Veritasium

Oct 09 2020 14 mins 54

An element of truth - videos about science, education, and anything else I find interesting.










How Kodak Exposed The Atomic Bomb
Sep 16 2020 13 mins  
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/uranium-twisting-dragons-tail/ References: Albuquerque Tribune Bulletin, July 16, 1945 – https://www.marshallfoundation.org/library/documents/albuquerque-tribune-bulletin-16-july-1945/ 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/10.1063/1.2811100 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/1951/02/03/archives/increased-radiation-found-in-east-laid-to-atom-tests-held-harmless.html?searchResultPosition=20 1998 senate hearing – https://www.govinfo.gov/content/pkg/CHRG-105shrg44045/html/CHRG-105shrg44045.htm 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-cancer/causes-prevention/risk/radiation/i131-report-and-appendix 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 Iván 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"




Is Dust Mostly Dead Skin?
Aug 04 2020 15 mins  
People claim that 70-80% of household dust is dead skin, but is it true? Thanks to Google for sponsoring this video! Learn more about Search here: https://www.google.com/search/howsearchworks/ Special thanks to J.M.E.H van Bronswijk, author of 'House Dust Biology'. We exchanged emails to make sure I got my facts straight for this video. Below is an excerpt from her email to me, responding to my claims that start with a dash: - Around half of airborne dust particles under 100um are skin scales This is true for climates, regions and seasons where people live mostly indoors. The 1 to 2 g of skin scales shed each 24 hours will end up in places where people are present (and rub their skin or have textile moving over the skin). You can also look at it from a different angle: What else has the same size and could contribute? That will usually be pollen from outdoor sources, also depending on season, region and climate, as well as the ventilation regime of the building. However, taken as the median value over a whole year, I consider your statement correct for regions with a temperate climate. - 53% of dust particles vacuumed from a mattress were found to be skin scales It depends a little on the type of mattress. For polyether mattresses the amount may even be larger. For mattresses made of natural material it could be less since the mattress-material will also give off small particles. - larger particles consist mostly of fibers, eg. cotton, paper, wool, synthetics That's true .. including bread crumbs ..... 🙂 - skin scales seem to form a larger fraction of dust where we spend more time, e.g. in or near bed. ..... and on the couch used to view television or be active in gaming. It has to do with the constant production of skin scales over the 24 hours. - skin scales form a smaller fraction of dust if there are significant other sources, e.g. carpeting, dirt from outside etc. Yes, everyting you walk on with your shoes or that recieves dirt from the outside with other means, will have a lessr percentage of human skin scales. However, do not forget the skin scales of pets that will also be an active allergen for many people, and a food source for house dust mites. Information on dust particle size ©ISO. This material is adapted from ISO 7708:1995, with permission of the American National Standards Institute (ANSI) on behalf of the International Organization for Standardization. All rights reserved. Research and Writing by AJ Fillo and Derek Muller Editing, Audio Mix & Master, and Computer animations by Jonny Hyman Dust and character animation by Ivan Tello Filming by Raquel Nuno Thumbnail by Fictionalhead https://www.youtube.com/fictionalhead Intro Music composed by Jonny Hyman Additional Music from Epidemic Sound: Colored Spirals, Observations






Turbulent Flow is MORE Awesome Than Laminar Flow
May 15 2020 18 mins  
Everyone loves laminar flow but turbulent flow is the real MVP. A portion of this video was sponsored by Cottonelle. Purchase Cottonelle Flushable Wipes and try them for yourself: https://bit.ly/2WJm9Hq Special thanks to: Prof. Beverley McKeon and team https://www.mckeon.caltech.edu Destin from Smarter Every Day https://www.youtube.com/smartereveryday Nicole Sharp from FYFD https://ve42.co/fyfd Pavol Dobryakov turbulent simulations: https://paveldogreat.github.io/WebGL-Fluid-Simulation/ I got into turbulent flow via chaos. The transition to turbulence sometimes involves a period doubling. Turbulence itself is chaotic motion, it is unpredictable and sensitively dependent on initial conditions. What surprised me is all the ways turbulent flow is useful to us. It is diffusive, meaning it causes mixing. This is useful in jet engines or rocket nozzles (which Destin studies) and is important to achieve in microfluidic devices, which are so small that turbulent flow is actually difficult to achieve. Turbulent flow can energize a boundary layer, which is important to maintain flow attachment over a wing, maintaining lift and delaying stall. Similarly a turbulent boundary layer over a golf ball reduces pressure drag allowing golf balls to fly further. This is the reason for the dimples on golf balls. Flow transitioning to turbulence in the wake of a bluff body can create periodic vortex shedding. This beautiful phenomenon can be seen in the von Kàrmàn vortex street in clouds viewed from space. Turbulence is everywhere, in the air currents in a room, in your aorta, in the breaths you exhale, in oil pipelines and water pipes, in the flow over cars and ships and planes. Animals have evolved for it (like dead fish swimming up stream) and we have engineered our environment, our planes and golf balls for it. Laminar flow may be nice to look at (which is why we use it in decorative fountains) but turbulent flow does the real lifting. Animations by: Jonny Hyman (Sun, Jupiter, Reynolds, airfoil, Earth time-lapse) Research and writing: AJ Fillo and Derek Muller. AJ also created the wind tunnel golf ball shots Filmed by: Daniel Bydlowski and Derek Muller Additional footage: Images of Jupiter courtesy of NASA Turbulence in air currents by the Physics Girl, Dan Walsh, and Grant Sanderson https://youtu.be/N7d_RWyOv20 https://youtu.be/_UoTTq651dE Music: illBird "Shaffuru" https://youtu.be/5rkt53fNMgc From EpidemicSound https://epidemicsound.com "Seaweed" "Colorful Animation 4" Kevin MacLeod https://incompetech.com "Sneaky Adventure"


