Your genetic code is probably already in a database, without you ever giving a sample or permission. This video is sponsored by Brilliant. The first 200 people to sign up via https://brilliant.org/veritasium get 20% off a yearly subscription.

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A huge thanks to Paul Holes, Billy Jensen, Brett Williams, Dr Connie Bormans and Dr Doc Edge for being part of this video. Thanks to Verogen and Family Tree DNA for giving me access to film.

Thanks to Sonya Pemberton, Joe Hanson, Raquel Nuno, CGP Grey, and numerous Patreon supporters for helpful feedback on an earlier version of this video.

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References:
Phillips, C. (2018). The Golden State Killer investigation and the nascent field of forensic genealogy. Forensic Science International: Genetics, 36, 186-188. -- https://ve42.co/Phillips2018

Guerrini, C. J., Robinson, J. O., Petersen, D., & McGuire, A. L. (2018). Should police have access to genetic genealogy databases? Capturing the Golden State Killer and other criminals using a controversial new forensic technique. PLoS biology, 16(10), e2006906. -- https://ve42.co/Guerrini

Ram, N., Guerrini, C. J., & McGuire, A. L. (2018). Genealogy databases and the future of criminal investigation. Science, 360(6393), 1078-1079. -- https://ve42.co/Ram2019

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Special thanks to Patreon supporters: Andrew, Diffbot, Micah Mangione, MJP, Gnare, Nick DiCandilo, Dave Kircher, Edward Larsen, Burt Humburg, Blake Byers, Dumky, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Mac Malkawi, Michael Schneider, Big Badaboom, Ludovic Robillard, Jim buckmaster, fanime96, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Marinus Kuivenhoven, Alfred Wallace, Clayton Greenwell, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal


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Executive Producer: Derek Muller
Writer: Derek Muller
Animators: Ivy Tello, Another Angle 3D Visuals
SFX: Shaun Clifford
Camerapeople: Derek Muller, Raquel Nuno, Shirley Dutoit, Emily Zhang
Editor: Derek Muller
Producers: Derek Muller, Casey Rentz, Petr Lebedev, Emily Zhang
Additional video supplied by Getty Images
Music from Epidemic Sound https://epidemicsound.com
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Many videos on YouTube show water freezing almost instantaneously. This video shows you how to replicate the experiment and it explains how the phenomenon works. Molecular illustrations are courtesy of:
PhET Interactive Simulations
University of Colorado
http://phet.colorado.edu.

We experimented to see how much pain our volunteers could handle. Go to https://headspace-web.app.link/e/vstm to try Headspace for free using the code VERITASIUM

Studies on Headspace - https://ve42.co/Headspace

A massive thank you to Rayner Moss for recreating the experiment equipment and making this shoot happen.

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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, 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., John H. Austin, Jr., John Kiehl, Josh Hibschman, Juan Benet, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Max Paladino, Meekay, Meg Noah, Michael Krugman, Name, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Stephen Wilcox, Tj Steyn, Toni, TTST, Ubiquity Ventures, 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

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References:
Kahneman, D. et al. (1993). When More Pain Is Preferred to Less: Adding a Better End. Psychological Science - https://ve42.co/Kahneman1993
Kahneman, D. (2011). Thinking, fast and slow. Farrar, Straus and Giroux - https://ve42.co/FastAndSlow
Fredrickson, B. L., Kahneman, D. (1993). Duration neglect in retrospective evaluations of affective episodes. Journal of personality and social psychology - https://ve42.co/Fredrickson1993
Kahneman, D., Tversky, A. (1972). Subjective probability: A judgment of representativeness. Cognitive Psychology - https://ve42.co/Kahneman1972
Diener, E. et al. (2001). End Effects of Rated Life Quality: The James Dean Effect. Psychological Science - https://ve42.co/Deiner2001
Redelmeier, D. A. et al. (2003). Memories of colonoscopy: a randomized trial. Pain - https://ve42.co/Redelmeier2003
Kemp, S. et al. (2008). A test of the peak-end rule with extended autobiographical events. Memory & Cognition - https://ve42.co/Kemp2008

Images & Video:
Daniel Kahneman via UNSW - https://ve42.co/ImgKahneman
Barbara Fredrickson via UNC - https://ve42.co/ImgFredrickson
Stephen Gould via achievement.org - https://ve42.co/ImgGould
Amos Tversky via LGT - https://ve42.co/ImgTversky

