How long is the coastline of Australia? One estimate is that it's about 12,500 km long. However the CIA world factbook puts the figure at more than double this, at over 25,700 km. How can there exist such different estimates for the same length of coastline? Well this is called the coastline paradox. Your estimate of how long the coastline is depends on the length of your measuring stick - the shorter the measuring stick the more detail you can capture and therefore the longer the coastline will be.

How lift actually works: http://www.youtube.com/watch?v=aFO4PBolwFg
More with Canadian Olympian Hunter Lowden: http://www.youtube.com/watch?v=6YVOPUkbu6g

How does a sailboat work? The standard idea is that the wind pushes the sails from behind, causing the boat to move forward. Although this technique is used at times, it is not the most efficient way to sail a boat (and it means the boat can never go faster than the wind). Lift is the key mechanism driving a boat forwards. As air flows over the sails, it moves faster over the outer side, creating lower pressure than on the inner side. This produces a force which is mostly to the side and a bit forwards. Lift on the centerboard pushes to the opposite side, cancelling the sideways force and adding a forward component of force to the boat.

numberphile http://bit.ly/numberphile
efit30 http://bit.ly/O4CMme
appchat http://bit.ly/NxAMlX
erikaanear http://bit.ly/MdyUzQ
whoisjimmy http://bit.ly/LtFzpW
minutephysics http://bit.ly/Muh6CC
1veritasium http://bit.ly/MrupzL

Boredom makes you more creative, altruistic, introspective, and helps with autobiographical planning.
This video was sponsored by LastPass: http://bit.ly/2wAsdUu

I feel like this video might come across as condescending but the person I'm really talking to is myself. Despite the fact that I know how useful it can be to be bored, I still find myself trying to fill every last moment with stimulus. Boredom is unpleasant - the open, unstructured thinking that can take place can also feel pointless. But now I'm made this video to remind myself how important boredom is so hopefully I'll make more time to be bored.

More resources:

The boredom leads people to shock themselves study:
Just Think: The challenges of the disengaged mind
https://wjh-www.harvard.edu/~d....tg/WILSON%20ET%20AL%

Boredom leads people to consider their future and set goals study:
Back to the future: Autobiographical planning and the functionality of mind-wandering
https://www.sciencedirect.com/....science/article/pii/

On boredom and altruism:
https://pdfs.semanticscholar.o....rg/ca72/0f959d3c9c31

Does boredom make us more creative?
https://www.tandfonline.com/do....i/abs/10.1080/104004

Amazing filming by Raquel Nuno

Music from http://epidemicsound.com "I Think I Was There" "Critical Thinking 2" "Wide Open" "Seaweed" "A Sound Foundation 1"

Music also by Kevin MacLeod http://incompetech.com "Fig Leaf Rag"

Why does time appear to speed up as we get older? Can we slow it down?
Thanks to the National Geographic Channel for sponsoring this video!
The new season of Brain Games starts Sunday, February 14th at 9/8c - http://po.st/90S7Ow

Brain Games is an Emmy-nominated TV series that explores the inner workings of the human mind through experiments and interactive games. Did you know it's estimated that you have more than a dozen senses in addition to the standard five? One of those is a sense of time or chronoception. Tune in to the new season of Brain Games to learn about all of your senses, and more, starting Sunday, February 14 at 9/8c

References:

Ageing and duration judgement:
http://bit.ly/1TRN0cr

Nerve conduction velocity slowing with age:
http://bit.ly/23Wq6oE

Experiments with rats suggest time perception is distributed across brain:
http://bit.ly/1T6IjdO

Time perception with repeated stimuli:
http://bit.ly/1TRNbo5

Energy usage in brain with age:
http://bit.ly/1nXliOU

Time perception in moments of fear / danger:
http://bit.ly/1RoK7Ps
http://1.usa.gov/1TRNa3w
http://bit.ly/1Q8tDvW

Attention’s relation to time perception and recollection of perceived time:
http://bit.ly/20odeD8
http://bit.ly/1TRNfEf

I am working on some big new projects I'm excited to share with you!

