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

▀▀▀
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

▀▀▀
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

▀▀▀
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

What is the optimal strategy for bowling? #science #veritasium #physics #bowling

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

▀▀▀
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

▀▀▀
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

▀▀▀
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

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.

▀▀▀
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 Bean, Geeta Thakur, and Emili Gyles
Produced by Casper Mebius, Derek Muller, Emily Zhang, Gregor Čavlović, Rob Beasley Spence, Tori Brittain, Gabe Bean, 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 invention that's super sticky, a little picky, and easy to unstick only if you know the trick!
Get a little smarter every day with Brilliant. Visit https://brilliant.org/veritasium for a 30-day free trial and 20% off your annual premium subscription.

A heartfelt thank you to Dr. Allison Christy and Dr. John Bobo for their invaluable expertise, fresh perspectives, and explanations.
Thank you to Emily Von Stein and Chris Masahiro at Aron Alpha, Dr. Chantelle Champagne, and Dr. Rohit Gupta for their time and contributions to the initial research that laid the groundwork for this project.

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

ANIMATION CORRECTION:
At 4:52, the negative charge should be drawn on the carbon at the end of the chain, not on the second to last carbon. This also holds during the polymerization process (5:15), where the negative charge should move right to the end of the chain.

▀▀▀
0:00 The Invention of Super Glue
2:43 How Does Super Glue Work?
5:38 How To Get Superglue Off Your Skin
8:33 Why Is Super Glue So Strong?
12:00 Why Doesn’t Super Glue Work on plastic?
13:45 Mixing Super Glue and Baking Soda
15:30 Using Super Glue Underwater
15:59 Super Glue On Wounds
19:47 A Solution To Microplastics?

▀▀▀
References and Credits:


Dr. Harry Coover Jr. (Nov 2023) via Sutori - https://ve42.co/sutori
Allison Christy, Closed-loop recyclable plastics from poly(ethyl cyanoacrylate) - https://www.science.org/doi/10.1126/sciadv.adg2295
About Cyanoacrylate Adhesives. via Permabond - https://ve42.co/permab
Kodak Eastman In Wikipedia - https://ve42.co/kodakw
Harry Coover and the Invention of Super Glue. (Mar 2022) via SciHi Blog - https://ve42.co/scihio
Humphrey Sam Samuel (May 2024). Cyanoacrylate Chemistry and Polymerization Mechanisms. - https://ve42.co/pcbioc
Radical polymerization.. In Wikipedia - https://ve42.co/wikira
Overview of materials for Cyanoacrylate Adhesive. via MATWEBb - https://ve42.co/matweb
United States Patent Office: US2776232. (Jan 1957) via US patent office - https://ve42.co/patentb
Medical Grade Cyanoacrylate Adhesive Market Size Growth Report. (Nov 2024) via Linkedin - https://ve42.co/linkpu
Science Channel. (Dec 2017). Think Super Glue Can Lift A Pickup Truck? via Youtube - https://ve42.co/ytbpee
Loctite & Teroson UK. (Apr 2023). Learn How Loctite SF 7452 Can Accelerate Bonding When using Loctite 454 via Youtube - https://ve42.co/loctiteg

Image and Video Credits
LOCTITE® North America. (May 2017). Loctite 4902FL Highly Flexible Cyanoacrylate via Youtube - https://ve42.co/loctitef
The Gorilla Glue Company. (May 2021). How To Use Gorilla Super Glue via Youtube - https://ve42.co/gluehowt
Flex Seal. (Nov 2022). Flex Super Glue Commercial - The Flex Seal Family of Products via Youtube - https://ve42.co/flexglue
ewjxn. (Nov 2020). 1984 Instant Krazy Glue Strong enough to hold this woman TV Commercial.mp4 via Youtube - https://ve42.co/krazyglue
tvdays. (Nov 2007). ELMERS GLUE 1960.mp4 via Youtube - https://ve42.co/elmer
Aron Alpha Industrial Krazy Glue. (Feb 2024). The Leader in High Performance Instant Adhesives via Youtube - https://ve42.co/aronalpha
How researchers turned superglue into a cheap plastic alternative by via fastcompany - https://ve42.co/superplastic
Woman Mistakenly Uses Glue Instead Of Eye Drops by via CBS News - https://ve42.co/eyegludd

Further References: https://ve42.co/refsuperglue


▀▀▀
Special thanks to our patrons for sticking around!