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Directed by Petr Lebedev
Written by Petr Lebedev and Derek Muller
Edited by Peter Nelson
Animated by Fabio Albertelli and Ivy Tello
Illustrated by Jakub Misiek
Filmed by Derek Muller and Bernard Lau
Produced by Petr Lebedev, Derek Muller, Rob Beasley Spence, Owen Maher, David Szasz, Emily Taylor, Gregor Čavlović and Alistair Dann

Thumbnail contributions by Ren Hurley and Peter Sheppard

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

Myths and misconceptions about planes. Go to https://groundnews.com/Ver to see through media misconceptions and get all sides of every story. Subscribe to save 40% off unlimited access through our link.

If you enjoyed this video and want to go deeper, you'll find extended interviews, deleted scenes, and some of our early thumbnail concepts over on Patreon https://www.patreon.com/posts/....patreon-what-1120393

A massive thank you to Petter Hörnfeldt for his expertise and time. Check out @MentourPilot.

A huge thank you to Baz Collins, Nick Woods, Val Bukmanis, and everyone at the Queensland Air Museum for hosting us and making this shoot possible - https://ve42.co/QLDAir

A special thanks to Roddy McNamee for helping out with the script - https://ve42.co/RMcN

A big thank you to Emily Zhang, Petr Lebedev, and Casper Mebius for their help and guidance!

00:00 Can plane doors be opened mid-flight?
00:28 How high do planes fly?
02:31 How do jet engines work?
04:43 Airplanes before cabin pressurization
05:34 Why don’t pressurized planes need door locks?
07:07 Do people fart more in planes?
07:57 The story of Aloha Airlines Flight 243
09:21 The story of Asiana Airlines Flight AA8124
09:57 Is “airplane mode” on phones real?
13:53 Why does airplane food taste bad?
15:07 Why do people drink tomato juice on planes?
16:15 How safe is air travel?

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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, 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

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

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References:
Pilot’s Handbook of Aeronautical Knowledge via the FAA - https://ve42.co/LiftandDragEqs
Compressor efficiency by Roddy McNamee - https://ve42.co/Compressor
Garrido, E. et. al. (2019). Breathless and dying on Mount Everest. The Lancet Respiratory Medicine - https://ve42.co/Everest3min
Cabin Pressurization via Wikipedia - https://ve42.co/CabinPressure
B737 door specifications by Chris Brady - https://ve42.co/737door
Aloha Airlines 243 Accident Report by the NTSB - https://ve42.co/AlohaAirline
Boeing 737-297 Specifications via the FAA - https://ve42.co/AlohaCycles
(PED) Aviation Rulemaking Committee via the FAA - https://ve42.co/AirplaneMode
Ritchie, C. (1996). Potential Liability from Electromagnetic Interference. Journal of Air Law and Commerce - https://ve42.co/Ritchie1996
FAA restrictions via eCFR - https://ve42.co/FAArules
Is Phone Interference Phony? via Wired - https://ve42.co/FCCTesting
Sabatini N. (2005). Statement before the Subcommittee of Aviation. U.S. Department of Transportation - https://ve42.co/FCCquote
EU rules on Airplane Mode via euronews.com - https://ve42.co/EUAPM
Mayer, F. et al. (2022). Indoor Air Quality in Commercial Air Transportation. Handbook of Indoor Air Quality - https://ve42.co/PlaneHumid
Burdack-Freitag, et al. (2010). Odor and taste perception in a simulated aircraft cabin. Journal of Consumer Protection and Food Safety. - https://ve42.co/SmellTaste

Images & Video:
Passenger Opens Emergency Exit via 10 News First - https://ve42.co/Jetstar
Airplane-Door OPENS Mid-flight! by Mentour Pilot - https://ve42.co/MentourAsia
A320 Door by Captain Time - https://ve42.co/A320Door
B737 Door by Abdulrahman Ismail - https://ve42.co/B737Door
The Miracle Landing Of Aloha Airlines Flight 243 by Wonder - https://ve42.co/Wonder243
Terrifying video shows Asiana flight door open in mid-air by National Post - https://ve42.co/PlaneDoorOpen
Faraday Cage by Radwell International - https://ve42.co/Faraday
Anatomy of the Inner Ear model by Annie Campbell, Now Medical Studios - https://ve42.co/EarAnatomy