So this video is a little different from most of the others. The channel is an element of truth, after all, not an element of science. This is my truth. It may not be everyone's but that's ok too.

Clips included were from:
Chernobyl and Pripyat - drone shots from shooting Uranium
Obsidian dome, California
Panum Crater
El Capitan
The Pyramids of Giza
Toronto buildings
The Holocaust Memorial in Berlin
Abu Simbel temple at Aswan, Egypt
Sydney Harbour
Milky way time-lapse from the badlands of South Australia
Sunset over Warrnambool, Victoria
Big Bang animation courtesy of NASA
Sunrise over Bondi
Water off New Caledonia
Great white sharks in the Neptune Islands, South Australia
Crosswalk at Town Hall Sydney
EDUtubers at the YouTube EDU summit in San Francisco
Concert in Sydney
Jetpacking in Western Sydney
Vi's triangles at Perimeter Institute, Waterloo Canada
Aurora Borealis north of Fairbanks Alaska
Sagrada Familia, Barcelona, Spain
Hiking with MinutePhysics in Washington State

Music Licensed from cuesongs.com "The Secret Tower" by Nicholas O

How much would it take for you to risk $10?
Check out Audible: http://bit.ly/AudibleVe
Can you solve this? http://bit.ly/248Ve
Regression to the mean: http://bit.ly/VeRTTM

Help translate Veritasium videos into other languages: http://veritasium.subtitl.us

Psychological literature shows that we are more sensitive to small losses and than small gains, with most people valuing a loss around 1.5-2.5 times as much as a gain. This means that we often turn down reasonable opportunities for fear of the loss. However over the course of our lives we will be exposed to many risks and opportunities and this invariably means that taking every small reasonable bet will leave us better off than saying no to all of them.

NOTE: The video is not saying to accept every bet, only those with reasonable odds (preferably in your favour), and those which if you lose would not cause significant financial or other damage. In those cases it is wise to be loss averse!

Filmed by Adrian Tan

Thanks to Physics Girl for suggestions on previous versions of this video. https://www.youtube.com/physicswoman

We have just seen the first image of a black hole, the supermassive black hole in the galaxy M87 with a mass 6.5 billion times that of our sun. But what is that image really showing us?

This is an awesome paper on the topic by J.P. Luminet:
Image of a spherical black hole with thin accretion disk
Astronomy and Astrophysics, vol. 75, no. 1-2, May 1979, p. 228-235
https://ve42.co/luminet

Using my every day intuition I wondered: will we see the "shadow" of the black hole even if we're looking edge on at the accretion disk? The answer is yes because the black hole warps space-time, so even if we wouldn't normally be able to see the back of the accretion disk, we can in this case because its light is bent up and over the black hole. Similarly we can see light from the bottom of the back of the accretion disk because it's bent under the bottom of the black hole. Plus there are additional images from light that does a half turn around the black hole leading to the inner rings.

What about the black hole "shadow" itself? Well initially I thought it can't be an image of the event horizon because it's so much bigger (2.6 times bigger). But if you trace back the rays, you find that for every point in the shadow, there is a corresponding ray that traces back to the event horizon. So in fact from our one observing location, we see all sides of the event horizon simultaneously! In fact infinitely many of these images, accounting for the virtually infinite number of times a photon can orbit the black hole before falling in. The edge of the shadow is due to the photon sphere - the radius at which light goes around in closed orbits. If a light ray coming in at an oblique angle just skims the photon sphere and then travels on to our telescopes, that is the closest 'impact parameter' possible, and it occurs at sqrt(27)/2*r_s

Huge thanks to:
Prof. Geraint Lewis
University of Sydney https://ve42.co/gfl
Like him, I'm hoping (predicting?) we'll see some moving images of black holes tomorrow

Prof. Rana Adhikari
Caltech https://ve42.co/Rana

Riccardo Antonelli - for excellent images of black holes, simulations and ray-tracing code, check out:
https://ve42.co/rantonels

The Event Horizon Telescope Collaboration
Check out their resources and get your local link for the livestream here: https://ve42.co/EHT

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

Filming by Raquel Nuno
Animation by Maria Raykova

This tiny robot can jump higher than anything else in the world. This video is sponsored by Brilliant. The first 200 people to sign up via https://brilliant.org/veritasium get 20% off a yearly subscription.

