In Queenstown, New Zealand, I jumped off the Kawarau Bridge - the site of the first bungy jump. It was a thrilling experience, preceded by a terrifying, gut-wrenching half hour wait. All in all an awesome adventure, even if the woman fitting my harness didn't know the first thing about the acceleration of free-falling bodies.

Tiny robots activated by magnetic fields may be used in future biomedical procedures. Start listening to Audible with a 30-day trial and your first audiobook, plus two Audible Originals free when you go to http://audible.com/veritasium or text veritasium to 500500

Huge thanks to:
Dr. Eric Diller, Assistant Professor of Mechanical Engineering at the University of Toronto
http://microrobotics.mie.utoronto.ca

Research Referenced in this video:

T. Xu, J. Zhang, M. Salehizadeh, O. Onaizah and E. Diller, Millimeter-scale flexible robots with programmable three-dimensional magnetization and motions. Science Robotics. 4, eaav4494 (2019).
http://robotics.sciencemag.org..../lookup/doi/10.1126/

H. Xie, M. Sun, X. Fan, Z. Lin, W. Chen, L. Wang, L. Dong, and Q. He, Reconfigurable magnetic microrobot swarm: Multimode transformation, locomotion, and manipulation. Science Robotics. 4, eaav8006 (2019).
http://robotics.sciencemag.org..../lookup/doi/10.1126/

G. Hwang, A. J. Paula, E. E. Hunter, Y. Liu, A. Babeer, B. Karabucak, K Stebe, V. Kumar, E. Steager, and H. Koo, Catalytic antimicrobial robots for biofilm eradication. Science Robotics. 4, eeaw2388 (2019).
http://robotics.sciencemag.org..../lookup/doi/10.1126/

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

Music by Kevin MacLeod http://incompetech.com "Marty Gots a Plan" "March of the Spoons"

It takes the moon about 27 days to orbit the Earth. What makes it go round? It is the gravitational attraction of the Earth on the moon. Due to the moon's velocity, the Earth keeps pulling the moon towards it without the moon actually getting closer to the Earth. This is similar to how satellites orbit the Earth.

Mosquitoes are attracted to me and it's likely due to my genes.
This video is sponsored by 23andMe https://23andme.com/veritasium
Huge thanks to Prof. Immo Hansen and team: http://ve42.co/hansen

References:
Genome Wide Association Study for self-reported mosquito attractiveness:
http://ve42.co/MossieGWAS

The twin study showing correlated attractiveness is stronger for identical twins:
http://ve42.co/MossieTwins

Some things we know make mosquitoes more attracted to you:
Exercising, higher metabolism, higher body temperature, more body odor, being pregnant, type O blood, infrequent bathing, lactic acid, ammonia, acetone.

There are a number of folk remedies people believe protect them from mosquito bites like drinking alcohol, eating garlic, or taking vitamin B. These do not appear to provide any benefit in lab studies and in fact drinking alcohol is associated with increased mosquito activity because it causes blood vessels near the surface of the skin to dilate.

And apparently some of your attractiveness to mosquitos is simply genetic. This may be mediated through your immune system, which is what a lot of the genes identified were associated with.

Molecular models are microSnatoms: http://snatoms.com

Filming in New Mexico by Raquel Nuno
Animations by Jacqui Robertson

The opinions and conclusions drawn in this video are those of Veritasium and not 23andMe.

Negative Pressure Exists! http://bit.ly/TFilQ8
Vsauce's Space Straw: http://bit.ly/XubIm3
Smarter Every Day's Prince Rupert's Drop: http://bit.ly/10VQBGW
ViHart's Optimal Potatoes: http://bit.ly/14egJoe

Thanks to Questacon for filming! Check out their slow-mo playlist: http://bit.ly/ZoWFGR
Science Alert brings science to your news feed: http://on.fb.me/14ehuxA

Music by Kevin Mcleod (http://incompetech.com): Pale Rider & The Cannery

Veritasium is a channel of science and engineering videos featuring experiments, expert interviews, cool demos, and discussions with the public about everything science.
Clips featured in this video:
Trees are Freaking Awesome - http://bit.ly/TFilQ8
Gyroscopic Precession - http://bit.ly/U4e8HQ
Can We Go The Speed of Light? (Principle of Relativity) - http://bit.ly/X1BlXZ
Where Does The Sun Get Its Energy? - http://bit.ly/125jbeM
Where Do Trees Get Their Mass? - http://bit.ly/11AA817
What Is A Candle Flame Made Of? - http://bit.ly/Q3enCb
Levitating Barbecue (Electromagnetic Induction) - http://bit.ly/SWgOWh
Imploding Drum - http://bit.ly/125jG8B
Microwave Grape Plasma - http://bit.ly/QkCwUt
Spinning Tube Trick - http://bit.ly/Va43Z6
Spinning Disk Trick - http://bit.ly/14MSKsT
Why Do You Make People Look Stupid? - http://bit.ly/12Fmlpl
Awesome HD Slinky Slow-Mo - http://bit.ly/TRa4sE
Subscribe to Veritasium - http://bit.ly/YSWpWm

