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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

When evolution favours a stable ratio of traits rather than one dominant trait.
Check out Audible: http://bit.ly/AudibleVe
Animation by The Lyosacks: https://www.youtube.com/TheLyosacks

Hosting Neil Degrasse Tyson, info and tickets: http://bit.ly/NDTandVe
Aug. 22 in Sydney
Aug. 23 in Canberra

Special thanks to Richard Dawkins

Filmed at Academia Film Olomouc with help from Martyn Marek

Music by Kevin MacLeod www.incompetech.com 'Marty Gots a Plan' 'Sing Along with Jim'

Scientists have recently discovered nanodiamonds in the flames of ordinary candles. They are produced at a rate of about 1.5 million per second. Unfortunately they are also burned up at this rate and released into the atmosphere as carbon dioxide. Still this finding may prove useful in the ongoing search for economical ways to produce diamonds.

Which weight hits the ground first - the free weight or the weight attached to the chain?

The strange thing about high jump is that the technique changed dramatically after 1968, when Dick Fosbury used his trademark flop to win the gold medal at the Olympics in Mexico City.
Previously the scissors and straddle had been the most common jumping technique, but after the introduction of safer landing matts, the new unorthodox Fosbury Flop became the jump of choice. There are good physical reasons for this - the style allows the jumper to pass over the bar while his or her centre of mass actually passes below the bar.

Huge thanks to Elly (Appchat http://bit.ly/NxAMlX ) for filming, editing, and music!

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

Aerogels are the world's lightest (least dense) solids. They are also excellent thermal insulators and have been used in numerous Mars missions and the Stardust comet particle-return mission. The focus of this video is silica aerogels, though graphene aerogels are now technically the lightest.

At one point Dr. Steven Jones literally held the Guinness World Record for making the lightest aerogel and therefore lightest solid. If you're interested in learning more about aerogels, let me know in the comments as there is a potential trilogy in the works...

Huge thanks to Dr. Stephen Steiner and the crew at Aerogel Technologies. To find out more or buy your own aerogel sample, check out: http://www.aerogeltechnologies.com/

Thanks to Dr. Steven Jones and Dr. Mihail Petkov at NASA's Jet Propulsion Laboratory

And thanks to FLIR for loaning us the awesome high definition thermal camera. The footage is amazing! https://www.flir.com

Special thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Ron Neal, Stan Presolski, Terrance Shepherd, Penward Rhyme and everyone who provided feedback on an early draft of this video.

Filming by Raquel Nuno
Animations by Maria Raykova
Drawings by Mariel Solsberg

Music From http://epidemicsound.com "Seaweed" "Swagger Stagger"

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

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!

The Earth spins on its axis, completing a full revolution every day. By why does it do this? One of the most common misconceptions in physics is the belief that constant motion requires a constant force. So many people believe there must be some force in the Earth (e.g. gravity, centrifugal force) that keeps it spinning. In truth, no force is required because a fundamental property of mass is that it maintains its state of motion in the absence of external forces. This property is called inertia.

A launch mishap led to the best experimental confirmation of gravitational redshift. Get a free audiobook with a 30-day trial of Audible: http://audible.com/VERITASIUM or text VERITASIUM to 500500

Huge thanks to
Dr. Pacome Delva: https://ve42.co/pacome
Dr. Sven Herrmann: https://ve42.co/sven
Gravitational Redshift Test Using Eccentric Galileo Satellites: https://ve42.co/GRtest

Disclaimer: It is arguable what is THE best test of general relativity because there are different ways to test the theory. This is the best confirmation of gravitational redshift, which is one of the three original tests proposed by Einstein.

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

Animations and editing by Alan Chamberlain

Music from http://epidemicsound.com "Subtle Substitutes 2" "A sound Foundation 1" "Cell Research 1" "Particle Attraction 1"

Scientists have JUST published this new observation. On January 4th, 2017 they detected the merger of two black holes 3 billion light-years away. This marks the furthest detection they've been able to make and increases confidence that these events will be seen with increasing frequency as the LIGO interferometers become more sensitive to low amplitude gravitational waves (as sources of noise are eliminated).