Huge thanks to Dr. Elliot Hawkes and the rest of the group - Charles Xiao, Chris Keeley, Dr. Morgan Pope, and Dr. Günter Niemeyer - for having us at UCSB and showing us their high-flying jumper. This work was partially supported by an Early Career Faculty Grant from NASA’s Space Technology Research Grants Program.

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References:

Hawkes, E.W., Xiao, C., Peloquin, R., Keeley, C., Begley, M.R., Pope, M.T., & Niemeyer, G. (2022). Engineered jumpers overcome biological limits via work multiplication. Nature, 604, 657-661. – https://rdcu.be/cMePc
https://ve42.co/Hawkes2022
Fernandez, S. (2022). Hitting New Heights. The Current, UC Santa Barbara. – https://ve42.co/Fernandez2022
Bushwick, S. (2022). Record-Breaking Jumping Robot Can Leap a 10-Story Building. Engineering, Scientific American. – https://ve42.co/Bushwick2022
Mack, E. (2022). This Robot Can Leap Nine Stories in One Jump, Will Go Even Higher on Moon. Science, CNET. – https://ve42.co/Mack2022
Ashby, M. (2020). Materials Selection in Mechanical Design (4th edition). Elsevier.
Jumping robot leaps to record heights. Nature Video - https://ve42.co/NatureJumper
MultiMo-Bat Robot - https://ve42.co/MultiMoBat
Galago Jump - https://ve42.co/GalagoJump
Slingshot Spider - https://ve42.co/SlingshotSpider

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

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

As the universe expands, #expanding #space is said to "stretch" photons. But if it stretches photons, does it also stretch molecules, galaxies and you? A portion of this video was sponsored by Salesforce. Go to https://salesforce.com/veritasium to learn more.

Special thanks to Geraint Lewis - this video was based on his paper "On the relativity of redshifts"
https://arxiv.org/abs/1605.08634
Check out his YouTube channel: https://ve42.co/gfl and books: https://ve42.co/GFLbooks

References:
Expanding Space: the Root of all Evil?
Matthew J. Francis, Luke A. Barnes, J. Berian James, Geraint F. Lewis
https://arxiv.org/abs/0707.0380

Editing and VFX by Trenton Oliver
Thumbnail by Ignat Berbeci

Music from https://epidemicsound.com

#SMB #smallbiz #startups #SalesforceEssentials

High-energy rechargeable batteries seemed impossible, until we made them. Sponsored by CodeRabbit. Cut code review time and bugs in half. Try CodeRabbit at https://coderabbit.link/veritasium

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

▀▀▀
0:00 What’s inside a battery?
4:11 How does a battery work?
7:15 How did we increase battery power?
11:13 The first rechargeable lithium battery
13:29 The Tiny Needles That Kill Batteries
16:06 Goodenough? We can do better
20:07 The birth of the lithium-ion battery
27:10 Why do batteries explode?
29:31 Blowing up a battery

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A massive thank you to Dr Billy Wu, Dr Sam Cooper, Dr Derek Sui, Professor Magda Titirici, Dr Jingyu Feng, Dr Monica Marinescu, Li Ren Thow, Genlin Liu and Sam Riley; and to Professor Guillermo Rein, Dr Harry Mitchell, Hanna Berry, and Dr Nick Kalogeropoulos at Imperial College London for their invaluable contributions to this video. And a big thank you to Conrad Duncan for all his help in pulling everything together.

We’re incredibly grateful to Kurt Kelty and the team at General Motors for their time and expertise.

Thanks also go to Dr Yuzhang Li and Prof Jay Morton Turner for all their help on the project.