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Directed by Gregor Čavlović and Derek Muller
Written by Gregor Čavlović, Derek Muller, Petr Lebedev, Emily Zhang, and Casper Mebius
Edited by Jack Saxon
Animated by Mike Radjabov, Fabio Albertelli, Ivy Tello, David Szakaly, and Jack Saxon Illustrated by Jakub Misiek
Filmed by Chase Brockett, Charles Clement, and Derek Muller
Additional research by Gabriel Strong
Produced by Derek Muller, Gregor Čavlović, Rob Beasley Spence, Tori Brittain, Owen Maher, Emily Lazard, Luke Lewis, Petr Lebedev, Emily Zhang, and Casper Mebius

Thumbnail contributions by Ren Hurley, Peter Sheppard, Mike Radjabov, and Igant Barbeci

Additional video/photos supplied by Getty Images and 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

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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

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

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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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Special thanks to our Patreon supporters:

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

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

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References: Ewald, W., & Sieg, W. (2013). David Hilbert's Lectures on the Foundations of Arithmetic and Logic 1917-1933. Springer Berlin Heidelberg. -- https://ve42.co/Ewald2013

Gamow, G. (1988). One, two, three--infinity: facts and speculations of science. Courier Corporation. -- https://ve42.co/Gamow1947

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

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

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Blimps and airships might be relics of the past, but could they help save the future? Head to https://www.odoo.com/r/veritasium to start building your own website for free.

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

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Thank you to Eli Dourado for letting us explore the argument he describes in his article: https://ve42.co/Dourado

A huge thank you to Dan Grossman and Nick Allman for their time, help, and expertise.

Also a massive thank you to those who helped us understand the world of modern airships, and provided valuable feedback - Prof. Barry Prentice, Gennadiy Verba, Prof.
Christoph Pflaum, Heather Roszczyk, Dr. Casey Handmer, Richard Van Trueren, & Thibault Proux.

We are also grateful for the collaboration of the companies who are working hard to make this comeback happen - Atlas LTA, Buoyant Aircraft Systems International, Hybrid Air Vehicles, LTA Research, & Flying Whales.


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References:

How Airships Could Overcome a Century of Failure, Bloomberg Originals via YouTube - https://ve42.co/AirshipsCoF

Why the Airship May Be the Future of Air Travel, Undecided with Matt Ferrell via YouTube - https://ve42.co/FutureAirships

Airship, Wikipedia - https://ve42.co/AirshipWiki

Handmer, C. (2020). A quick note on airships. Casey Handmer’s Blog - https://ve42.co/Handmer2020

UNCTAD (2020). Review of Maritime Transport 2020 - https://ve42.co/RMT2020

National Transportation Research Center (2023). Freight Analysis Framework Version 5 (FAF5) - https://ve42.co/FAF5

Hybrid Air Vehicles (2023). HAV - https://ve42.co/HAV

LTA Research (2023). Lighter Than Air (LTA) Research - https://ve42.co/LTAResearch

OceanSkyCruises (2023). North Pole Expedition - OceanSkyCruises - https://ve42.co/NPExpedition

Flying Whales (2023). Flying Whales - https://ve42.co/FlyingWhales

Buoyant Aircraft Systems International (2023). BASI - https://ve42.co/BASI

Atlas LTA (2023). Atlas Electric Airships | Atlas LTA Airships - https://ve42.co/AtlasLTA

Prentice, B. (2021). Hydrogen gas-fuelled airships could spur development in remote communities. The Conversation - https://ve42.co/HydrogenAirships

Grossman, D. (2009). The Hindenburg Disaster. Airships - https://ve42.co/Hindenburg1

Hindenburg Disaster, Wikipedia - https://ve42.co/HindenburgWiki

What happened to the Hindenburg?, Jared Owen via Youtube - https://ve42.co/Owen2019

National Museum of the U.S. Navy. USS Akron (ZRS-4) - https://ve42.co/USSAkron

USS Akron, Wikipedia - https://ve42.co/USSAkronWiki


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Special thanks to our Patreon supporters:
Adam Foreman, Amadeo Bee, Anton Ragin, Balkrishna Heroor, Benedikt Heinen, Bernard McGee, Bill Linder, Burt Humburg, Dave Kircher, Diffbot, Evgeny Skvortsov, Gnare, Jesse Brandsoy, John H. Austin, Jr., john kiehl, Josh Hibschman, Juan Benet, KeyWestr, Lee Redden, Marinus Kuivenhoven, Mario Bottion, MaxPal, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Stephen Wilcox, Tj Steyn, TTST, Ubiquity Ventures