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, 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, TTST, Tj Steyn, Ubiquity Ventures, wolfee

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

Live on Patreon now is an exclusive unseen interview with Chantelle Champagne https://www.patreon.com/posts/121045719

▀▀▀
Directed by Sulli Yost
Written by Sulli Yost and Derek Muller
Edited by Peter Nelson
Assistant Editor - James Stuart
Illustrated by Jakub Misiek and Caine Esperanza
Animated by Emma Wright, Andrew Neet and Fabio Albertelli
Filmed and demos done by Sulli Yost, Derek Muller and Wylie Overstreet
Additional research by Geeta Thakur
Produced by Sulli Yost, Derek Muller, Rob Beasley Spence and Tori Brittain
Thumbnail contributions by Ren Hurley, Peter Sheppard, Ben Powell
Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound and Jonny Hyman

What happens when you shrink robots down to the size of insects? Let’s explore the mind-bending physics behind their superpowers! Engineers get Onshape Professional free up to 6 months: go to https://www.onshape.pro/veritasium to create CAD models and bring your ideas to life.

▀▀▀
00:00 The Problem Of Surface Tension
3:16 How Does A Bee Fly?
7:08 What Powers Something So Small?
8:16 Tiny Muscles
10:36 Pogo Sticks On Mars
11:27 Mini Search Parties
13:29 Swarms Of Spybots
15:55 Penny Sized Combustion Engines
18:40 Science For Science’s Sake

▀▀▀
A massive thank you to Kevin Chen and the Soft and Micro Robotics Laboratory at MIT.
for hosting us and showcasing their incredible robots. Do check out their paper Acrobatics at Insect Scale: https://www.science.org/doi/10.1126/scirobotics.adp4256
We’re incredibly grateful to Mechanical Engineering at Cornell and the Harvard Microrobotics Lab for their groundbreaking work that informed much of what we’ve shared here.
Special thanks to Pakpong Chirarattananon and Cameron Aubin for their expertise and insights into mini-robot science.

CORRECTION: The scale bar at 18:19 is wrong. It should be 2cm, not 2mm. Thanks @nicolaszaugg5825 for pointing it out.

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

References: https://ve42.co/botsrefs

Video and Image Credits:
Giving bug-like, flying robots a boost by MIT via YouTube - https://ve42.co/FlyingRobots
Leading edge vortex stably attached near the base of a freely flying maple seed Acer pseudo-platanus by Francis Villatoro via YouTube - https://ve42.co/VortexStab
NASA Mars Helicopter Ingenuity Animations by JPLRaw via YouTube - https://ve42.co/IngenuityAnim
Rolls-Royce | SWARM Robots by Rolls Royce via YouTube - https://ve42.co/SWARMRobots
Robot Rescue: Behind The Technology Deployed For Disaster Relief | by NBC News via YouTube - https://ve42.co/RobotRescue
Call to Service: The Final Rescue of 9/11 by 5.11 Tactical via YouTube - https://ve42.co/CallToService
Colony Collapse: The Mystery of the Missing Bees | Retro Report | by NYT via YouTube - https://ve42.co/ColonyCollapse

▀▀▀
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, 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

▀▀▀
Directed by Henry van Dyck
Written by Henry van Dyck
Edited by Nick Lear and Trenton Oliver
Animated by Fabio Albertelli, Jakub Misiek, Emma Wright and Ivy Tello
Filmed by Henry van Dyck, Petr Lebedev and Michael Cimpher
Additional Research by Geeta Thakur and Gabe Bean
Produced by Derek Muller, Henry van Dyck, Rob Beasley Spence, and Tori Brittain
Thumbnail contributions by Ben Powell, Peter Sheppard, Ren Hurley and Henry van Dyck
Additional video/photos supplied by Getty Images and Story blocks
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/

▀▀▀
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?

▀▀▀
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.

▀▀▀
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

LSD-fiend, surfer, maverick — Kary Mullis might be the weirdest person ever to win the Nobel Prize. Get a little smarter every day with Brilliant. Visit https://brilliant.org/veritasium to get 20% off your annual premium subscription.

A massive thank you to Tom White, Hudson Freeze, and Henry Erlich for their time and expertise on the subject.

A huge thank you to Eleni Kleanthous, Jan Novoselec, Kieran Sparkes, Andrew Garcia, and UCSD’s Pride Lab for reviewing the science.

