The General Theory of Relativity tells us gravity is not a force, gravitational fields don’t exist. Objects tend to move on straight paths through curved spacetime. Thanks to Caséta by Lutron for sponsoring this video. Find out more at: https://www.lutron.com/veritasium
Huge thanks to Prof. Geraint Lewis for hours of consulting on this video so I could get these ideas straight in my own brain. Check out his YouTube channel: https://ve42.co/gfl or his books: https://ve42.co/GFLbooks
Amazing VFX, compositing, and editing by Jonny Hyman
2D animations by Ivy Tello
Filmed by Steven Warren and Raquel Nuno
Special thanks to Petr Lebedev for reviews and script consultation
Music by Jonny Hyman and from Epidemic Sound https://epidemicsound.com
Rocket made by Goodnight and Co.
Screen images in rocket by Geoff Barrett
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
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
In a competitive world, tiny advantages can make all the difference. Get 10% off Snatoms with code ‘giveluck’ in the US: https://ve42.co/USA or International: https://snatoms.com
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This video was inspired by and draws examples from the book “Success and Luck: Good Fortune and the Myth of Meritocracy” by Robert H. Frank
Special thanks to Patreon supporters (and to everyone who commented on an earlier version of this video):
Marc Forand, Robert Dickerson, Christian Stauffer, LoadTooSlow, Vincent, Lyvann Ferrusca, DALE HORNE, Alfred Wallace, Kevin Beavers, Arjun Chakroborty, Joar Wandborg, Clayton Greenwell, Michael Krugman, Ron Neal, Donal Botkin
People claim that 70-80% of household dust is dead skin, but is it true?
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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.
Research and Writing by AJ Fillo and Derek Muller
Editing, Audio Mix & Master, and Computer animations by Jonny Hyman
Dust and character animation by Ivy 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
This was a pretty extraordinary experience – thanks to NASA for inviting me! The Atlas V 541 rocket took off carrying the Perseverance rover and Ingenuity the Mars helicopter at 7:50 am July 30, 2020. They should arrive in about seven months on February 18, 2021
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
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.
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’
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 Ivy 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”
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…
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.
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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”
Common pitfalls of New Year’s resolutions and how I plan to avoid them.
Thanks to Simone Giertz for sending me and Every Day Calendar!
Order here: https://everydaycalendar.co
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Scientists like Prof Sinclair have evidence of speeding up, slowing, and even reversing aging.
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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