Parallel Worlds Probably Exist. Here’s Why
Mar 04 2020 20 mins  
The most elegant interpretation of quantum mechanics is the universe is constantly splitting A portion of this video was sponsored by Norton. Get up to 60% off the first year (annually billed) here: https://bit.ly/32SM0yd or use promo code VERITASIUM Special thanks to: Prof. Sean Carroll https://www.preposterousuniverse.com His book, a major source for this video is 'Something Deeply Hidden: Quantum Worlds and The Emergence of Spacetime' Code for solving the Schrödinger equation by Jonny Hyman available here: https://github.com/jonnyhyman/QuantumWaves I learned quantum mechanics the traditional 'Copenhagen Interpretation' way. We can use the Schrödinger equation to solve for and evolve wave functions. Then we invoke wave-particle duality, in essence things we detect as particles can behave as waves when they aren't interacting with anything. But when there is a measurement, the wave function collapses leaving us with a definite particle detection. If we repeat the experiment many times, we find the statistics of these results mirror the amplitude of the wave function squared. Hence the Born rule came into being, saying the wave function should be interpreted statistically, that our universe at the most fundamental scale is probabilistic rather than deterministic. This did not sit well with scientists like Einstein and Schrödinger who believed there must be more going on, perhaps 'hidden variables'. In the 1950's Hugh Everett proposed the Many Worlds interpretation of quantum mechanics. It is so logical in hindsight but with a bias towards the classical world, experiments and measurements to guide their thinking, it's understandable why the founders of quantum theory didn't come up with it. Rather than proposing different dynamics for measurement, Everett suggests that measurement is something that happens naturally in the course of quantum particles interacting with each other. The conclusion is inescapable. There is nothing special about measurement, it is just the observer becoming entangled with a wave function in a superposition. Since one observer can experience only their own branch, it appears as if the other possibilities have disappeared but in reality there is no reason why they could not still exist and just fail to interact with the other branches. This is caused by environmental decoherence. Schrodinger's cat animation by Iván Tello Wave functions, double slit and entanglement animation by Jonny Hyman Filming of opening sequence by Casey Rentz Special thanks to Mithuna Y, Raquel Nuno and Dianna Cowern for feedback on the script Music from https://epidemicsound.com "Experimental 1" "Serene Story 2" "Seaweed" "Colorful Animation 4"


This equation will change how you see the world (the logistic map)
Jan 29 2020 18 mins  
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/ShawRobertDrippingFaucetAsAModelChaoticSystem1984_201811/mode/2up 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/jphyslet:01982004307021100. 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"