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Written by Casper Mebius & Derek Muller
Directed by Casper Mebius
Edited by Jack Saxon
Filmed by Derek Muller, Jamie MacLeod, Han Evans, & Raquel Nuno
Animation by Mike Radjabov & Fabio Albertelli
Additional video/photos supplied by Getty Images, Pond5, & Envato Elements
Music from Epidemic Sound & Pond5
Produced by Casper Mebius, Derek Muller, & Han Evans


More footage & photos from:
Thermite Rail Welding video by dulevoz via YouTube - https://www.youtube.com/watch?v=rNjosF789X4

O’Rourke, T. (2016). Chronicle Covers: When the Hindenburg burst into flames. San Francisco Chronicle - https://ve42.co/Hindenburg2

Wind turbine blade transport video by DOLL Fahrzeugbau via YouTube - https://www.youtube.com/watch?v=5aPXuap0LZw

Wind turbine blade transport through mountains video by CGTN via Youtube - https://www.youtube.com/watch?v=9dtUrY8_1CM

Former Airship Hangar by Stefan Kühn - https://ve42.co/Aerium

For decades, the Sleeping Beauty Problem has divided people between two answers. Head to https://brilliant.org/veritasium to start your free 30-day trial, and the first 200 of you will get 20% off an annual premium subscription.

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Many thanks to Dr. Mike Titelbaum and Dr. Adam Elga for their insights into the problem.

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References:

Elga, A. (2000). Self-locating belief and the Sleeping Beauty problem. Analysis, 60(2), 143-147. - https://ve42.co/Elga2000

Lewis, D. (2001). Sleeping beauty: reply to Elga. Analysis, 61(3), 171-176. - https://ve42.co/Lewis2001

Winkler, P. (2017). The sleeping beauty controversy. The American Mathematical Monthly, 124(7), 579-587. - https://ve42.co/Winkler2017

Titelbaum, M. G. (2013). Ten reasons to care about the Sleeping Beauty problem. Philosophy Compass, 8(11), 1003-1017. - https://ve42.co/Titelbaum2013

Mutalik, P. (2016). Solution: ‘Sleeping Beauty’s Dilemma’, Quanta Magazine - https://ve42.co/MutalikQ2016

Rec.Puzzles - Some “Sleeping Beauty” Postings - https://ve42.co/SBRecPuzzles

The Sleeping Beauty Paradox, Statistics SE - https://ve42.co/SBPSSE

The Sleeping Beauty Problem, Reddit - https://ve42.co/SBPReddit

Sleeping Beauty paradox explained, GameFAQs - https://ve42.co/SBPGameFAQ

The Sleeping Beauty Problem, Physics Forums - https://ve42.co/SBPPhysicsForums

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Special thanks to our Patreon supporters:
Tj Steyn, Meg Noah, Bernard McGee, KeyWestr, Elliot Miller, Brian Busbee, Jerome Barakos, M.D., Amadeo Bee, TTST, Balkrishna Heroor, Chris LaClair, John H. Austin, Jr., Eric Sexton, john kiehl, Anton Ragin, Benedikt Heinen, Diffbot, Gnare, Dave Kircher, Burt Humburg, Blake Byers, Evgeny Skvortsov, Meekay, Bill Linder, Paul Peijzel, Josh Hibschman, Mac Malkawi, Mike Schneider, jim buckmaster, Juan Benet, Ubiquity Ventures, Richard Sundvall, Lee Redden, Stephen Wilcox, Marinus Kuivenhoven, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi.

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Written by Emily Zhang, Derek Muller, Tamar Lichter Blanks
Edited by Fabio Albertelli
Animation by Ivy Tello, Fabio Albertelli, Jakub Misiek
Additional video/photos supplied by Getty Images & Pond5
Music from Epidemic Sound
Thumbnail by Ignat Berbeci
Produced by Derek Muller, Petr Lebedev, Emily Zhang

Why do spikes form on ice cubes? Without them the world would be vastly different.
Awesome Jingle by Accent: http://bit.ly/AccentVe
Thanks to Prof. Stephen Morris from UofT: http://bit.ly/1GFANBE

Filmed in part by Martin Marek in Olomouc, Czech Republic

Time lapse of a growing ice spike by Lesley Hill, Russ Sampson and Edward Lozowski, with technical help by Kenny Lozowski.

