NASAimages.org

YES, THIS IS A REUPLOAD. The original was age-restricted and demonetized. To support the channel directly, you can buy Snatoms: https://ve42.co/snatoms1 https://ve42.co/amzn or support on Patreon: https://ve42.co/p

Fritz Haber is the scientist who arguably most transformed the world.
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A huge thanks to Dan Charles for writing a fantastic biography of Fritz Haber, for taking the time to talk to us about it, and providing valuable feedback. This video would not be what it is without his contributions. http://site.danielcharles.us https://ve42.co/Charles

Thanks to Tom de Prinse from Explosions and Fire for helping us with the chemistry of explosives. If you like explosions and/or fire, you will love his channel. https://www.youtube.com/c/ExplosionsFire2

Thanks to Michael Kuiper of CSIRO for the animation of the composition of air - https://www.youtube.com/watch?v=j9JvX58aRfg

Special thanks to Sonya Pemberton, Karl Kruszelnicki, Mary Dobbie, Olivia McRae, and the patreon supporters for giving us feedback on the earlier version of this video.

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References:

The primary reference used is Vaclav Smil’s excellent book, Enriching The Earth –
Smil, V. (2004). Enriching the earth: Fritz Haber, Carl Bosch, and the transformation of world food production. MIT press. – https://ve42.co/Smil

Mastermind: The Rise and Fall of Fritz Haber, the Nobel Laureate Who Launched the Age of Chemical Warfare, by Dan Charles – https://ve42.co/Charles

Stoltzenberg, D. (2004). Fritz Haber: Chemist, Nobel Laureate, German, Jew. Chemical Heritage Foundation. – https://ve42.co/Stoltzenberg

Postgate, J. R. (1982). The fundamentals of nitrogen fixation. CUP Archive. – https://ve42.co/postgate

Miles, A. G. (1992). Biological nitrogen fixation. – https://ve42.co/Miles

Friedrich, B., & Hoffmann, D. (2017). Clara Immerwahr: A life in the shadow of Fritz Haber. In One Hundred Years of Chemical Warfare: Research, Deployment, Consequences(pp. 45-67). Springer, Cham. – https://ve42.co/Friedrich2017

Da Silva, G. (2020). What is ammonium nitrate, the chemical that exploded in Beirut. Sci Am, 5. – https://ve42.co/Silva

Rodrigues, P., & Micael, J. (2021). The importance of guano birds to the Inca Empire and the first conservation measures implemented by humans. – https://ve42.co/rodrigues

Allison, F. E. (1957). Nitrogen and soil fertility. Soil, the, 85-94. – https://ve42.co/Allison

Crookes, W. (1898). Address of the President before the British Association for the Advancement of Science, Bristol, 1898. Science, 8(200), 561-575. – https://ve42.co/Crookes

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Special thanks to Patreon supporters: RayJ Johnson, Brian Busbee, Jerome Barakos M.D., Amadeo Bee, Julian Lee, Inconcision, TTST, Balkrishna Heroor, Chris LaClair, Avi Yashchin, John H. Austin, Jr., OnlineBookClub.org, Matthew Gonzalez, Eric Sexton, john kiehl, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Dumky, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Timothy O’Brien, Mac Malkawi, Michael Schneider, jim buckmaster, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

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Written by Petr Lebedev, Derek Muller, Felicity Nelson and Kovi Rose
Edited by Trenton Oliver
Animation by Jakub Mistek, Fabio Albertelli, Ivy Tello, Alex Drakoulis, Nils Ramses Kullack, and Charlie Davies
SFX by Shaun Clifford
Filmed by Petr Lebedev, Derek Muller and Raquel Nuno
Photo of nitrogen deficiency in rice from https://ve42.co/rice
Additional video/photos supplied by Getty Images
Music from Epidemic Sound: https://ve42.co/music

Which experts have real expertise? This video is sponsored by Brilliant. The first 200 people to sign up via https://brilliant.org/veritasium get 20% off a yearly subscription.

Thanks to https://www.chess24.com/ and Chessable for the clip of Magnus.

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Chase, W. G., & Simon, H. A. (1973). Perception in chess. Cognitive psychology, 4(1), 55-81. – https://ve42.co/chess1

Calderwood, R., Klein, G. A., & Crandall, B. W. (1988). Time pressure, skill, and move quality in chess. The American Journal of Psychology, 481-493. – https://ve42.co/chess2

Hogarth, R. M., Lejarraga, T., & Soyer, E. (2015). The two settings of kind and wicked learning environments. Current Directions in Psychological Science, 24(5), 379-385. – https://ve42.co/Hogarth

Ægisdóttir, S., White, M. J., Spengler, P. M., Maugherman, A. S., Anderson, L. A., Cook, R. S., ... & Rush, J. D. (2006). The meta-analysis of clinical judgment project: Fifty-six years of accumulated research on clinical versus statistical prediction. The Counseling Psychologist, 34(3), 341-382. – https://ve42.co/anderson1