How to Slow Aging (and even reverse it)
Dec 13 2019 21 mins  
Scientists like Prof Sinclair have evidence of speeding up, slowing, and even reversing aging. Thanks to LastPass for sponsoring this video. Click here to start using LastPass: https://ve42.co/VeLP What causes aging? According to Professor David Sinclair, it is a loss of information in our epigenome, the system of proteins like histones and chemical markers like methylation that turn on and off genes. Epigenetics allow different cell types to perform their specific functions - they are what differentiate a brain cell from a skin cell. Our DNA is constantly getting broken, by cosmic rays, UV radiation, free radicals, x-rays and regular cell division etc. When our cells repair that damage, the epigenome is not perfectly reset. And hence over time, noise accumulates in our epigenome. Our cells no longer perform their functions well. To counter this decline, we can activate the body's own defenses against aging by stressing the body. Eat less, eat less protein, engage in intense exercise, experience uncomfortable cold. When the body senses existential threats it triggers longevity genes, which attempt to maintain the body to ensure its survival until good times return. This may be the evolutionary legacy of early bacteria, which established these two modes of living (repair and protect vs grow and reproduce). Scientists are uncovering ways to mimic stresses on the body without the discomfort of fasting. Molecules like NMN also trigger sirtuins to monitor and repair the epigenome. This may slow aging. Reversing aging requires an epigenetic reset, which may be possible using Yamanaka factors. These four factors can revert an adult cell into a pluripotent stem cell. Prof. Sinclair used three of the four factors to reverse aging in the retinal cells of old mice. He found they could see again after the treatment. Special thanks to: Professor David Sinclair, check out his book "Lifespan: Why We Age & Why We Don't Have To" Assistant Professor David Gold Noemie Sierra (for polyp images) Genepool Productions for telomere animations from Immortal: https://ve42.co/immortal Epigenetics animations (DNA, histones, methylation etc) courtesy of: http://wehi.tv Animation: Etsuko Uno Art and Technical Direction: Drew Berry Sound Design: Francois Tetaz & Emma Bortignon Scientific Consultation: Marnie Blewitt Courtesy of Walter and Eliza Hall Institute of Medical Research Filming, editing and animation by Jonny Hyman and Derek Muller Music from https://epidemicsound.com "Clearer Views" "Innovations" "A Sound Foundation" "Seaweed" Additional music by Kevin MacLeod from https://incompetech.com "Marty Gots a Plan"


The Science Behind the Butterfly Effect
Dec 06 2019 12 mins  
Chaos theory means deterministic systems can be unpredictable. Thanks to LastPass for sponsoring this video. Click here to start using LastPass: https://ve42.co/VeLP Animations by Prof. Robert Ghrist: https://ve42.co/Ghrist Want to know more about chaos theory and non-linear dynamical systems? Check out: https://ve42.co/chaos-math Butterfly footage courtesy of Phil Torres and The Jungle Diaries: https://ve42.co/monarch Solar system, 3-body and printout animations by Jonny Hyman Some animations made with Universe Sandbox: https://universesandbox.com/ Special thanks to Prof. Mason Porter at UCLA who I interviewed for this video. I have long wanted to make a video about chaos, ever since reading James Gleick's fantastic book, Chaos. I hope this video gives an idea of phase space - a picture of dynamical systems in which each point completely represents the state of the system. For a pendulum, phase space is only 2-dimensional and you can get orbits (in the case of an undamped pendulum) or an inward spiral (in the case of a pendulum with friction). For the Lorenz equations we need three dimensions to show the phase space. The attractor you find for these equations is said to be strange and chaotic because there is no loop, only infinite curves that never intersect. This explains why the motion is so unpredictable - two different initial conditions that are very close together can end up arbitrarily far apart. Music from https://epidemicsound.com "The Longest Rest" "A Sound Foundation" "Seaweed"






Engineering with Origami
Oct 04 2019 18 mins  
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


The Bizarre Behavior of Rotating Bodies, Explained
Sep 18 2019 14 mins  
Spinning objects have strange instabilities known as The Dzhanibekov Effect or Tennis Racket Theorem - this video offers an intuitive explanation. Part of this video was sponsored by LastPass, click here to find out more: https://ve42.co/LP References: Prof. Terry Tao's Math Overflow Explanation: https://ve42.co/Tao The Twisting Tennis Racket Ashbaugh, M.S., Chicone, C.C. & Cushman, R.H. J Dyn Diff Equat (1991) 3: 67. https://doi.org/10.1007/BF01049489 Janibekov’s effect and the laws of mechanics Petrov, A.G. & Volodin, S.E. Dokl. Phys. (2013) 58: 349. https://doi.org/10.1134/S1028335813080041 Tumbling Asteroids Prave et al. https://doi.org/10.1016/j.icarus.2004.07.021 The Exact Computation of the Free Rigid Body Motion and Its Use in Splitting Methods SIAM J. Sci. Comput., 30(4), 2084–2112 E. Celledoni, F. Fassò, N. Säfström, and A. Zanna https://doi.org/10.1137/070704393 Animations by Iván Tello and Isaac Frame Special thanks to people who discussed this video with me: Astronaut Don Pettit Henry Reich of MinutePhysics Grant Sanderson of 3blue1brown Vert Dider (Russian YouTube channel) Below is a further discussion by Henry Reich that I think helps summarize why axes 1 and 3 are generally stable while axis 2 is not: In general, you might imagine that because the object can rotate in a bunch of different directions, the components of energy and momentum could be free to change while keeping the total momentum constant. However, in the case of axis 1, the kinetic energy is the highest possible for a given angular momentum, and in the case of axis 3, the kinetic energy is the lowest possible for a given angular momentum (which can be easily shown from conservation of energy and momentum equations, and is also fairly intuitive from the fact that kinetic energy is proportional to velocity squared, while momentum is proportional to velocity - so in the case of axis 1, the smaller masses will have to be spinning faster for a given momentum, and will thus have more energy, and vice versa for axis 3 where all the masses are spinning: the energy will be lowest). In fact, this is a strict inequality - if the energy is highest possible, there are no other possible combinations of momenta other than L2=L3=0, and vice versa for if the energy is the lowest possible. Because of this, in the case of axis 1 the energy is so high that there simply aren't any other possible combinations of angular momentum components L1, L2 and L3 - the object would have to lose energy in order to spin differently. And in the case of axis 3, the energy is so low that there likewise is no way for the object to be rotating other than purely around axis 3 - it would have to gain energy. However, there's no such constraint for axis 2, since the energy is somewhere in between the min and max possible. This, together with the centrifugal effects, means that the components of momentum DO change.