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References: https://ve42.co/RefsBatteries

Image References: https://ve42.co/ImgRefsBatt

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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, 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, Walter Flinn, wolfee

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Writers: Emilia Gyles, Casper Mebius, Gregor Čavlović & Derek Muller
Producer & Director: Emilia Gyles
Editor: Trenton Oliver
Camera Operators: Tas Underwood, Emilia Gyles, Gregor Čavlović & Derek Muller
Animators: Andrew Neet, Emma Wright, Fabio Albertelli, Mike Radjabov & Rokas Viksraitis
Illustrators: Jakub Misiek, Maria Gusakovich, Isaac McRee, Nataly Zhuk & Kaitlyn Chille
Assistant Editor: James Stuart
Researchers: HyoJeong Choi, Aakash Singh Bagga & Gabe Strong
Thumbnail Designers: Ren Hurley, Ben Powell & Abdallah Rabah
Production Team: Rob Beasley Spence & Josh Pitt
Executive Producers: Derek Muller & Casper Mebius
Additional video/photos supplied by Getty Images, Pond5
Music from Epidemic Sound

The sun has been producing light for about five billion years but where does all its energy come from? The most common idea is that the sun is burning gas - like a giant fireball in the sky. If this were true, the sun would have gone out long ago. So how is the sun actually fuelling itself? It is converting its own mass into energy. By combining protons (the nucleus of hydrogen) into helium, it squeezes some mass into energy - 4.3 billion kg per second. It is Einstein's famous E=mc^2 which gives us the quantitative relationship between mass and energy, where c is the speed of light.

Earth has been closer to Nuclear War more times than you’d think. Head over to
https://hensonshaving.com/veritasium and enter code 'Veritasium' for 100 free blades with the purchase of a razor. Make sure to add both the razor and the blades to your cart for the code to take effect.

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References:
List of Broken Arrows -- https://ve42.co/AtomicArchive https://ve42.co/BrokenArrowsReport
Declassified Goldsboro Report -- https://ve42.co/Goldsboro
Operation ChromeDome -- https://ve42.co/OperationChromeDome
CIA website -- https://ve42.co/CIA

Cataclysmic cargo: The hunt for four missing nuclear bombs after a B-52 crash -- https://ve42.co/WoPo
THE LAST FLIGHT OF HOBO 28 -- https://ve42.co/lastflight
The Voice of Larry Messinger is from this documentary -- https://ve42.co/Messinger
Even Without Detonation, 4 Hydrogen Bombs From ’66 Scar Spanish Village -- https://ve42.co/NYTPalomares
Decades Later, Sickness Among Airmen After a Hydrogen Bomb Accident -- https://ve42.co/NYTPalomares2
Picture of ReVelle -- https://ve42.co/JackReVelle1
Great NPR where the audio of ReVelle is from -- https://ve42.co/JackReVelle2
CIA Website -- https://ve42.co/CIA


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Special thanks to our Patreon supporters:
Anton Ragin, Balkrishna Heroor, 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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Directed by Petr Lebedev
Written by Petr Lebedev and Derek Muller
Edited by Peter Nelson
Animated by Fabio Albertelli, Jakub Misiek, Ivy Tello and Mike Radjabov
Filmed by Derek Muller
Produced by Petr Lebedev, Han Evans, and Derek Muller
Additional video/photos supplied by Getty Images and Pond5
Music from Epidemic Sound

People have witnessed supernovae for millennia, but what threat do they pose to life on Earth? 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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A massive thanks to Prof. Hans-Thomas Janka for helping us with the physics of supernovae and GRBs. A massive thanks to Prof. Brian Thomas for all of his help with the terrestrial effects of supernovae and GRBs. This video would not have been possible without them. Also thanks to Dr. Luke Barnes for his initial help with the literature search.