Ice spike image by Dan and Lynn Wolaver: http://wolaver.org/log/09.11.29.htm

Concerned ice spike video by rocknut420: https://www.youtube.com/watch?v=GwM0we_t94c

Earth footage courtesy of NASA: https://www.youtube.com/watch?v=G4BPOEmugtM

Ice vase image by PgunnG: http://www.reddit.com/r/pics/c....omments/1voeqk/so_i_

Second ice vase image by A K Haart: http://akhaart.blogspot.com/20....15_01_01_archive.htm

What happens when single photons of light pass through a double slit and are detected by a photomultiplier tube? In 1801 Thomas Young seemed to settle a long-running debate about the nature of light with his double slit experiment. He demonstrated that light passing through two slits creates patterns like water waves, with the implication that it must be a wave phenomenon.

However, experimental results in the early 1900s found that light energy is not smoothly distributed as in a classical wave, rather it comes in discrete packets, called quanta and later photons. These are indivisible particles of light. So what would happen if individual photons passed through a double slit? Would they make a pattern like waves or like particles?

Why does energy disappear in General Relativity? 👉 Use code VERITASIUM to get 50% off your first monthly KiwiCo Crate! https://www.kiwico.com/VERITASIUM

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

▀▀▀
A huge thank you to Prof. Geraint Lewis, Prof. Melissa Franklin, Prof. David Kaiser, Elba Alonso-Monsalve, Richard Behiel, Prof. Leo Stein and Jakob Schwintenberg for their invaluable expertise and contributions to this video.

Special thanks to Alessandro from ScienceClic for his help on animations and input on the script. Check out his excellent video on Noether’s theorem here: https://www.youtube.com/watch?v=hF_uHfSoOGA

▀▀▀
0:00 What is symmetry?
4:25 Emmy Noether and Einstein
7:33 General Covariance
11:59 The Principle of Least Action
15:29 Noether’s First Theorem
18:24 The Continuity Equation
23:20 Escape from Germany
24:49 The Standard Model - Higgs and Quarks

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References:
MathHistory Biography - Emmy Amalie Noether via mathshistory.st-andrews.ac.uk - https://ve42.co/BioNoether
Bartlett, J. G. (2021). The Standard Cosmological Model and CMB Anisotropies. New Astron.Rev. 43 (1999) 83-109 - https://ve42.co/CosmoCMB
Kimberling, C. (1982). Emmy Noether, Greatest Woman Mathematician. Mathematics Teacher, March 1982, Volume 84, Number 3, pp. 246–249. - https://ve42.co/NoetherGreat
Blunck, A., et al. (2016). Mathematik und Gender. Verlag Franzbecker - https://ve42.co/MathGender
Evans, R. J. (1976). The Feminist movement in Germany, 1894-1933. Sage Publications - https://ve42.co/FeministGer
Without Emmy Noether, there would be a huge gap in mathematics and its understanding via www.mpg.de - https://ve42.co/NoetherGap
Dihedral group of order 6 via Wikipedia - https://ve42.co/Dihedral6
Emmy Noether University of Erlangen via Wikipedia - https://ve42.co/Erlangen
Timeline of women in mathematics via Wikipedia - https://ve42.co/WomenMath
Elizaveta Litvinova via Wikipedia - https://ve42.co/LitvinovaE
Sofya Kovalevskaya via Wikipedia - https://ve42.co/KovalevskayaS
Charlotte Scott via Wikipedia - https://ve42.co/ScottC
Cornelia Fabri via Wikipedia - https://ve42.co/FabriC
Emmy Noether, the renowned mathematician who taught 20 years of unpaid classes just because she was a woman via english.elpais.com - https://ve42.co/NoetherPay
Noether, E. (1908). Über die Bildung des Formensystems der ternären biquadratischen Form. Reimer - https://ve42.co/NDissert
Noether, E. (1983). Invariante Variationsprobleme. Gott.Nachr.1918:235-257,1918; Transp.Theory Statist.Phys.1:186-207,1971 - https://ve42.co/InvarProb
Noether, E. (2018). M. A. Tavel’s English translation of “Invariante Variationsprobleme”. arXiv - https://ve42.co/InvarProbEn
Byers, N. (1998). E. Noether’s Discovery of the Deep Connection Between Symmetries and Conservation Laws*. Mod.Phys.Lett. A14 (1999) 99-104 - https://ve42.co/SymCon
De Haro, S. (2021). Noether’s Theorems and Energy in General Relativity. Cambridge University Press, 2021 - https://ve42.co/EnergyGR
Rowe, D. E. (2019). Emmy Noether on Energy Conservation in General Relativity. arXiv - https://ve42.co/EnergyCon
Branding, K. (2005). A Note on General Relativity, Energy Conservation, and Noether’s Theorems. Springer - https://ve42.co/GRanEC

