Half of the ordinary baryonic matter has been tough to find but Fast Radio Bursts made it possible to detect the WHIM. Thanks to Kiwico for sponsoring this video! For 20% off go to https://kiwico.com/veritasium or use code VERITASIUM at checkout.

Special thanks to Prof. Geraint Lewis https://ve42.co/gfl

Nature paper: A census of baryons in the Universe from localized fast radio bursts
https://ve42.co/whim

Research and Writing by Max Levy, Derek Muller and Jonny Hyman
Editing, Animations, Audio Mix & Mastering by Jonny Hyman
Filmed by Raquel Nuno
Thumbnail by Ignat Berbeci
Music from Epidemic Sound https://epidemicsound.com

This video is sponsored by Brilliant. The first 200 people to sign up via https://brilliant.org/veritasium get 20% off a yearly subscription. Astronomers think there should be 5 times as much dark matter as ordinary matter – a shadow universe that makes up most of the mass in the universe. But after decades of trying, no experiments have found any trace of dark matter – except one.

A massive thanks to the wonderful people at the ARC Centre of Excellence for Dark Matter Physics https://www.centredarkmatter.org for showing us around and being on camera – Fleur Morrison, A/Prof Phillip Urquijo, Prof Elisabetta Barberio, Madeleine Zurowski and Grace Lawrence.
Thanks to Leo Fincher-Johnson and everyone at the Stawell gold mine for having us.
Massive thanks to Prof. Geraint Lewis – Geraint has been Veritasium’s go-to expert for anything astrophysics and cosmology related. Please check out his website, and buy his books, they’re great – https://www.geraintflewis.com
Thanks to Prof. Timothy Tait for the help to make sure we got the science right.
Thanks to Ingo Berg for illustrating the effect of dark matter on the rotation of a galaxy https://beltoforion.de/en/spir....al_galaxy_renderer/s

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Galaxy cluster simulation from IllustrisTNG – https://www.tng-project.org
Venn Diagram of Dark Matter from Tim Tait – https://ve42.co/venn
The Bullet Cluster Image from Magellan, Hubble and Chandra telescopes – https://ve42.co/BC2
Bullet cluster animation from Andrew Robertson / Institute for Computational Cosmology / Durham University – https://ve42.co/BC3

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Bernabei, R., Belli, P., Cappella, F., Cerulli, R., Dai, C. J., d’Angelo, A., ... & Ye, Z. P. (2008). First results from DAMA/LIBRA and the combined results with DAMA/NaI. The European Physical Journal C, 56(3), 333-355. – https://ve42.co/DAMA2008

Zwicky, F. (1933). Die rotverschiebung von extragalaktischen nebeln. Helvetica physica acta, 6, 110-127. – https://ve42.co/Zwicky1

Zwicky, F. (1937). On the Masses of Nebulae and of Clusters of Nebulae. The Astrophysical Journal, 86, 217. – https://ve42.co/Zwicky2

Rubin, V. C., & Ford Jr, W. K. (1970). Rotation of the Andromeda nebula from a spectroscopic survey of emission regions. The Astrophysical Journal, 159, 379. – https://ve42.co/Rubin1

Bosma, A., & Van der Kruit, P. C. (1979). The local mass-to-light ratio in spiral galaxies. Astronomy and Astrophysics, 79, 281-286. – https://ve42.co/Bosma1

Milgrom, M. (1983). A modification of the Newtonian dynamics as a possible alternative to the hidden mass hypothesis. The Astrophysical Journal, 270, 365-370. – https://ve42.co/mond1

Sanders, R. H., & McGaugh, S. S. (2002). Modified Newtonian dynamics as an alternative to dark matter. Annual Review of Astronomy and Astrophysics, 40(1), 263-317. – https://ve42.co/Mond2

M. Markevitch; A. H. Gonzalez; D. Clowe; A. Vikhlinin; L. David; W. Forman; C. Jones; S. Murray & W. Tucker (2004). "Direct constraints on the dark matter self-interaction cross-section from the merging galaxy cluster 1E0657-56". Astrophys. J. 606 (2): 819–824. – https://ve42.co/BC1

Great website about the CMB – http://background.uchicago.edu..../~whu/intermediate/d

Galli, S., Iocco, F., Bertone, G., & Melchiorri, A. (2009). CMB constraints on dark matter models with large annihilation cross section. Physical Review D, 80(2), 023505. – https://ve42.co/CMB1