Subscribe to Veritasium - it's FREE! http://bit.ly/YSWpWm
Check out other unanswered science questions: http://youtu.be/UFydagCS9fg

The universe is huge. That means two things: 1. there is probably life elsewhere, 2. It is likely too far away to have reached us.

Fast, Furious & Funny - http://www.youtube.com/fastfuriousand... (http://www.youtube.com/watch?v=YWxub2...)

The Brain Scoop - http://www.youtube.com/thebrainscoop (http://youtu.be/mNuu0y6ZmAs)

ASAPScience - http://www.youtube.com/AsapSCIENCE (http://www.youtube.com/watch?v=wgxJhp...)

The Royal Institute of Great Britain - http://www.youtube.com/TheRoyalInstit... (http://www.youtube.com/watch?v=gm02Oi...)

PBS Idea Channel - http://www.youtube.com/pbsideachannel (http://www.youtube.com/watch?v=TbNymw...)

The Spangler Effect - http://www.youtube.com/TheSpanglerEffect (http://www.youtube.com/watch?v=4fQ4uB...)

Minute Physics - http://www.youtube.com/minutephysics (http://www.youtube.com/watch?v=2yHDeK...)

Head Squeeze - http://www.youtube.com/HeadsqueezeTV (http://www.youtube.com/watch?v=UPBJX1...)

Vsauce - http://www.youtube.com/Vsauce (http://www.youtube.com/watch?v=L45Q1_...)

Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space. ~Douglas Adams

Thanks to Dr. Simon O'Toole for talking exoplanets with me! We also discussed the Drake equation but there wasn't really room for it.

Camera by Charles Clement

Music by Kevin McLeod (incompetech.com) Mirage, Scissors

Evidence Facebook's revenue is based on fake likes.
My first vid on the problem with Facebook: http://bit.ly/1dXudqY
I know first-hand that Facebook's advertising model is deeply flawed. When I paid to promote my page I gained 80,000 followers in developing countries who didn't care about Veritasium (but I wasn't aware of this at the time). They drove my reach and engagement numbers down, basically rendering the page useless. I am not the only one who has experienced this. Rory Cellan-Jones had the same luck with Virtual Bagel: http://www.bbc.co.uk/news/technology-18819338

The US Department of State spent $630,000 to acquire 2 million page likes and then realized only 2% were engaged. http://wapo.st/1glcyZo

I thought I would demonstrate that the same thing is still happening now by creating Virtual Cat (http://www.facebook.com/MyVirtualCat). I was surprised to discover something worse - false likes are coming from everywhere, including Canada, the US, the UK, and Australia. So even those carefully targeting their campaigns are likely being duped into spending real money on fake followers. Then when they try to reach their followers they have to pay again.

And it's possible to be a victim of fake likes without even advertising. Pages that end up on Facebook's "International Suggested Pages" are also easy targets for click-farms seeking to diversify their likes. http://tnw.co/NsflrC

Thanks to Henry, Grey, and Nessy for feedback on earlier drafts of this video.

We also made a video about laser cooling! http://bit.ly/PhysGirl
Check out Audible: http://bit.ly/AudibleVe
Check out Beyond Slow Motion: http://bit.ly/VeBeyondSlowMo
More on this topic: http://wke.lt/w/s/ef3eV

Special thanks to Laser Away in Santa Monica for helping make this happen - your staff was awesome! http://bit.ly/VeLaserAway

Research and filming by Raquel Nuno and Aaron White.