Additional References:
https://ve42.co/NoethersAdRefs

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Directed by Matthew Davies
Written by Matthew Davies, Casper Mebius, Derek Muller and Pablo Rovetto
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Illustrations by Jakub Misiek, Cainejan Esperanza, Tommy Stevens, Maria Gusakovich and Emma Wright
Additional research by Henry van Dyck, Gabe Strong and Darius Garewal
Produced by Matthew Davies, Casper Mebius, Derek Muller, Zoe Heron, Rob Beasley Spence and Tori Brittain

Thumbnail contributions by Jakub Misiek, Ren Hurley, Ben Powell and Peter Sheppard

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Music from Epidemic Sound

The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram.
Support Veritasium on Patreon: http://bit.ly/VePatreon

A kilogram isn't what it used to be. Literally. The original name for it was the 'grave', proposed in 1793 but it fell victim to the French Revolution like its creator, Lavoisier. So begins the tale of the most unusual SI unit. The kilogram is the only base unit with a prefix in its name, and the only one still defined by a physical artifact, the international prototype kilogram or IPK.

But the problem with this definition has long been apparent. The IPK doesn't seem to maintain its mass compared to 40 similar cylinders minted at the same time. The goal is therefore to eliminate the kilogram's dependence on a physical object. Two main approaches are being considered to achieve this end: the Avogadro Project and the Watt Balance.

The Avogadro project aims to redefine Avogadro's constant (currently defined by the kilogram -- the number of atoms in 12 g of carbon-12) and reverse the relationship so that the kilogram is precisely specified by Avogadro's constant. This method required creating the most perfect sphere on Earth. It is made out of a single crystal of silicon 28 atoms. By carefully measuring the diameter, the volume can be precisely specified. Since the atom spacing of silicon is well known, the number of atoms in a sphere can be accurately calculated. This allows for a very precise determination of Avogadro's constant.

Special thanks to Katie Green, Dr. David Farrant, the CSIRO, and the National Measurment Institute for their help. Thanks also to Nessy Hill for filming and reviewing earlier drafts of this video.

There is debate as to whether this is truly the roundest object ever created. The Gravity Probe-B rotors are also spherical with very low tolerances such that they may in fact be rounder.

Music by Kevin McLeod (incompetech.com) Decision, Danse Macabre, Scissors

This lab measures the tiniest forces in the universe. 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.

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Thanks to Rich Press and NIST for the great visit.
Thanks to Dr. Gordon Shaw for showing us around his lab and teaching us about measuring tiny forces.
You can check out all the cool work going on at NIST here: https://www.nist.gov/

▀▀▀
References:

Lee, J. (2016). Measuring Tiny Forces With Light. NIST. – https://ve42.co/Lee2016

Melcher, J., Stirling, J., Guzman, F., Pratt, J. & Shaw, G. (2014). A self-calibrating optomechanical force sensor with femtonewton resolution. Applied Physics Letters. – https://ve42.co/Melcher2014

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

Are all people on Earth really connected through just six steps?
There's much more science in this than I initially expected. It turns out ordered networks with a small degree of randomness become small-work networks. This is why your acquaintances turn out to be more important in job searches and finding new opportunities than close friends.

DON'T SEND ME AN EMAIL anymore...
1. Do not send it directly to me unless you know me.
2. Send the email to someone you have met IN PERSON and know on a first name basis AND THEY KNOW YOU.
3. Make the subject line 'Six Degrees of Veritasium'
4. Explain that you're trying to get this email to me and ask them to forward it on to me (only if they know me IRL) or someone they know who might know me.
5. If your email reaches me by Sept. 1, 2015 I will email you back and ask for your address so I can send you a postcard.