Special thanks to:
Prof. Rana Adhikari
Prof. David Reitze

Resources by:
Binary Neutron Star merger: Relastro @ ITP - Goethe University, Frankfurt https://www.youtube.com/watch?v=nOTXC4FG9gU
Numerical simulation of black hole merger:
S. Ossokine/A. Buonanno/T. Dietrich (MPI for Gravitational Physics)/R. Haas (NCSA)/SXS project
Artist's impression of merger and chart: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)
Simulation of black hole merger: SXS Collaboration

Special thanks to Patreon Supporters:
Tony Fadell, Donal Botkin, Jeff Straathof, Zach Mueller, Ron Neal, Nathan Hansen

Support Veritasium on Patreon: http://ve42.co/patreon

Sound Recording by Raquel Nuno

NEW CHANNEL! http://youtube.com/sciencium

For a long time we thought the Moon was completely dry, but it turns out there are actually three sources of lunar water.
Thanks to Google Making and Science for supporting the new channel! http://youtube.com/makingscience

Thanks to Patreon supporters:
Nathan Hansen, Donal Botkin, Tony Fadell, Zach Mueller, Ron Neal

Support Veritasium on Patreon: http://bit.ly/VePatreon

References:
Great history of water on the moon: https://arxiv.org/pdf/1205.5597.pdf

Filmed by Raquel Nuno

Music from http://epidemicsound.com "Serene Story 2"

The crazy story of the arbitrary temperature scale used in a tiny minority of countries.
Check out Audible: http://bit.ly/AudibleVe
Snatoms are available again! http://www.snatoms.com
Support Veritasium on Patreon: http://bit.ly/VePatreon

Celsius didn't invent Celsius: http://bit.ly/VeCelsius

Video animated by Marcello Ascani: http://bit.ly/VeMarcello

Thanks to Patreon supporters:
Nathan Hansen, Bryan Baker, Donal Botkin, Tony Fadell, Saeed Alghamdi

Music by Kevin MacLeod: http://incompetech.com "Modern Piano Zeta - Improbable" "Ice Demon" "Divertimento K131" "Sneaky Adventure" "Sheep May Safely Graze" "Professor and the Plant"

References:
A History of the Thermometer and its uses in Meteorology by W. E. Knowles Middleton

Absolute Zero and the Conquest of Cold by Tom Shachtman

The Science of Measurement, A Historical Survey by Herbert Arthur Klein

Lehrbuch der Chemie by Jöns Jakob Berzelius

Script:
As an Australian-Canadian the Fahrenheit temperature scale always seemsed a bit arbitrary. I mean why does water freeze at 32 degrees? And what exactly does zero represent?

According to many sources the Fahrenheit scale was defined by setting zero degrees equal to the temperature of an ice, salt, and water mixture and 100 degrees being roughly equal to human body temperature. But that isn’t true.

The real story is much more interesting, and scientific...

August 14th 1701 was almost certainly the worst day in the life of fifteen year-old Daniel Gabriel Fahrenheit. On that day both of his parents died suddenly from mushroom poisoning. He was sent from Poland, where he lived, to Amsterdam to become an apprentice bookkeeper.

But Fahrenheit couldn’t stand his apprenticeship and ran away so many times his employers put out a warrant for his arrest. Traveling from city to city around Europe, he became fascinated with scientific instruments and in particular thermometers.

In 1708, possibly seeking help with the warrant, Fahrenheit met with the mayor of Copenhagen, who happened to be the famous astronomer Ole Romer.

Romer is known for observing the eclipses of Jupiter’s moons and realizing that variations in the timing of those eclipses was caused by the time it took light to reach Earth. In other words, he found a way to accurately measure the finite speed of light.

But more pertinent to this story, in 1702 Romer was housebound after breaking his leg. To pass the time he devised a new temperature scale with the freezing point of water at 7.5 degrees and body temperature at 22.5 degrees.