Hydrogen bomb vs Supernova fact was taken from this great article by xkcd/Randall Munroe – https://what-if.xkcd.com/73/ (based on the calculation by Andrew Karam, 2002)

Cosmic bubble footage from
https://www.cfa.harvard.edu/ne....ws/1000-light-year-w

Neutrino driven SN explosion simulations from https://iopscience.iop.org/art....icle/10.1088/2041-82

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References:

Melott, A. et al. (2019). Hypothesis: Muon radiation dose and marine megafaunal extinction at the End-Pliocene supernova. Astrobiology, 19(6), 825-830. – https://ve42.co/Melott1

Thomas, B. C. et al. (2016). Terrestrial effects of nearby supernovae in the early Pleistocene. The Astrophysical Journal Letters, 826(1), L3 – https://ve42.co/Thomas1

Melott, A. L., & Thomas, B. C. (2019). From cosmic explosions to terrestrial fires?. The Journal of Geology, 127(4), 475-481. – https://ve42.co/Melott2

Fields, B. et al. (2019). Near-Earth supernova explosions: Evidence, implications, and opportunities. arXiv preprint arXiv:1903.04589. – https://ve42.co/Fields1

Thomas, B. C., Atri, D., & Melott, A. L. (2021). Gamma-ray bursts: not so much deadlier than we thought. Monthly Notices of the Royal Astronomical Society, 500(2), 1970-1973. – https://ve42.co/Thomas2

Melott, A. et al. (2004). Did a gamma-ray burst initiate the late Ordovician mass extinction?. International Journal of Astrobiology, 3(1), 55-61. – https://ve42.co/Melott3

Firestone, R. B. (2014). Observation of 23 supernovae that exploded less than 300 pc from Earth during the past 300 kyr. The Astrophysical Journal, 789(1), 29. – https://ve42.co/firestone1

Janka, H. T. (2017). Neutrino emission from supernovae. arXiv preprint arXiv:1702.08713. – https://ve42.co/Janka1

Janka, H. T., & Hillebrandt, W. (1989). Neutrino emission from type II supernovae-an analysis of the spectra. Astronomy and astrophysics, 224, 49-56. – https://ve42.co/Janka2

Janka, H. T. (2017). Neutrino-driven explosions. arXiv preprint arXiv:1702.08825. – https://ve42.co/Janka3

Karam, P. A. (2002). Gamma and neutrino radiation dose from gamma ray bursts and nearby supernovae. Health physics, 82(4), 491-499. – https://ve42.co/Karam1

Melott, A. L., Thomas, et al.. (2017). A supernova at 50 pc: effects on the Earth's atmosphere and biota. The Astrophysical Journal, 840(2), 105. – https://ve42.co/Melott4

Ludwig, P., et al. (2016). Time-resolved 2-million-year-old supernova activity discovered in Earth’s microfossil record. Proceedings of the National Academy of Sciences, 113(33), 9232-9237. – https://ve42.co/Ludwig1

Gritschneder, et al. (2011). The supernova triggered formation and enrichment of our solar system. The Astrophysical Journal, 745(1), 22. – https://ve42.co/Gritschneder1

Motizuki, Y., Takahashi, et al. (2009). An Antarctic ice core recording both supernovae and solar cycles. arXiv preprint arXiv:0902.3446. – https://ve42.co/Motizuki

Zucker, C. et al. (2022). Star formation near the Sun is driven by expansion of the Local Bubble. Nature, 601(7893), 334-337. – https://ve42.co/Zucker1

Hirata, K. et al.(1987). Observation of a neutrino burst from the supernova SN1987A. – https://ve42.co/Hirata1

Hayes, L. A., & Gallagher, P. T. (2022). A Significant Sudden Ionospheric Disturbance Associated with Gamma-Ray Burst GRB 221009A. Research Notes of the AAS, 6(10), 222.

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

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Written by Petr Lebedev & Derek Muller
Edited by Fabio Albertelli
Animation by Fabio Albertelli, Jakub Misiek, Alex Drakoulis, Ivy Tello, Mike Radjabov, and Charlie Davies
Filmed by Derek Muller
Additional Research by Kovi Rose & Katie Barnshaw
Video/photos supplied by NASA, ESA, Pond5, and Getty Images
Music from Epidemic Sound & Jonny Hyman
Produced by Derek Muller, Petr Lebedev, and Emily Zhang

My entry to the techNyou Science Ambassadors competition, visit www.facebook.com/talkingtechnology and www.youtube.com/technyouvids to find out more about these guys.