Animations in this video by The Lyosacks: https://www.youtube.com/user/TheLyosacks

There are some great books on this topic:
Duncan Watts, Six Degrees: The Science of a Connected Age
Albert-Laszlo Barabasi, Linkds: How Everything is Connected to Everything Else

And here are articles I referred to:
Milgram's small world experiment: http://www.uvm.edu/~pdodds/fil....es/papers/others/196
http://snap.stanford.edu/class..../cs224w-readings/mil

Granovetter, Strength of Weak Ties:
https://sociology.stanford.edu..../sites/default/files

New research shows chameleons actively tune nano-crystals to change their color.
For a 10-day free trial, check out http://lynda.com/veritasium
Chameleon research in Nature Communications: http://bit.ly/1FacHO2
"Photonic Crystals Cause Active Colour Change in Chameleons"

This research was carried out by Jérémie Teyssier, Suzanne V. Saenko, Dirk van der Marel & Michel C. Milinkovitch at the University of Geneva Department of Quantum Matter Physics and the Laboratory of Artificial and Natural Evolution (LANE)

Original videos of chameleons are here:
https://www.youtube.com/watch?v=YIRiCwHlUd8
https://www.youtube.com/watch?v=XdQvtP8EKrM
https://www.youtube.com/watch?v=YSH7EmXFMac
https://www.youtube.com/watch?v=egwueh6wj1E

Additional details available at: http://www.lanevol.org/LANE/ch....ameleon_colour_chang
For correspondence: Michel C. Milinkovitch, Laboratory of Artificial & Natural Evolution (LANE), Dept. of Genetics & Evolution, University of Geneva, Switzerland.

The melanin spreading out video is courtesy of Richard Wheeler:
https://www.youtube.com/watch?v=hL0USeWjTHQ
http://www.richardwheeler.net

Special thanks to:
Harry, Jo, Daniella and Raquel for helping me produce and film this video - it looks great thanks to you!

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

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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?

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References:

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

Images & Video:

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

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Writers: Gregor Čavlović, Casper Mebius & Derek Muller
Producer & Director: Gregor Čavlović
Editor: Spencer Wright & Peter Nelson
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Music from Epidemic Sound

Learned helplessness can prevent people from achieving their goals, something I've experienced first hand.
Check out Audible: http://bit.ly/AudibleVe
More walk and talk videos: http://bit.ly/2Veritasium

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

How to lead a happier, healthier and longer life. Check out our sponsor: https://betterhelp.com/veritasium to get matched with a professional therapist who will listen and help.

▀▀▀
A huge thanks to Prof. Robert Waldinger for all his help with this video.

To learn more about what makes for a good life, visit: https://the-good-life-book.com/ and https://www.youtube.com/watch?v=8KkKuTCFvzI&pp=ygUJd2FsZGluZ2Vy

A special thanks to Prof. Julianne Holt-Lunstad for her expert advice on the importance of social connections and the detrimental effects of loneliness and social isolation.

▀▀▀
Additional Videos:
Family Reacts to Winning CA$1 Million Lotto, NowThisNews via YouTube - https://ve42.co/CA1Lottery

Woman claims to be $1 billion Powerball winner, KTLA 5 via YouTube - https://ve42.co/1BilLottery

Old Lottery Winner Meets Young Lottery Winner | The Gap, LADbible TV via YouTube - https://ve42.co/LADBibleLottery

Why eyewitnesses get it wrong - Scott Fraser, TED-Ed via Youtube - https://ve42.co/TEDFraser

Surgeon General discusses health risks of loneliness and steps to help connect with others, PBS NewsHour via YouTube - https://ve42.co/PBS-SG

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References:
Waldinger, R., & Schulz, M. (2023). The Good Life: Lessons from the World's Longest Scientific Study of Happiness. Simon and Schuster.