This might seem odd until you consider that Romer wanted the boiling point of water to be 60 degrees (as an astronomer, he had experience dividing things by 60). If you take this scale, divide it in half, in half again, and in half once more, you find the freezing point of water 1/8th up the scale, and human body temperature 3/8th up the scale.

So at their meeting in 1708, Fahrenheit learned of Romer’s temperature scale and adopted it as his own, adjusting it slightly because he found it “inconvenient and inelegant on account of the fractional numbers”. So he scaled them up to 8 and 24.

That is the original Fahrenheit scale. He produced thermometers for some time using this scale.

But then, at some later time Fahrenheit multiplied all numbers on his scale by four, setting freezing point to the now familiar 32 and body temperature to 96. It’s unclear exactly why he did this. He may just have wanted finer precision in his measurements but I think there was a better reason.

You see, Fahrenheit was an excellent instrument maker. His thermometers agreed with each other precisely, at a time when that was unheard of. He pioneered the use of mercury as a measuring liquid, which has the benefit of a much higher boiling point than the alcohol used in most other thermometers at the time. For these accomplishments, he was inducted into the British Royal Society.

And we know he read the works of Newton, Boyle, and Hooke, in which he would have come across the idea that a one degree increase in temperature should correspond to a specific fractional increase in the volume of the measuring liquid.

And today a one degree Fahrenheit increase in temperature increases the volume of mercury by exactly one part in 10,000. Is this just a coincidence? We’ll probably never know for sure because as an instrument maker Fahrenheit was secretive about his methods. But I think the data strongly suggests this was the case.

So what exactly did zero represent on the scales of Fahrenheit and Romer? By many accounts it’s the temperature of a salt, ice and water mixture. But there are different descriptions of these mixtures and none of them actually produces the temperature they’re supposed to. More likely I think they picked the coldest temperature in winter, set that as zero and later used ice and brine to calibrate new thermometers. Now his scale is only used regularly in the Cayman Islands, Bahamas, Belize, oh and the United States of America.

UV at ground level is non-ionizing but it damages DNA and causes photoaging - how?
Also, it turns out glass doesn't block all UV (specifically UVA passes through). This is something I learned filming with the UV camera inside.

Special thanks to Dr. Hayley Golbach, @hayleysgold on twitter
https://twitter.com/hayleysgold

Ultraviolet light causes damage to DNA, leads to cancer and photoaging: age spots and wrinkles. I was curious about this because UV is technically non-ionizing. A photon of UV doesn't have enough energy to strip an electron off atoms or molecules. However it does have enough energy to trigger photo-chemical reactions. For example, it causes pyrimidine dimers - the unauthorized covalent bonding of adjacent thymine or cytosine bases in our DNA. If these spots are not properly repaired, they may lead to mutations and cancer. Photoaging is typically the result of degradation of collagen and elastin fibers - scaffolding that supports the skin. This leads to wrinkles and saggy-looking skin.

Huge thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Jeff Straathof, Zach Mueller, Ron Neal, Nathan Hansen, Yildiz Kabaran, Terrance Snow, Stan Presolski, James M Nicholson, KIMoFy

Support Veritasium on Patreon: http://ve42.co/patreon

Music from Epidemic Sound http://epidemicsound.com "Serene Story 2"

Check out 2Veritasium! http://dft.ba/-ve2
MinutePhysics has a great video on Milkman, vomiting levitator: http://dft.ba/-vomphysics
Jetpacking was awesome fun! Despite the fat lip I had a great time. I think knowing a bit about physics actually helps fly the jetpack. It works on the same principle as a rocket (Newton's 3rd law) but unlike the shuttle, you don't carry your own propellant with you. Instead, water is pumped out of the lake by the jetski at up to 60 litres a second. It is then fired out of the nozzles at around 15 m/s creating 1800 N of force, the equivalent of about 150 fire extinguishers. On me this can produce acceleration of about 1.5g's.