For great coverage of the PCR story, check out ‘Making PCR’ by Paul Rabinow - https://ve42.co/Rabinow1996

For exclusive behind-the-scenes content on the making of this video, join us on Patreon: https://www.patreon.com/posts/119438561

00:00 DNA under a microscope
01:17 Kary Mullis at Berkeley
02:50 Cetus and early biotech
04:16 How to detect sickle cell anemia
09:12 Kary Mullis at Cetus
10:39 Infinite DNA glitch explained
15:29 Kary Mullis struggles
18:10 Thermus Aquaticus to the rescue
23:53 Going public
26:59 The quirky genius, Kary Mullis

▀▀▀
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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, 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, 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

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References:
Mullis, K. (1968). Cosmological Significance of Time Reversal. Nature - https://ve42.co/Mullis1968
Mullis, K. (1997). Dancing Naked in the Mind Field. Vintage - https://ve42.co/Mullis1997
McDonald, C. (2019). Intolerable Genius. Cal Alumni Association - https://ve42.co/McDonald2019
Conner, B. J. et al. (1983). Detection of sickle cell beta S-globin allele by hybridization with synthetic oligonucleotides. Proceedings of the National Academy of Sciences - https://ve42.co/Conner1983
Human Beta-globin gene via UniProt - https://ve42.co/BetaGlobin
Saiki, R. K. et al. (1985). Enzymatic Amplification of β-Globin Genomic Sequences and Restriction Site Analysis for Diagnosis of Sickle Cell Anemia. Science - https://ve42.co/Saiki1985
Mullis, K. B. (1990). The Unusual Origin of the Polymerase Chain Reaction. Scientific American - https://ve42.co/Mullis1990
Kary B. Mullis via The Nobel Prize - https://ve42.co/Nobel1993
Restriction Enzymes via The Nobel Prize - https://ve42.co/Nobel1978
Saiki, R. K. et al. (1988). Primer-Directed Enzymatic Amplification of DNA with a Thermostable DNA Polymerase. Science - https://ve42.co/Saiki1988
Smith, T. C. (2024). HIV Denial in the COVID Era. AIDS and Behavior. - https://ve42.co/Smith2024
Mullis, K. B., Faloona, F. A. (1987). Specific synthesis of DNA in vitro via a polymerase-catalyzed chain reaction. Methods in Enzymology - https://ve42.co/Mullis1987
Dr. Kary Mullis about LSD via RadioIciMaintenant Rim - https://ve42.co/MullisLSD
Brock, T. D., & Freeze, H. (1969). Thermus aquaticus gen. n. and sp. n., a Nonsporulating Extreme Thermophile. Journal of Bacteriology - https://ve42.co/Brock1969
Rediscovering Yellowstone via UW-Madison - https://ve42.co/Madison2017
Presidential Aids Advisory Panel Report via gov.za - https://ve42.co/Mbeki2001
Nattrass, N. (2008). AIDS and the Scientific Governance of Medicine in Post-Apartheid South Africa. African Affairs - https://ve42.co/Nattrass2008
Chigwedere, P. et al. (2008). Estimating the Lost Benefits of Antiretroviral Drug Use in South Africa. JAIDS Journal of Acquired Immune Deficiency Syndromes - https://ve42.co/Chigwedere2008

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

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Directed by Gregor Čavlović and Latif Nasser
Written by Gregor Čavlović, Latif Nasser, and Derek Muller
Edited by Peter Nelson
Animated by Ivy Tello, Emma Wright, Fabio Albertelli, Andrew Neet, and Alex Drakoulis
Illustrated by Emma Wright, Maria Gusakovich, and Jakub Misiek,
Filmed by Derek Muller, Alex Gorosh, and Gregor Čavlović
Additional research by Geeta Thakur and Gabriel Bean
Produced by Derek Muller, Latif Nasser, Gregor Čavlović, Rob Beasley Spence, Emily Lazard, Tori Brittain, James Horsley, Luke Lewis, Matthew Cavanagh, Barbara Abraul, Henry Van Dyck, Petr Lebedev, and Casper Mebius

Thumbnail contributions by Ben Powell, Ren Hurley, Peter Sheppard, Maria Gusakovich, Emma Wright, Jakub Misiek, and Tommy Steven

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

This musical instrument is 400,000+ years old and still growing. 🌏 Get exclusive NordVPN deal here ➵ https://NordVPN.com/veritasium It’s risk free with Nord’s 30 day money-back guarantee!✌

Special thanks to Luray Caverns - https://luraycaverns.com/
A massive thanks to Rob Scallon, please check out his YouTube channel -- he posts some incredible videos, like this one -- https://youtu.be/cVqqNigImtU?si=otDDVq_00xB3qCy6

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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

▀▀▀
Directed by Petr Lebedev
Written by Petr Lebedev
Edited by Jack Saxon
Animated by Jakub Misiek, Fabio Albertelli and Andrew Neet
Filmed by Henry van Dyck, Sumeet Kulkarni and Petr Lebedev
Additional research by Gabe Bean and Geeta Thakur
Produced by Petr Lebedev, Derek Muller, Emily Zhang, 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

When the demonstration hits your eye and it explains the value of pi, that’s Newton! #veritasium #science #physics