*Watch with headphones on!
Is 45 minutes really the longest anyone can stay in a perfectly silent, pitch-black room?
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Want to watch the whole hour of silence? http://youtu.be/jr1UMFC9DV0
Many stories have circulated claiming the longest anyone has stayed in an ultra-quiet anechoic chamber is 45 minutes, the reason being any longer would drive you insane. To me this sounded like unsubstantiated rubbish, like the claim the Great Wall is the only manmade structure visible from space. So I put my own psyche on the line, subjecting myself to over an hour of the most intense quiet on Earth. No, this was not THE quietest room on Earth (-9dB) but it is one of the quietest, and the truth is once you put a person inside, they are by far the loudest thing in there so the sound rating of the room is irrelevant.
I was not surprised to find that I could stay in there for as long as I liked and feel perfectly fine. What was surprising is that my heartbeat was audible. You can hear it on the sound recording. Now I wasn't consciously aware of the sound of my heart while in the room, but I was more aware of the feeling of it beating.
Huge thank you to everyone at BYU: Duane Merrell, Spencer Perry, Cameron Vongsawad, Jazz Myers, Ann Clawson, and Robert Willes.
The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram. Support Veritasium on Patreon: http://bit.ly/VePatreon A kilogram isn't what it used to be. Literally. The original name for it was the 'grave', proposed in 1793 but it fell victim to the French Revolution like its creator, Lavoisier. So begins the tale of the most unusual SI unit. The kilogram is the only base unit with a prefix in its name, and the only one still defined by a physical artifact, the international prototype kilogram or IPK. But the problem with this definition has long been apparent. The IPK doesn't seem to maintain its mass compared to 40 similar cylinders minted at the same time. The goal is therefore to eliminate the kilogram's dependence on a physical object. Two main approaches are being considered to achieve this end: the Avogadro Project and the Watt Balance. The Avogadro project aims to redefine Avogadro's constant (currently defined by the kilogram -- the number of atoms in 12 g of carbon-12) and reverse the relationship so that the kilogram is precisely specified by Avogadro's constant. This method required creating the most perfect sphere on Earth. It is made out of a single crystal of silicon 28 atoms. By carefully measuring the diameter, the volume can be precisely specified. Since the atom spacing of silicon is well known, the number of atoms in a sphere can be accurately calculated. This allows for a very precise determination of Avogadro's constant. Special thanks to Katie Green, Dr. David Farrant, the CSIRO, and the National Measurment Institute for their help. Thanks also to Nessy Hill for filming and reviewing earlier drafts of this video. There is debate as to whether this is truly the roundest object ever created. The Gravity Probe-B rotors are also spherical with very low tolerances such that they may in fact be rounder. Music by Kevin McLeod (incompetech.com) Decision, Danse Macabre, Scissors
The Mathologer puts the latest $2000 addition to his Klein bottle collection to work. A couple of first-ever fun mathematical stunts in this video. This video finishes with a puzzle for you to think about. We posted a video with the solution on 1 August 2015: https://youtu.be/ZMC61C5tigA Enjoy! Burkard Polster and Giuseppe Geracitano P.S.: Most of of Burkard's glass Klein bottles as well as the Klein bottle hat were made by Cliff Stoll of ACME Klein bottles (www.kleinbottle.com). The metal 3d-printed Klein bottle opener was made by Bathsheba Grossman (www.bathsheba.com).
These are a few clips from the Metallica episode of Time Warp that shows some musical instruments in slow motion. Time Warp is a popular science television program produced for the Discovery Channel in the United States, in which MIT scientist, teacher, and artist Jeff Lieberman along with high speed camera expert Matt Kearney, turn their high speed camera on everyday occurrences and singular talents. This video shows in slow motion: - James Hetfield singing, showing the inevitable spitting, and smashing two electric guitars. - Acoustic guitar playing an octave. - Kirk Hammett playing the hammer-on and pull-off techniques in the electric guitar. - Violin playing a fifth. - Robert Trujillo showing the gallop and slap bass techniques in the electric bass. - Lars Ulrich in the drum kid, showing the snare drum from the inside and the cymbals. - Piano strings.
How much information is there in Spanish vs English, you vs the world? Check out Audible: http://bit.ly/AudibleVe Huge thanks to all the amazing people who made this possible: Christina Ochoa - Spanish https://twitter.com/christina_ochoa Vanessa Hill - Filming https://www.youtube.com/braincraftvideo Henry Reich - Filming, cameo http://youtube.com/minutephysics Cara Santa Maria - Set design http://carasantamaria.com Michael Stevens - cameo http://youtube.com/vsauce Crystal Dilworth - consultation https://twitter.com/PolycrystalhD Thanks also to MinutePhysics for wardrobe and lending the use of the amazing "Things to do when it's really cold outside" video: https://www.youtube.com/watch?v=j3Gs6tyiNX4 More on this theme to come in the main collaboration with Vsauce.
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