Music by Kevin McLeod (http://incompetech.com) Silly Fun, Also Sprach Zarathustra
Supported by Science Alert: http://on.fb.me/14ehuxA
Slow motion filming by Questacon: http://bit.ly/ZoWFGR

Acrylic Ball: http://bit.ly/BBBacrylic
Ping-Pong Ball: http://bit.ly/BBBpingpong
Balanced: http://bit.ly/BBBbalanced

This problem has made the rounds on the internet but I felt it deserved a treatment like this.

Special thanks to Gary and the Department of Earth, Planetary and Space Sciences at UCLA, to the students for participating, to Ivy for helping me coordinate everything and to Raquel for filming.

Music by Kevin MacLeod, http://incompetech.com "Monkeys, Spinning Monkeys"

An experiment on how turbulent convection in Earth's core makes a magnetic field
Get a free audiobook with a free 30 day trial at http://www.audible.com/Veritasium or text Veritasium to 500-500

Huge thanks to Prof. Dan Lathrop and team: http://ve42.co/Lathrop

Companion video to explain Earth's magnetic fields in more detail:
https://youtu.be/lWHxmJf6U3M

Australians! I'm on my way. I'll be doing live shows in Perth, Sydney and Melbourne. Details and tickets here: http://ve42.co/tour

Find out more about the film Vitamania: http://ve42.co/VITA

Special thanks to Brady Haran and Periodic Videos for sodium vs water footage. Original clip is here:
https://www.youtube.com/watch?v=mzEOL-N2cbw

Special thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Jeff Straathof, Zach Mueller, Ron Neal, Nathan Hansen, Yildiz Kabaran, Terrance Snow, Stan Presolski

I learned a lot in making this video and the one on my second channel with Prof. Jon Arnou. I changed a lot of my preconceptions, specifically I thought:

1. That the Earth's magnetic field was a passive thing - it shouldn't need a continuous input of energy to maintain itself (that seemed reasonable to me because the magnetic field has been around for a long time and it seems mostly stable). But as it turns out, the Earth is a giant electromagnet, and so of course those currents dissipate their energy as they encounter resistance in the liquid metal through which they flow. So the energy to continuously create these currents comes from the kinetic energy of the liquid metal flows in the Earth's outer core.

2. If it's convection, I'm thinking hot things rising, cooler things falling. But apparently the main effect driving convection is the compositional differences at the boundary with the Earth's inner core. This is because of the differential freezing at the boundary. Things like iron freeze into the inner core, while elements like sulfur do not. Hence the pockets of lighter material which then rise outwards.

3. I didn't get why the fluid motion was necessary for the generation of the magnetic field. I mean if it's a conducting liquid, it can conduct currents whether it moves or not. But the key is that the liquid metal can 'trap' magnetic fields. I imagine this like how iron channels magnetic fields. Then once these fields are channeled, they can be pulled and stretched, making more magnetic field.

4. Fluids operate very differently in rotating frames of reference. This is something I didn't intuitively grasp. But, as fluids move from the inner core outwards, those particles are moving much more slowly in the direction of rotation than the matter that has been there for a long time, which means the convection currents get deflected and form helices.

Music by Kevin MacLeod http://incompetech.com Brandenburg Concerto No4

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

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

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

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

Additional graphics by Ignat Berbeci

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

This is what a nuclear disaster area looks like.
Check out Audible: http://bit.ly/AudibleVe
Broadcast locations and times:

North America: PBS, July 28 & 29 @ 10pm ET / 9pm Central
Europe: ZDF/arte, July 31 @ 10pm
Australia: SBS, August 6, 13, 20 @ 8:30pm EST

Not broadcast in your country? Contact your local broadcaster and/or email www.genepoolproductions.com

Music by Kevin Macleod http://incompetech.com 'Come Play With Me' & 'Lost Frontier'

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

Huge thanks to:

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

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

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

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

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

Additional resources and references:

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

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

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

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

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

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

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

http://www.classictvinfo.com

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