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

Huge thanks to Prof. Geraint Lewis for hours of consulting on this video so I could get these ideas straight in my own brain. Check out his YouTube channel: https://ve42.co/gfl or his books: https://ve42.co/GFLbooks

Amazing VFX, compositing, and editing by Jonny Hyman
2D animations by Ivy Tello
Filmed by Steven Warren and Raquel Nuno
Special thanks to Petr Lebedev for reviews and script consultation
Music by Jonny Hyman and from Epidemic Sound https://epidemicsound.com

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

Slow motion rocket exhaust footage from Joe Barnard at BPS.Space
https://www.youtube.com/channe....l/UCILl8ozWuxnFYXIe2

The rainiest place on earth isn’t where you might expect. Get exclusive NordVPN deal here ➵ https://NordVPN.com/veritasium. It’s risk free with Nord’s 30 day money-back guarantee!

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

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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Huge thanks to Okouchi-San and Dr. Sakai and everyone at NIED and the Large Scale Rainfall Simulator for their time, expertise and access to this amazing facility.

A big thank you to Prof. Olga Mavrouli and Prof. Bill Schulz for their invaluable expertise on the mechanisms of landslides.

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References:
Ulbrich, C. W. (1983). Natural variations in the analytical form of the raindrop size distribution. Journal of climate and applied meteorology, 1764-1775. – https://ve42.co/Ulbrich83

Van Boxel, J. H. (1997, November). Numerical model for the fall speed of rain drops in a rain fall simulator. In Workshop on wind and water erosion (Vol. 5, pp. 77-85). – https://ve42.co/Boxel87

Canuti, P., Focardi, P., & Garzonio, C. (1985). Correlation between rainfall and landslides. Bulletin of Engineering Geology & the Environment, 32(1).

Tsaparas, I., Rahardjo, H., Toll, D. G., & Leong, E. C. (2002). Controlling parameters for rainfall-induced landslides. Computers and geotechnics, 29(1), 1-27. – https://ve42.co/Tsaparas2002

Nakamura, H., & Oosawa, M. (2021, March). Effects of the underground discharge channel/reservoir for small urban rivers in the Tokyo area. In IOP Conference Series: Earth and Environmental Science (Vol. 703, No. 1, p. 012029). IOP Publishing. – https://ve42.co/Nakamura21

Guthrie, R. H., & Evans, S. G. (2004). Magnitude and frequency of landslides triggered by a storm event, Loughborough Inlet, British Columbia. Natural Hazards and Earth System Sciences, 4(3), 475-483. – https://ve42.co/Guthrie2004

Images & Video:
Miyako, Iwate Tsunami via ANNnewsCH - https://ve42.co/Miyako2011
Mount Onake Volcano via BBC News - https://ve42.co/BBCOnake
Typhoon Jebi via Al Jazeera - https://ve42.co/TyphoonJebi
East Asia Typhoons via CBC News - https://ve42.co/TyphoonCBC
Atami Landslide via The Quint - https://ve42.co/Atami2021
Atami Landslide via news.com.au - https://ve42.co/2ndAtami2021
Sendai Earthquake via ANNnewsCH - https://ve42.co/SendaiQuake
Nagasaki Mudslide via The Telegrap - https://ve42.co/NagasakiMudslide
Wajima Landslide via Guardian News - https://ve42.co/WajimaLandslide
Drone Rainfall Test via AIZAWAchan - https://ve42.co/DroneRain
Car Rainfall Test via TIER IV - https://ve42.co/CarRainTest
Rainfall Simulator via NIED - https://ve42.co/RainfallSim1
External Footage of Simulator via NIED - https://ve42.co/RainfallSim2
Landslide Simulations via NIED - https://ve42.co/RainfallSim3
Typhoon Prapiroon via Force Thirteen - https://ve42.co/TyphoonPrapiroon
Yanohigashi Floods via CNA - https://ve42.co/YanohigashiFloods
Japan Floods via The Telegraph - https://ve42.co/TelegraphFlood
Japan Floods via euronew - https://ve42.co/EuroNewsFlood
Typhoon Hagibis via Guardian News - https://ve42.co/TyphoonHagibis
Typhoon Hagibis via SCMP - https://ve42.co/TyphoonHagibisSCMP
Satellite Imagery of Hagibis via Force Thirteen - https://ve42.co/HagibisSatellite
Tokyo Flood Control System via NikkeiAsia.com - https://ve42.co/FloodControl
Landslides Footage via Underworld - https://ve42.co/MonsterLandslides
Norway Landslide via ABC7 - https://ve42.co/NorwayLandslide
Planet Destruction via BBC - https://ve42.co/BBCDestruction
B.C. Climate Change Danger via CBC News - https://ve42.co/BCClimateChange
Canada’s Logging Roads via CBC News - https://ve42.co/CBCLogging