Origami is inspiring a plethora of new engineering designs. Try yourself: https://ve42.co/Origami
Thanks Audible! Start listening with a 30-day trial and your first audiobook, plus two Audible Originals free when you go to https://audible.com/veritasium or text veritasium to 500500

Huge thanks to:
Dr. Robert Lang https://langorigami.com
Prof. Larry Howell https://www.compliantmechanisms.byu.edu/

On first glance it's surprising that origami -- a centuries old art of folding paper to achieve particular aesthetics -- is applicable to engineering. But upon closer consideration there are a lot of reasons methods developed for paper folding are also applicable to engineering: origami allows you to take a flat sheet of material and convert it to almost any shape only by folding. Plus for large flat structures, origami provides a way of shrinking dimensions while ensuring simply deployment - this is particularly useful for solar arrays in space applications. Furthermore, motions designed to take advantage of the flexibility of paper can also be used to form compliant mechanisms for engineering like the kaleidocycle. Since the principles of origami are scalable, mechanisms can also be dramatically miniaturized.

Some of the work shown is based upon work supported by the National Science Foundation and the Air Force Office of Scientific Research under Grant No. EFRI-ODISSEI-1240417. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Special thanks to Patreon supporters:
Alfred Wallace, Arjun Chakroborty, Bryan Baker, Chris Vargas, Chuck Lauer Vose, DALE HORNE, Donal Botkin, halyoav, James Knight, Jasper Xin, Joar Wandborg, Kevin Beavers, kkm, Leah Howard, Lyvann Ferrusca, Michael Krugman, Noel Braganza, Pindex, Ron Neal, Sam Lutfi, Stan Presolski, Tige Thorman

Edited by
Jonny Hyman, Isaac Frame, and Derek Muller

Music by
Jonny Hyman

I bought 10,000 shade balls and tried to swim in them. They appear to act like a non-Newtonian fluid: rigid under high shear stress, but they flow like a liquid under low shear.
Get a signed shade ball by supporting Veritasium: https://ve42.co/patreon

Receiving a shade ball:
1. Support Veritasium on any Patreon tier and enter your address https://ve42.co/patreon
2. In about a month I will send out signed shade balls
3. I will cover all shipping costs but if things get really crazy I will prioritize existing Patreon supporters and higher tiers

My sense was that swimming in shade balls would be difficult but still doable. This was roughly true for the single layer of shade balls. The shade balls slide past each other so they act like a liquid, albeit a viscous one owing to their significant inertia. It's much more intense exercise and it's also annoying to be bombarded with shade balls on all sides of your body, particularly your head. With multi-layer shade balls (as exists on much of LA reservoir) things get significantly more difficult. The balls bunch together and when you try to move through them quickly, they become more rigid, providing significant resistance to motion. This has the benefit that you can lie on them and as long as they stay trapped under you, you can float on them. But a little bit of motion causes them to move around and you sink through quickly.

Huge thanks to:
Jordan Schnabel and Cristian Carretero for filming and swimming and providing lifeguard services.
Raquel Nuno for filming and putting up with me.

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.

Music from https://epidemicsound.com "Dubstep Mammoth 2" "Finally Here (Instrumental)" "The Last Arrival" "Sundown Love (Instrumental)"

A song about Gravity set to the tune of John Mayer's Gravity.

Gravity is working with me
And Gravity, keeps me on the ground

All mass attracts all other mass
a force proportional to mass one and two
and inversely to the distance between them squared

Oh, gravity is working with me
and gravity, makes apples fall to ground

Oh twice the mass has twice the pull
but the force on each is still equal
It keeps the moon and the satellites
going round

Oh twice the mass has twice the pull
but the force on each is still equal
It keeps the moon and the satellites
going round

Oh gravity, the force that makes weight on me
Woah, gravity, now general relativity (how can that be?)

The force between us all is
The force between us all is
The force between us all is
Gravity between us all is
Gravity between us all is
Gravity between gravity between us all is

Scientists have combined ultrasound, viruses and synthetic drugs to control regions of the brain.
Check out Skillshare: https://skl.sh/veritasium (first 500 get 2 months free)

Special thanks to Prof. Mikhail Shapiro and Dr. Jerzy Szablowski:
http://shapirolab.caltech.edu

Human brains are complicated - the most complicated thing in the known universe, many people say. So far we understand little - just that certain regions of the brain appear to be involved in certain activities and certain disorders. In extreme cases this has led to the practice of removing sections of the brain, or using electrodes or optical fibers to control activation rates. What is unique about this approach is it offers a way to turn on and off specific brain regions without invasive surgery. It has promise because it combines existing technologies: micro-bubbles, ultrasound, synthetic viruses, and synthetic drugs to achieve this goal.

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 "Experimental1"

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
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1, 2, 3 A song about 'lectricity
because it powers our lives
makes it possible for us to thrive

because it powers our lives
makes it possible for us to thrive

Oh, 4, 5, 6, volts of potential difference
makes electrons go round
if the circuit is complete and sound

Circuit's closed
Voltage There
Current Flows
Power Everywhere

We use AC,
in factories
and homes because we can transform it
High voltage
transmits with lower loss
but low voltage is best for safety
I said what is electricity?