Antonello, M., Barberio, E., Baroncelli, T., Benziger, J., Bignell, L. J., Bolognino, I., ... & Xu, J. (2019). The SABRE project and the SABRE Proof-of-Principle. The European Physical Journal C, 79(4), 1-8. – https://ve42.co/SABRE1


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Special thanks to Patreon supporters: Inconcision, Kelly Snook, TTST, Ross McCawley, Balkrishna Heroor, Chris LaClair, Avi Yashchin, John H. Austin, Jr., OnlineBookClub.org, Dmitry Kuzmichev, Matthew Gonzalez, Eric Sexton, john kiehl, Anton Ragin, Diffbot, Micah Mangione, MJP, 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, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Stephen Wilcox, Marinus Kuivenhoven, Clayton Greenwell, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal

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Written by Derek Muller and Petr Lebedev
Edited by Trenton Oliver
Animation by Ivy Tello and Mike Radjabov
Filmed by Derek Muller and Petr Lebedev
Additional video/photos supplied by Getty Image
B-roll supplied by Stawell Gold Mine
Music from Epidemic Sound
Thumbnail by Ignat Berbeci
Produced by Derek Muller, Petr Lebedev, and Emily Zhang

Kodak detected the first atomic bomb before anyone else figured it out. Then they made a deal not to tell anyone. Thanks to HBO Max, and their new show raised by Wolves for sponsoring this video! https://rb.gy/alghwn

Thanks to Uranium: Twisting the Dragon's Tail for the opening clip: https://www.pbs.org/show/urani....um-twisting-dragons-

References:
Albuquerque Tribune Bulletin, July 16, 1945 – https://www.marshallfoundation.....org/library/documen

Webb, J. H. (1949). The fogging of photographic film by radioactive contaminants in cardboard packaging materials. Physical Review, 76(3), 375.

Julian Webb at Oak Ridge – Snavely, B. B. (1989). Julian H. Webb. PhT, 42(7), 87.https://physicstoday.scitation.....org/doi/pdf/10.1063

Radium in watch dials – https://www.epa.gov/radtown/radioactivity-antiques

A 1958 video about how Kodak film is made, noting the careful monitoring of radioactive contaminants – https://www.youtube.com/watch?v=9qjBJOFImaU&t=597s&ab_channel=OwenMorgan

Radioactive fallout in 1951 - https://www.nytimes.com/1951/0....2/03/archives/increa

1998 senate hearing – https://www.govinfo.gov/conten....t/pkg/CHRG-105shrg44

Institute of Medicine and National Research Council. 1999. Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests: Review of the National Cancer Institute Report and Public Health Implications. Washington, DC: The National Academies Press. https://doi.org/10.17226/6283. https://www.cancer.gov/about-c....ancer/causes-prevent

Baby Teeth Survey – Reiss, L. Z. (1961). Strontium-90 absorption by deciduous teeth. Science, 134(3491), 1669-1673.

Strontium 90 and Cancer rates – Gould, J. M., Sternglass, E. J., Sherman, J. D., Brown, J., McDonnell, W., & Mangano, J. J. (2000). Strontium-90 in deciduous teeth as a factor in early childhood cancer. International Journal of Health Services, 30(3), 515-539.

Wine forensics – Hubert, P., Perrot, F., Gaye, J., Médina, B., & Pravikoff, M. S. (2009). Radioactivity measurements applied to the dating and authentication of old wines. Comptes Rendus Physique, 10(7), 622–629. doi:10.1016/j.crhy.2009.08.007

Strontium 90 in forensics – Maclaughlin-Black, S. M., Herd, R. J., Willson, K., Myers, M., & West, I. E. (1992). Strontium-90 as an indicator of time since death: a pilot investigation. Forensic science international, 57(1), 51-56.

Research and Writing by Derek Muller, Petr Lebedev, and Jonny Hyman

Filmed and edited by Derek Muller
Animations by Ivy Tello and Jonny Hyman
Music by Jonny Hyman
Additional Music from:
Epidemic Sound https://epidemicsound.com "Seaweed"
Kevin MacLeod https://incompetech.com "Lightless dawn"
Craig Conrad https://www.craigconard.com/royaltyfree "ASTRAL"

Celsius never devised nor used the scale that now bears his name.