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

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Directed by Petr Lebedev
Written by Petr Lebedev
Edited by Peter Nelson
Additional Research by Gregor Čavlović
Animated by Fabio Albertelli
Illustrations by Jakub Misiek
Filmed by Petr Lebedev, Emily Zhang, Derek Muller
Produced by Petr Lebedev, Han Evans and Gregor Čavlović
Thumbnail by Peter Sheppard
Additional video/photos supplied by Getty Images
Music from Epidemic Sound

Adhesives based on gecko skin can hold huge weights – without sticking to anything. Head to https://brilliant.org/Veritasium to start your free trial. The first 200 of you will get 20% off Brilliant’s annual premium subscription.

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Thanks to Dr. Mark Cutkosky, Tony Chen, Amar Hajj-Ahmad, and the rest of the Biomimetics and Dexterous Manipulation Lab at Stanford University for showing us the power of gecko adhesives.

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References:
Russell, A. P., Stark, A. Y., & Higham, T. E. (2019). The integrative biology of gecko adhesion: historical review, current understanding, and grand challenges. Integrative and comparative biology, 59(1), 101-116. – https://ve42.co/Russell2019

Hajj-Ahmad, A., Suresh, S. A., and Cutkosky, M. R. (June 6, 2021). "Cutting to the Point: Directly Machined Metal Molds for Directional Gecko-Inspired Adhesives." ASME. J. Micro Nano-Manuf. – https://ve42.co/Hajj-Ahmad2021

Kerst, Capella F., "Gecko inspired adhesives : permanent practical manufacturing, new materials, and applications," PhD Thesis, Stanford University, December 2020. – https://ve42.co/Kerst2020

Suresh, S.A. "Engineering Gecko-Inspired Adhesives." Ph.D. thesis, Stanford University, 2020. [Online]. – https://ve42.co/Suresh2020

Suresh, S.A., Kerst, C.F., Cutkosky, M.R., Hawkes, E.W. "Spatially variant microstructured adhesive with one-way friction." Journal of the Royal Society Interface. 2019. – https://ve42.co/Suresh2019

Glick, P., Suresh, S.A., Ruffatto III, D., Cutkosky, M.R., Tolley, M.T., and Parness, A. "A soft robotic gripper with gecko-inspired adhesive." Robotics and Automation Letters. 2018. – https://ve42.co/Glick2018

Christensen, D.L., Hawkes, E.W., Suresh, S.A., Ladenheim, K. and Cutkosky, M.R., "µTugs: Enabling Microrobots to Deliver Macro Forces with Controllable Adhesives," IEEE/ICRA 2015 (preprint). – https://ve42.co/Christensen2015

Hawkes, E. W., "Applying Dry Adhesives to the Real World," Ph.D. thesis, Stanford University, 2015. – https://ve42.co/Hawkes2015

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Special thanks to our Patreon supporters:
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Written by Derek Muller & Petr Lebedev
Edited by Trenton Oliver
Animation by Ivy Tello
Filmed by Derek Muller & Albert Leung
Additional video/photos supplied by Pond5 & Getty Images
Music from Epidemic Sound
Exec. Produced by Derek Muller, Petr Lebedev, and Emily Zhang

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.
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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

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

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