Scientists are being inspired by nature to design the next generation of security devices. Arrays of nanoscale holes create beautiful reflected colours that are almost impossible to forge. This video was supported by TechNyou - check out their series on logical fallacies: http://bit.ly/WBsD31

Soon these nanoscale security devices could replace holograms. They are many times more reflective than holograms, and although the structures are smaller scale, they are lower aspect ratio and therefore easy to manufacture in bulk.

The electron wiggle simulation is from PhET, the best physics simulations ever: http://phet.colorado.edu

Special thanks to Thomas from Copenhagen who showed me around the city including the science museum where he assisted with the soap bubble demonstration.

Clint Landrock is the Chief Technology Officer for Nanotech Securities: http://www.nanosecurity.ca

Music is "Firefly in a Fairytale" by Gareth Coker

What it's like to see the Earth from orbit.
Special thanks to Col. Chris Hadfield for chatting with me. http://chrishadfield.ca/

Space imagery courtesy of NASA and the ESA
http://eol.jsc.nasa.gov/
http://www.esa.int/spaceinvideos/Videos

Music by Kevin MacLeod "New Frontier" http://incompetech.com
And "Eureka" by Huma-Huma

Bayes' theorem explained with examples and implications for life.
Check out Audible: http://ve42.co/audible
Support Veritasium on Patreon: http://ve42.co/patreon

I didn't say it explicitly in the video, but in my view the Bayesian trap is interpreting events that happen repeatedly as events that happen inevitably. They may be inevitable OR they may simply be the outcome of a series of steps, which likely depend on our behaviour. Yet our expectation of a certain outcome often leads us to behave just as we always have which only ensures that outcome. To escape the Bayesian trap, we must be willing to experiment.

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

Useful references:
The Signal and the Noise, Nate Silver
The Theory That Would Not Die: How Bayes’ Rule Cracked the Enigma Code, Hunted Down Russian Submarines, and Emerged Triumphant from Two Centuries of Controversy, by Sharon Bertsch McGrayne

Bayes' theorem or rule (there are many different versions of the same concept) has fascinated me for a long time due to its uses both in mathematics and statistics, and to solve real world problems. Bayesian inference has been used to crack the Enigma Code and to filter spam email. Bayes has also been used to locate the wreckage from plane crashes deep beneath the sea.

Music from http://epidemicsound.com "Flourishing Views 3"

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

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

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

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

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

A boomerang can execute its unique roundtrip flight by making use of three fundamental physics principles: lift, relative velocity, and gyroscopic precession.

numberphile http://bit.ly/numberphile
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appchat http://bit.ly/NxAMlX
erikaanear http://bit.ly/MdyUzQ
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These are the molecular machines inside your body that make cell division possible. Animation by Drew Berry at the Walter and Eliza Hall Institute of Medical Research. http://wehi.tv

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

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

Every day in an adult human roughly 50-70 billion of your cells die. They may be damaged, stressed, or just plain old - this is normal, in fact it’s called programmed cell death.

To make up for that loss, right now, inside your body, billions of cells are dividing, creating new cells.

And cell division, also called mitosis, requires an army of tiny molecular machines.DNA is a good place to start - the double helix molecule that we always talk about.

This is a scientifically accurate depiction of DNA. If you unwind the two strands you can see that each has a sugar phosphate backbone connected to the sequence of nucleic acid base pairs, known by the letters A,T,G, and C.

Now the strands run in opposite directions, which is important when you go to copy DNA. Copying DNA is one of the first steps in cell division. Here the two strands of DNA are being unwound and separated by the tiny blue molecular machine called helicase.
It literally spins as fast as a jet engine! The strand of DNA on the right has its complimentary strand assembled continuously but the other strand is more complicated because it runs in the opposite direction.
So it must be looped out with its compliment strand assembled in reverse, section by section. At the end of this process you have two identical DNA molecules, each one a few centimeters long but just a couple nanometers wide.

To prevent the DNA from becoming a tangled mess, it is wrapped around proteins called a histones, forming a nucleosome.
These nucleosomes are bundled together into a fiber known as chromatin, which is further looped and coiled to form a chromosome, one of the largest molecular structures in your body.
You can actually see chromosomes under a microscope in dividing cells - only then do they take on their characteristic shape.