Veritasium is now on Patreon: http://patreon.com/veritasium

Special thanks to Michael Stevens of Vsauce! http://youtube.com/vsauce1

More info about Celsius and temperature scales: http://wke.lt/w/s/2I6Nu

References for this video:

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

Special Thanks to the Uppsala University Museum
I filmed this in Uppsala in the summer of 2012! So I've been thinking about this idea for a very long time. I'm glad to finally have it out there in the world.

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 Ivy Tello
Vitamania was written, directed and produced by Sonya Pemberton

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

A head-vaporizing laser with a perfect wavelength detecting sub-proton space-time ripples.
Huge thanks to Prof Rana Adhikari and LIGO: http://ligo.org
Here's how he felt when he learned about the first ever detection: https://youtu.be/ViMnGgn87dg

Thanks to Patreon supporters:
Nathan Hansen, Donal Botkin, Tony Fadell, Saeed Alghamdi, Zach Mueller, Ron Neal
Support Veritasium on Patreon: http://bit.ly/VePatreon

A lot of videos have covered the general overview of the discovery of gravitational waves, what they are, the history of the search, when they were found but I wanted to delve into the absurd science that made the detection possible.

When scientists want one megawatt of laser power, it's not just for fun (though I'm sure it's that too), it's because the fluctuations in the number of photons is proportional to their square root, making more powerful beams less noisy (as a fraction of their total). The smoothest mirrors were created not for aesthetic joy but because when you're trying to measure wiggles that are a fraction the width of a proton, a rough mirror surface simply won't do.

Filmed by Daniel Joseph Files

Music by Kevin MacLeod, http://www.incompetech.com "Black Vortex" (appropriately named)

Music licensed from Epidemic Sound http://epidemicsound.com "Observations 2" (also appropriately named)

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

A pulsing black hole in the centre of a distant galaxy sheds light on black hole and galaxy formation. How fast are black holes rotating and how does that rotation change over its life-span?

Huge thanks to Prof. Geraint Lewis and study author Dr. Dheeraj Pasham.

A loud quasi-periodic oscillation after a star is disrupted
by a massive black hole
https://ve42.co/pasham

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

Music from http://epidemicsound.com "Colorful animation 4" "serene story 2" "To the stars 01" "Black Vortex

Animations by Alan Chamberlain and courtesy of NASA

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

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

Does quantum entanglement make faster-than-light communication possible?
What is NOT random? http://bit.ly/NOTrandoVe
First, I know this video is not easy to understand. Thank you for taking the time to attempt to understand it. I've been working on this for over six months over which time my understanding has improved. Quantum entanglement and spooky action at a distance are still debated by professors of quantum physics (I know because I discussed this topic with two of them).

Does hidden information (called hidden variables by physicists) exist? If it does, the experiment violating Bell inequalities indicates that hidden variables must update faster than light - they would be considered 'non-local'. On the other hand if you don't consider the spins before you make the measurement then you could simply say hidden variables don't exist and whenever you measure spins in the same direction you always get opposite results, which makes sense since angular momentum must be conserved in the universe.

Everyone agrees that quantum entanglement does not allow information to be transmitted faster that light. There is no action either detector operator could take to signal the other one - regardless of the choice of measurement direction, the measured spins are random with 50/50 probability of up/down.

Special thanks to:
Prof. Stephen Bartlett, University of Sydney: http://bit.ly/1xSosoJ
Prof. John Preskill, Caltech: http://bit.ly/1y8mJut

Looking Glass Universe: http://bit.ly/17zZH7l
Physics Girl: http://bit.ly/PhysGirl
MinutePhysics: http://bit.ly/MinPhys
Community Channel: http://bit.ly/CommChannel
Nigel, Helen, Luke, and Simon for comments on earlier drafts of this video.

Filmed in part by Scott Lewis: http://google.com/+scottlewis

Music by Amarante "One Last Time": http://bit.ly/VeAmarante

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.

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

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

I have the photic sneeze reflex so I sneeze when I look at bright light.
Check out 23andMe: http://ve42.co/23andme
*So technically the single nucleotide swap (C instead of T) is not actually in a gene per se but in an intergenic region on chromosome 2. It's also not clear exactly how this affects physiology or causes the sun sneeze but there is correlative evidence that every copy of this single nucleotide polymorphism (SNP) is associated with a 1.3x increase in likelihood of having the photic sneeze reflex.