Lindqvist et al. (2020). Long-run effects of lottery wealth on psychological well-being. The Review of Economic Studies. - https://ve42.co/Lindqvist2020

Wen et al. (2011). Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. The lancet. - https://ve42.co/Wen2011

Nocon et al. (2008). Association of physical activity with all-cause and cardiovascular mortality: a systematic review and meta-analysis. European Journal of Preventive Cardiology. - https://ve42.co/Nocon2008

Blondell et al. (2014). Does physical activity prevent cognitive decline and dementia?: A systematic review and meta-analysis of longitudinal studies. BMC public health. - https://ve42.co/Blondell2014

Office of the Surgeon General. (2023). Our Epidemic of Loneliness and Isolation: The US Surgeon General’s Advisory on the Healing Effects of Social Connection and Community. - https://ve42.co/LonelinessEpidemic

Holt-Lunstad et al. (2010). Social relationships and mortality risk: a meta-analytic review. PLoS medicine. - https://ve42.co/Holt-Lunstad2010

Valtorta et al. (2016). Loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and meta-analysis of longitudinal observational studies. Heart. -
https://ve42.co/Valtorta2016

Shovestul et al. (2020). Risk factors for loneliness: The high relative importance of age versus other factors. PloS one. - https://ve42.co/Shovestul2020

Donovan et al. (2017). Loneliness, depression and cognitive function in older US adults. International journal of geriatric psychiatry. - https://ve42.co/Donovan2017

Lara et al. (2019). Does loneliness contribute to mild cognitive impairment and dementia? A systematic review and meta-analysis of longitudinal studies. Ageing research reviews. - https://ve42.co/Lara2019

Holt-Lunstad et al. (2015). Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspectives on psychological science. - https://ve42.co/Holt-Lunstad2015

McIntyre et al. (2015). Compulsive Internet use and relations between social connectedness, and introversion. Computers in Human Behavior. - https://ve42.co/McIntyre2015

Kahneman & Deaton. (2010). High income improves evaluation of life but not emotional well-being. Proceedings of the national academy of sciences. - https://ve42.co/Kahneman2010

Killingsworth. (2021). Experienced well-being rises with income, even above $75,000 per year. Proceedings of the National Academy of Sciences. - https://ve42.co/Killingsworth2021

Killingsworth et al. (2023). Income and emotional well-being: A conflict resolved. Proceedings of the National Academy of Sciences. - https://ve42.co/Killingsworth2023

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

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Directed by Casper Mebius
Written by Casper Mebius, Petr Lebedev, and Derek Muller
Edited by Peter Nelson
Animated by Fabio Albertelli and Ivy Tello
Filmed by Derek Muller, Emily Zhang, and Zyan Treadwell
Produced by Casper Mebius, Petr Lebedev, Han Evans, and Derek Muller
Additional video/photos supplied by Getty Images and Storyblocks
Music from Epidemic Sound
Thumbnail by Ren Hurley

As a Canadian-Australian, I have always wondered why it is that Australia has so many venomous animals that can kill you while Canada has virtually none.
Subscribe to Veritasium - it's free! http://bit.ly/YSWpWm


But it's not just Australia - it seems like all beautiful, warm places are cursed with venomous native species. So I set out to find the truth: why have all these venomous species evolved in the world's best holiday destinations?

I asked chemists, visited the zoo, interviewed entomologists and snake experts. The answer I found was complicated:
1. The majority of venomous species are ectotherms, cold-blooded creatures whose internal temperatures are governed by their surroundings.
2. This means they have limited periods of activity - mainly while it's warm out, and can only exert short bursts of energy, so they are generally "sit and wait" predators. This may explain why they, more than mammals or birds, evolved venom.
3. It also explains why there are more of these species in warm climates. There are more of all species in warm climates, but this trend is especially pronounced for ectotherms.
4. So there are a greater number of venomous species in warm places, simply because there are more species in warm places. Cold climates still have venomous creatures, like the rattlesnakes of Canada and European vipers.
5. But history also has a role to play. In Australia, there were no snakes until 20 million years ago when a venomous sea snake from Asia encountered the land, sending venomous species to all corners of the continent. Later non-venomous arrivals have done well in the tropics but not as well in Australia's colder climates, so venomous types still dominate there. Hawaii has no venomous land snakes and nor does Jamaica.
6. The recent ice age also would have driven ectotherms from the northern parts of the Northern Hemisphere. This is why there are no snakes in Ireland, for example.

Special thanks to Prof. Rick Shine, Prof. Dieter Hochuli, Prof. Roger Lowe, Prof. Martyn Poliakoff and Taronga Zoo, especially Joe Haddock and Dean Purcell.

Cinematography by Charles Clement