Does Planet 9 Exist?
Sep 13 2019 16 mins  
A planet has been predicted to orbit the sun with a period of 10,000 years, a mass 5x that of Earth on a highly elliptical and inclined orbit. What evidence supports the existence of such a strange object at the edge of our solar system? Huge thanks to: Prof. Konstantin Batygin, Caltech Prof. David Jewitt, UCLA I had heard about Planet 9 for a long time but I wondered what sort of evidence could support the bold claim: a planet at the very limits of our ability to detect one, so far out that its period is over 60 times that of Neptune. The planet 9 hypothesis helps explain clustering of orbits of distant Kuiper belt objects. It also explains how some of these objects have highly inclined orbits - up to 90 degrees relative to the plane of the solar system. Some are orbiting in reverse. Plus their orbits are removed from the orbit of Neptune, the logical option for a body that could have ejected them out so far. The fact that the perihelion is so far out suggests another source of gravity was essential for their peculiar orbits. Special Thanks to Patreon Supporters: Alfred Wallace, Arjun Chakroborty, Bryan Baker, Chris Vargas, Chuck Lauer Vose, DALE HORNE, Donal Botkin, Eric Velazquez, halyoav, James Knight, Jasper Xin, Joar Wandborg, Kevin Beavers, kkm, Leah Howard, Lyvann Ferrusca, Michael Krugman, Mohammed Al Sahaf, Noel Braganza, Pindex, Ron Neal, Sam Lutfi, Stan Presolski, Tige Thorman Music from http://epidemicsound.com "Observations - From Now On" "Magnified XY"



Flamethrower vs Aerogel
Aug 31 2019 13 mins  
We put aerogel to the test vs 'not-a-flamethrower', a huge 2000°C flame to a large fiberglass blanket infused with silica aerogel - formerly the lightest solid (that title is now held by graphene aerogel). Special thanks to: Aerogel Technologies: https://ve42.co/aerogeltech Aspen Aerogels: https://ve42.co/aspen Ben: @BenScho999999 Dr. Stephen Steiner and the Aerogel Technologies team The footage of aerogel materials in cold environments was provided courtesy of Aspen Aerogels. Their product, cryogel, was shown to be flexible in liquid nitrogen while preventing cold burns to the hand. They are the manufacturer of the blanket used in the main portion of this video. This is the finale of my three-part series on aerogel. I'll put links to the other parts below: World's Lightest Solid: https://youtu.be/AeJ9q45PfD0 I Waterproofed Myself With Aerogel: https://youtu.be/GcdB5bFwio4 Huge thanks to Patreon supporters: Alfred Wallace, Arjun Chakroborty, Bryan Baker, Chris Vargas, Chuck Lauer Vose, Dale Horne, Donal Botkin, Eric Velazquez, halyoav, James Knight, Jasper Xin, Joar Wandborg, Kevin Beavers, kkm, Leah Howard, Lyvann Ferrusca, Michael Krugman, Mohammed Al Sahaf, Noel Braganza, Philipp Volgger, Pindex, Ron Neal, Sam Lutfi, Stan Presolski, Tige Thorman This is an educational video demonstrating scientific experiments performed by professionals. It should not be attempted by viewers. Music from Epidemic Sound: http://epidemicsound.com "Running Against the Clock" "Dangerous Forests"


Making Liquid Nitrogen From Scratch!
Aug 16 2019 13 mins  
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.


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