The process of dividing the cell takes around an hour in mammals. This footage is from a time lapse. You can see how the chromosomes line up on the equator of the cell. When everything is right they are pulled apart into the two new daughter cells, each one containing an identical copy of DNA.
As simple as it looks, this process is incredibly complicated and requires even more fascinating molecular machines to accomplish it. Let’s look at a single chromosome. One chromosome consists of two sausage-shaped chromatids - containing the identical copies of DNA made earlier. Each chromatid is attached to microtubule fibers, which guide and help align them in the correct position. The microtubules are connected to the chromatid at the kinetochore, here colored red.
The kinetochore consists of hundreds of proteins working together to achieve multiple objectives - it’s one of the most sophisticated molecular mechanisms inside your body. The kinetochore is central to the successful separation of the chromatids. It creates a dynamic connection between the chromosome and the microtubules. For a reason no one’s yet been able to figure out, the microtubules are constantly being built at one end and deconstructed at the other.
While the chromosome is still getting ready, the kinetochore sends out a chemical stop signal to the rest of the cell, shown here by the red molecules, basically saying this chromosome is not yet ready to divide
The kinetochore also mechanically senses tension. When the tension is just right and the position and attachment are correct all the proteins get ready, shown here by turning green.
At this point the stop signal broadcasting system is not switched off. Instead it is literally carried away from the kinetochore down the microtubules by a dynein motor. This is really what it looks like. It has long ‘legs’ so it can avoid obstacles and step over the kinesins, molecular motors walking the other direction.

Studio filming by Raquel Nuno

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

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

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

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

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

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

MORE INFO:

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

The solution to 4 rotation-related riddles, including the mystery cylinder, bike pedal pulling puzzle, track problem, and train part going backwards. Thank you to everyone who responded, liked, shared, or made a video response.
Please fill out this short survey for research: http://ve42.co/Rresearch

Special thanks to:
Mathematician George Hart: http://georgehart.com/
For allowing me to use excerpts from his pedal pulling puzzle solution: http://ve42.co/ppp

Petr Lebedev for combing through thousands of comments and providing the stats I gave in this video.

Video responses I used in this video (or watched):
everWonder? https://www.youtube.com/watch?v=5Ub2Cuclh1M
A Random Nerdy Channel https://www.youtube.com/watch?v=I9RB9TrZGps
The Physics DoJo https://www.youtube.com/watch?v=Pns0LCGLu9k
Oblivious Jim https://www.youtube.com/watch?v=12WZIMEPi1A
Armchair Explorers https://www.youtube.com/watch?v=S1yX_LTqtms
MrEngineeringGuy https://www.youtube.com/watch?v=DRF82Rx9_YI
Professor Cubers https://www.youtube.com/watch?v=qOd5orH-jfM
Scoop Science https://www.youtube.com/watch?v=uzLO6GqmfhI

A few notes on the puzzle:
1. A half-full container of honey does pretty well in reproducing the behaviour of the mystery cylinder. I wonder if the motion is a little smoother or more periodic with the ping-pong balls because they move as organized objects - also the delays between motion seemed to be longer with them than without ping pong balls.

2. For the average speed track problem, every time I said velocity I meant speed. Sorry to the pedants out there who are perhaps looking for some trick answer due to displacement being zero when you run around a track.

3. Although a lot of people identified it was something about a train's wheels that move backwards, fewer identified that specifically it was the part of the flange below the rail. Some simply said the bottom half of the wheel.

4. The bicycle question is perhaps the most complex of these riddles. If you tried it with a bike you likely found that it went backwards. But what happens if you sit on the bike and only push backwards on the bottom pedal. The answer might surprise you so give it a shot!

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

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?

All the large-scale structure in the universe may owe its existence to nothing.
Sponsored by the Dyson 360 Eye Robot #ad: http://bit.ly/2cGqBRV
Support Veritasium on Patreon: http://bit.ly/VePatreon

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

Let's see how clearly I can explain this. We think of empty space as, well... empty, the epitome of nothingness. But as our understanding of physics has evolved we have realized that it's not truly empty. Space is filled with fields. There is a field for every subatomic particle. One for electrons, up quarks, down quarks, neutrinos and so on. In empty space these fields are basically zero, flat, nil. But it's impossible to make them perfectly zero so there are always some quantum fluctuations in the fields, even in a perfect vacuum. These are sometimes called virtual particles but they should really just be thought of as little disturbances in the field. Vacuum fluctuation play a role mediating the interactions of subatomic particles but they don't really have an impact on the large-scale structure of the universe, EXCEPT during inflation, right after the big bang when the universe increased in size 10^26 times. Due to this rapid expansion, those tiny fluctuations were blown up to the scale of the observable universe. And we know this by looking at the cosmic microwave background radiation where we can see slightly hotter and cooler parts of the early universe that correspond to density fluctuations. And it is these density fluctuations that allowed matter to clump together into large structures like the gigantic gas clouds that would go on to contain stars and planets. In case the video isn't clear, this is what I've been trying to say.