Well, so 1,2,3 a song about 'lectricty
because it powers our lives
makes it possible for us to thrive

because it powers our lives
makes it possible for us to thrive

Oh, 4,5,6 volts of potential difference
makes electrons go round if the circuit is complete and sound

Heat makes steam
turns turbines
and a magnet in
coils of wires

We use AC,
in factories
and homes because we can transform it
High voltage
transmits with lower loss
but low voltage is best for safety
I said what is electricity?

Oh yeah, Oh yeah, C'mon!
How'd it be
no energy
of the electrical persuasion
I know we'd
have no computers
no internet or mobile phones yeah
Powers the world
Makes the world
We need electricity yeah

Objects hang heavy side down, but what happens when you spin an asymmetrically weighted disk - well the heavy part actually rises to the top. Why is this?

Can we really touch things? Well if by touch we mean exchange a force-carrying particle with, then yes. The photon is the force-carrier of the electromagnetic interaction. But if the photon is also a particle of light then why aren't magnets glowing? Because the photons are virtual particles, which means they can't be directly detected (without changing the outcome we are trying to measure.
Supported by Audible: http://bit.ly/ZJ5Q6z
Who would win in a chin-up competition between me and MinutePhysics? What is going to be the most exciting area of scientific discovery in the next few decades? Where can you get a Veritasium t-shirt? http://dft.ba/-vetshirt
Huge thanks to Brady, CGP Grey, and Henry for their cameos.

Thank you to PhET for the Bohr model simulation: http://phet.colorado.edu/

My hypothesis is that the algorithm, rather than viewer preference, drives views on the site. As the algorithm shifts, various YouTubers experience burnout (as what used to work no longer works) and right now click-through rate is the key metric. So clickable titles and thumbnails are the only way to get a lot of impressions and hence views - they are the only way to go viral. This leads me to wonder which audiences will become most prevalent on the site and if there will even be a place for educational content. In the long-term, hopefully YouTube is able to measure satisfaction through surveys and other metrics to ensure an optimal experience for everyone on the site.

Flipchart artwork by Maria Raykova
Filmed by Raquel Nuno
Thumbnail by Ignat Berbeci

I used a nitrogen membrane and Stirling cryocooler to liquefy nitrogen out of the air. For this video I partnered with Starbucks to celebrate their Nitro Cold Brew. Order one here: https://starbucks.app.link/derekmuller

Making liquid nitrogen is hard - in fact up until 150 years ago scientists doubted whether it was even possible to liquefy nitrogen. In 1823, At the royal institution in London, Michael Faraday first produced liquid chlorine, kind of accidentally by putting it under high pressure. He similarly liquefied ammonia.

Borrowing a mixture from Thilorier in France, a combination of dry ice, snow and ether, he reached a temperature of -110C. By 1845 he used this mixture plus a hand pump to pressurize gases to liquefy all the known gases except six, which included oxygen and nitrogen. These became known as the “permanent” gases.

A French Physicist Aimé compressed oxygen and nitrogen in tanks and then lowered them into the ocean over 1.6km deep, where the pressure got up to 200 atmospheres. Still the gases didn’t liquefy.

Only at the end of 1877 were the first droplets of liquid oxygen and liquid nitrogen produced, by Cailletet in France. He first tried oxygen by compressing it up to 300 atmospheres, cooled to -30C, but that wasn't even enough to liquefy oxygen. But when he suddenly released the pressure, the expanding gas cooled, he estimated to -200C and he saw a mist and then droplets slide down the walls of his vessel.

It's amazing how far we've come in that now I can purchase a helium-based cryocooler. It compresses and expands the gas to absorb heat from the tip of the cold finger and eject it into the surroundings at ambient temperature.

Everything is not as it first appears. This simple plastic ball looks purple until you swing it in a circle and reveal its true nature. Inside are three light emitting diodes (LEDs), which are red, green and blue. They turn on and off in sequence very quickly. When still, the ball appears purple because your eyes and brain don't 'refresh' quickly enough to perceive the changing colours. However, when swung in a circle, the ball changes colours at different locations so the colours don't merge with each other and the ball's true nature is revealed. Now let's not think too carefully about how this illusion is conveyed through video (because the camera doesn't refresh quickly enough to perceive the colours changing either - so you have no hope of seeing it on YouTube even frame by frame).