I have wanted to make a video about sun-sneezing for a long time. It is something I've experienced my whole life. When I go from a dark room indoors into full sunlight I invariably sneeze. I thought everyone did it. So my original question was why do people sneeze when they see bright light? That led me to consider what possible evolutionary advantages there could be to sneezing in sunlight. The obvious advantage to me is that sunlight kills pathogens of which there may be many in your snot or mucus. So sneezing in sunshine is a much better idea than sneezing inside a dark, damp cave where you may be living.

For more info, check out:
Web-Based, Participant-Driven Studies Yield Novel Genetic Associations for Common Traits
http://journals.plos.org/plosg....enetics/article?id=1

Filmed by Raquel Nuno

Hope this was worth the wait! So many people helped with this video: Prof John Sperry, Hank Green, Henry Reich, CGP Grey, Prof Poliakoff, my mum filmed for me in beautiful Stanley Park and Jen S helped with the fourth version of the script.

Prof John Sperry http://biologylabs.utah.edu/sperry/john.html
Hank Green (SciShow) http://www.youtube.com/user/scishow
Henry Reich (minutephysics) http://www.youtube.com/user/minutephysics
CGP Grey http://www.youtube.com/user/cgpgrey
Prof Poliakoff (Periodic Videos) http://www.youtube.com/user/periodicvideos

Also thanks to the Palais de la Decouverte - they helped me with the whole vacuum pump setup in Paris. No, I could not actually suck water up 10m - I did about 4m, but the vacuum pump was easily able to do it and I saw spontaneous boiling on all of our various trials. Footage from this may end up on 2Veritasium.

Trees create immense negative pressures of 10's of atmospheres by evaporating water from nanoscale pores, sucking water up 100m in a state where it should be boiling but can't because the perfect xylem tubes contain no air bubbles, just so that most of it can evaporate in the process of absorbing a couple molecules of carbon dioxide. Now I didn't mention the cohesion of water (that it sticks to itself well) but this is implicit in the description of negative pressure, strong surface tension etc.

Can you figure out the rule?
Did you see the exponents pattern? http://youtu.be/AVB8vRC6HIY
Why do you make people look stupid? http://bit.ly/12Fmlpl

How do you investigate hypotheses? Do you seek to confirm your theory - looking for white swans? Or do you try to find black swans? I was startled at how hard it was for people to investigate number sets that didn't follow their hypotheses, even when their method wasn't getting them anywhere.

In the video I say "when people came to Australia..." by which I meant, "when Europeans who believed all swans were white came to Australia..." I did not mean any offence to Indigenous Australians who were already in Australia at that time. Please accept my apologies for the poor phrasing if you were offended by it.

This video was inspired by The Black Swan by Nassim Taleb and filmed by my mum. Thanks mum!

Partly my motivation came from responses to my Facebook videos - social media marketers saying 'Facebook ads have worked for me so there can't be fake likes.' Just because you have only seen white swans, doesn't mean there are no black ones. And in fact marketers are only looking for white swans. They think it was invalid of me to make the fake Virtual Cat page: 'well of course if it's a low quality page you're going to get low quality likes.' But my point is this is black swan bait, something they would never make because their theory is confident in the exclusive existence of white swans.

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

Yes, I have made a similar vid before. This is the Australian TV version for the ABC show Catalyst http://www.abc.net.au/catalyst/
Misconceptions About Temperature http://www.youtube.com/watch?v=vqDbMEdLiCs
The Mysterious Falling Slinky http://www.youtube.com/watch?v=mAA613hqqZ0
Why Are Astronauts Weightless? http://www.youtube.com/watch?v=iQOHRKKNNLQ

And for those of you wanting a more General Relativity based explanation. Don't worry, it's coming.

For more on spin, check out: http://youtu.be/v1_-LsQLwkA
This video was supported by TechNYou: http://bit.ly/19bBX5G
A quantum computer works in a totally different way from a classical computer. Quantum bits or 'qubits' can exist in a superposition state of both zero and one simultaneously. This means that a set of two qubits can be in a superposition of four states, which therefore require four numbers to uniquely identify the state. So the amount of information stored in N qubits is two to the power of N classical bits.

Thank you to Andrea Morello and UNSW. For more info, check out: http://bit.ly/17wZ7lt