Animations by Gustavo Rosa

This video was sponsored in part by Dyson #ad

Mounting evidence suggests a lot of published research is false.
Check out Audible: http://bit.ly/AudibleVe
Support Veritasium on Patreon: http://bit.ly/VePatreon

Patreon supporters:
Bryan Baker, Donal Botkin, Tony Fadell, Jason Buster, Saeed Alghamdi

More information on this topic: http://wke.lt/w/s/z0wmO

The Preregistration Challenge: https://cos.io/prereg/

Resources used in the making of this video:

Why Most Published Research Findings Are False:
http://journals.plos.org/plosm....edicine/article?id=1

Trouble at the Lab:
http://www.economist.com/news/....briefing/21588057-sc

Science isn't broken:
http://fivethirtyeight.com/fea....tures/science-isnt-b

Visual effects by Gustavo Rosa

Watch the bullet block experiment first: http://bit.ly/bulletblock
Click for a free audiobook from Audible: http://bit.ly/ZJ5Q6z
An interactive vignette of the bullet block http://ivv.rit.edu/bby/

Can you figure out the spinning disk? http://bit.ly/spinningdisk

Thank you all for the awesome video responses and comments!!

Simulation: http://bit.ly/19SCVnl
Web comic: http://bit.ly/17o8HrR
Wired Blog: http://bit.ly/17o9Dwu
Science Blogs: http://bit.ly/17o9au3
Scientific American: http://bit.ly/19SDoWC
Le's Blog: http://bit.ly/18q1m8a

Video responses from which I borrowed:
http://www.youtube.com/watch?v=hup-l4_Qt_U
http://www.youtube.com/watch?v=uwZ1Mhy0BS0
http://www.youtube.com/watch?v=SgylTbknFdM

Thanks to everyone at RIT and Dickinson College who helped with the making of this video:
Rochester Institute of Technology
Robert Teese, Katelyn Wilkerson, Andrew Gillie, Andrew Stidwill

Dickinson College
This experiment was the brainchild of David Jackson based on a demo at Princeton.
Priscilla Laws, Catrina Hamilton-Drager, Maxine Willis

High-speed camera support:
Charles Zwemer and Bria Antoine

Music: Temper Trap "Love Lost (Instrumental)" and Lights & Motion "Epilogue" licensed from CueSongs.com

Watch this first! https://www.youtube.com/watch?v=QD3hbVG1yxM
Follow on Twitter: https://twitter.com/veritasium
Follow on Facebook: https://www.facebook.com/veritasium

Special thanks to the Department of Earth, Planetary and Space Sciences, especially Gary for helping source the equipment and Raquel for filming.

If you repeat something enough times, it comes to feel good and true.
Support Veritasium on Patreon: http://bit.ly/VePatreon
Science with Hot Wheels! My vids for kids: http://bit.ly/VeHotWheels
More info on cognitive ease: http://bit.ly/29OMGas

This episode was inspired by the book Thinking Fast and Slow by Daniel Kahneman.

This video was edited by Daniel Joseph Files, with music from Kevin MacLeod at http://incompetech.com "Marty Gots a Plan" "Sing Along With Jim" and "Full On".

Veritasium is supported on Patreon by:
Jason Buster, Saeed Alghamdi, Tony Fadell, Donal Botkin, Bryan Baker, & Imthetroublesolver 8)

SYNCHRONIZE WITH DESTIN’S VIDEO: http://bit.ly/NorthernSwirl
Both videos on one page (for desktop): http://bit.ly/ToiletSwirl
Subscribe to Smarter Every Day: http://bit.ly/SubscribeSED
Click to tweet: http://bit.ly/ToiletSwirlTWT

Some notes:
We each repeated the experiment 3 times, and got the same results every time. For those of you who might be skeptical, great! A right circular prismatic kiddie pool is only $10 and you can do the experiment for yourself at your latitude. There's really no reason you shouldn't do it for yourself.

Veritasium on Instagram: http://instagram.com/veritasium
Patreon Support Link: http://www.patreon.com/veritasium
Twitter: http://twitter.com/veritasium
http://www.facebook.com/veritasium

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

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

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

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

MORE INFO:

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

How much information is there in Spanish vs English, you vs the world? Check out Audible: http://bit.ly/AudibleVe
Huge thanks to all the amazing people who made this possible:
Christina Ochoa - Spanish https://twitter.com/christina_ochoa
Vanessa Hill - Filming https://www.youtube.com/braincraftvideo
Henry Reich - Filming, cameo http://youtube.com/minutephysics
Cara Santa Maria - Set design http://carasantamaria.com
Michael Stevens - cameo http://youtube.com/vsauce
Crystal Dilworth - consultation https://twitter.com/PolycrystalhD

Thanks also to MinutePhysics for wardrobe and lending the use of the amazing "Things to do when it's really cold outside" video: https://www.youtube.com/watch?v=j3Gs6tyiNX4

More on this theme to come in the main collaboration with Vsauce.

http://www.abc.net.au/catalyst/team/default.htm
I have been working with Catalyst on ABC1 to bring some Veritasium to Australian TV. In this segment I ask why astronauts in the space station are weightless. The most common answer is because there is no gravity in space. But of course there is gravity in space, especially where the space station is located (only about 400km from Earth's surface). So astronauts still experience a gravitational pull - it's just that they and the space station are in free fall so they are accelerating together towards the Earth. The space station doesn't crash into the Earth because of its orbital velocity - it's going 28,000 km/h so as it falls, the Earth curves away from it.

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