Ericsson, K. A. (2015). Acquisition and maintenance of medical expertise: a perspective from the expert-performance approach with deliberate practice. Academic Medicine, 90(11), 1471-1486. – https://ve42.co/anderson2

Goldberg, S. B., Rousmaniere, T., Miller, S. D., Whipple, J., Nielsen, S. L., Hoyt, W. T., & Wampold, B. E. (2016). Do psychotherapists improve with time and experience? A longitudinal analysis of outcomes in a clinical setting. Journal of Counseling Psychology, 63(1), 1. – https://ve42.co/goldberg1

Ericsson, K. A., Krampe, R. T., & Tesch-Römer, C. (1993). The role of deliberate practice in the acquisition of expert performance. Psychological Review, 100(3), 363. – https://ve42.co/anderson3

Egan, D. E., & Schwartz, B. J. (1979). Chunking in recall of symbolic drawings. Memory & Cognition, 7(2), 149-158. – https://ve42.co/chunking1

Tetlock, P. E. (2017). Expert political judgment. In Expert Political Judgment. Princeton University Press. – https://ve42.co/Tetlock

Melton, R. S. (1952). A comparison of clinical and actuarial methods of prediction with an assessment of the relative accuracy of different clinicians. Unpublished Ph.D. thesis, University of Minnesota.

Meehl, E. P. (1954). Clinical versus Statistical Prediction: A Theoretical Analysis and a Review of the Evidence. University of Minnesota Press. – https://ve42.co/Meehl1954

Kahneman, D. (2011). Thinking, fast and slow. Farrar, Straus and Giroux. – https://ve42.co/Kahneman

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Special thanks to Patreon supporters: RayJ Johnson, Brian Busbee, Jerome Barakos M.D., Amadeo Bee, Julian Lee, Inconcision, TTST, Balkrishna Heroor, Chris LaClair, Avi Yashchin, John H. Austin, Jr., OnlineBookClub.org, Matthew Gonzalez, Eric Sexton, john kiehl, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Dumky, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Timothy O’Brien, Mac Malkawi, Michael Schneider, jim buckmaster, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

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Written by Derek Muller and Petr Lebedev
Animation by Ivy Tello and Fabio Albertelli
Filmed by Derek Muller and Raquel Nuno
Additional video/photos supplied by Getty Images
Music from Epidemic Sound (https://ve42.co/music)
Produced by Derek Muller, Petr Lebedev, and Emily Zhang

Some months a go I filmed a slinky falling in slow motion. Now I have interviewed the public about what they expect to happen for ABC TV's Catalyst program and this is the result.

Is punishment or reward more effective as feedback? Do new medical treatments really work? What about streaks in sport? Without considering regression to the mean, we are prone to making significant errors.

Check out Audible.com: http://bit.ly/ZJ5Q6z
Filmed at Perimeter Institute: http://pitp.ca

Is punishment or reward more effective for helping people learn. A lot of people would say different incentives motivate different people, or in different circumstances, but in psychology there is a sizable body of evidence that in order to learn skills, positive feedback is more effective. This fining has been verified not just with humans, but also with other species.

It was strange then that after Daniel Kahneman discussed this research with Israeli fighter pilot instructors that he was met with resistance. They found the opposite was true: when they reprimanded a cadet for performing poorly, he invariably improved, but if they praised a cadet for an excellent performance, the next attempt was not as good. In order to solve this apparent contradiction we first need to understand regression to the mean.

Teacher study: http://bit.ly/1h8puVT
Rugby player study: http://bit.ly/1aNSrBI

Cell biology gives clues to why we age and lobsters don't.
I made another video! The future of energy: http://bit.ly/1MAiJKm
Check out Breakthrough, Sundays at 9/8c on Nat Geo with GE #ad

Animations are from Emmy-winning film 'Immortal', reproduced here courtesy of December Media and Genepool Productions (previously Pemberton Films)

Check out Immortal here: http://bit.ly/VeImmortal

Find out more about telomeres and telomerase here: http://bit.ly/WakeTelomeres

Special thanks to Dr. Fiona Ginty, Principal Scientist in the Life Sciences and Molecular Diagnostics Group at GE. Her research focuses on imaging different proteins within the cell. It's both a very powerful technique and it's beautiful.

Filmed by Raquel Nuno and Vasilios Sfinarolakis
Aging makeup by Heather Grippaldi: http://bit.ly/1Xebikh
Music by Kevin MacLeod, www.incompetech.com "Past the Edge" and "Lightless Dawn"

Chaos theory means deterministic systems can be unpredictable. Thanks to LastPass for sponsoring this video. Click here to start using LastPass: https://ve42.co/VeLP
Animations by Prof. Robert Ghrist: https://ve42.co/Ghrist

Want to know more about chaos theory and non-linear dynamical systems? Check out: https://ve42.co/chaos-math

Butterfly footage courtesy of Phil Torres and The Jungle Diaries: https://ve42.co/monarch
Solar system, 3-body and printout animations by Jonny Hyman
Some animations made with Universe Sandbox: https://universesandbox.com/
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 https://epidemicsound.com "The Longest Rest" "A Sound Foundation" "Seaweed"