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1
World's Roundest Object!
by Veritasium
5,376,708 views
The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram.
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 -
2
The Most Amazing Thing About Trees
by Veritasium
689,200 views
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. -
3
What's In A Candle Flame?
by Veritasium
971,472 views
Microwave grape plasma: http://www.youtube.com/watch?v=RwTjsRt0Fzo
Northern Lights: http://www.youtube.com/watch?v=knwiWm4DpvQ
Nanodiamonds in candle flames: http://www.youtube.com/watch?v=KzOkuGQC3Rw
Relight Candle Trick: http://www.youtube.com/watch?v=1tXPVTIisl0
Is a flame really a plasma? Well it depends on your definition of plasma, but there are certainly ions in a flame, formed as molecules collide with each other at high speed, sometimes knocking electrons off of their atoms.
Special thanks to the Palais de la Decouverte for helping me perform this experiment. Using tens of thousands of volts on two metal plates, we created a strong electric field around the plasma. This pulled positive ions in one direction and negative ions in the other direction elongating the flame horizontally and causing it to flicker like a "papillon" (butterfly). Then we showed that much longer sparks can be made through the flame than through air since the ions increase the conductivity. -
4
Jetpack Rocket Science
by Veritasium
1,125,128 views
Check out 2Veritasium! http://dft.ba/-ve2
MinutePhysics has a great video on Milkman, vomiting levitator: http://dft.ba/-vomphysics
Jetpacking was awesome fun! Despite the fat lip I had a great time. I think knowing a bit about physics actually helps fly the jetpack. It works on the same principle as a rocket (Newton's 3rd law) but unlike the shuttle, you don't carry your own propellant with you. Instead, water is pumped out of the lake by the jetski at up to 60 litres a second. It is then fired out of the nozzles at around 15 m/s creating 1800 N of force, the equivalent of about 150 fire extinguishers. On me this can produce acceleration of about 1.5g's.
Music by Kevin McLeod (http://incompetech.com) Silly Fun, Also Sprach Zarathustra
Supported by Science Alert: http://on.fb.me/14ehuxA
Slow motion filming by Questacon: http://bit.ly/ZoWFGR -
5
Levitating Barbecue! Electromagnetic Induction
by Veritasium
748,538 views
At the Palais de la Decouverte in Paris, they showed me this experiment where a 1kg aluminium plate is levitated above a large coil of wire that is being supplied with 800A of alternating current at 900Hz. This is by far the best demonstration of electromagnetic induction I have ever seen.
Back in London, I visited the magnetic lab of Michael Faraday in the basement of the Royal Institution. It was here that he did his groundbreaking work on induction. People had previously observed that current in a wire causes a compass needle to deflect, but more exciting was the prospect of using a magnetic field to generate current. Faraday created his famous induction ring by winding two coils of insulated wire onto an iron ring. When he connected a battery to one coil, a small pulse of current was induced in the other. When the battery was disconnected, current was induced in the other direction. This led Faraday to the conclusion that current was induced in the second coil only when the magnetic field through it was changing.
And if they hadn't been wrapped on the same ring, Faraday may have noticed that the two coils repel each other when the current is induced due to the interaction of their magnetic fields. This is the same thing that is happening with the aluminium plate, except we're using alternating current to create a continually changing magnetic field. This induces an alternating current in the plate, producing an opposing magnetic field which levitates the disk. -
6
How Does a Transistor Work?
by Veritasium
466,531 views
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Supported by TechNYou: http://bit.ly/19bBX5G
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How does a transistor work? Our lives depend on this device. When I mentioned to people that I was doing a video on transistors, they would say "as in a transistor radio?" Yes! That's exactly what I mean, but it goes so much deeper than that. After the transistor was invented in 1947 one of the first available consumer technologies it was applied to was radios, so they could be made portable and higher quality. Hence the line in 'Brown-eyed Girl' - "going down to the old mine with a transistor radio."
But more important to our lives today, the transistor made possible the microcomputer revolution, and hence the Internet, and also TVs, mobile phones, fancy washing machines, dishwashers, calculators, satellites, projectors etc. etc. A transistor is based on semiconductor material, usually silicon, which is 'doped' with impurities to carefully change its electrical properties. These n and p-type semiconductors are then put together in different configurations to achieve a desired electrical result. And in the case of the transistor, this is to make a tiny electrical switch. These switches are then connected together to perform computations, store information, and basically make everything electrical work intelligently.
Special thanks to PhD Comics for awesome animations: http://bit.ly/16ZXcVY
And thanks to Henry Reich and Vanessa Hill for reviews of earlier drafts of this video.
Music: Kevin MacLeod (incompetech.com) Decisions -
7
The Original Double Slit Experiment
by Veritasium
491,538 views
Light is so common that we rarely think about what it really is. But just over two hundred years ago, a groundbreaking experiment answered the question that had occupied physicists for centuries. Is light made up of waves or particles?
The experiment was conducted by Thomas Young and is known as Young's Double Slit Experiment. This famous experiment is actually a simplification of a series of experiments on light conducted by Young. In a completely darkened room, Young allowed a thin beam of sunlight to pass through an aperture on his window and onto two narrow, closely spaced openings (the double slit). This sunlight then cast a shadow onto the wall behind the apparatus. Young found that the light diffracted as it passed through the slits, and then interfered with itself, created a series of light and dark spots. Since the sunlight consists of all colours of the rainbow, these colours were also visible in the projected spots. Young concluded that light consist of waves and not particles since only waves were known to diffract and interfere in exactly the manner that light did in his experiment.
The way I have always seen this experiment performed is with a laser and a manufactured double slit but since the experiment was conducted in 1801 I have always thought that it should be possible to recreate the experiment using sunlight and household materials. That is basically what I did here. I will show the interference pattern I observed with my homemade double slit on 2Veritasium but I chose to use a manufactured double slit here to ensure that the pattern was impressive for observers at the beach.
Special thanks to Henry, Brady, and Rupert for their cameos, Glen for filming and Josh for helping create the apparatus. Thanks also to the Royal Society for allowing us to view the original manuscript of Young's lecture and the University of Sydney for lending the double slits.
Music by Kevin Mcleod (incompetech.com) Danse Macabre, Scissors -
8
Spinning Tube Trick
by Veritasium
722,465 views
To see what this looks like from under a glass table, see http://www.youtube.com/watch?v=E9WUaBGH7_I
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9
Awesome HD Slinky Slow-Mo
by Veritasium
1,498,416 views
Read a pre-print of the physics paper here: http://arxiv.org/abs/1208.4629
Music by Kevin McLeod http://incompetech.com
Songs: Industrial Music Box, Heavy Interlude, Pale Rider, Decisions.
Slow motion photography courtesy of Questacon http://questacon.edu.au
The original goal of Veritasium was to show the beauty of science and I think the first minute and a half of this is the closest I've come. This is the last in a series of six videos about slinkies. -
10
Why Do You Make People Look Stupid?
by Veritasium
402,495 views
Raw interviews: http://www.youtube.com/watch?v=8dcw98B2Nzg
The question has arisen often enough that I thought I'd answer it. If you hold views that are consistent with the majority of the population, does that make you stupid? I don't think so. Science has uncovered a lot of counterintuitive things about the universe, so it's unsurprising that non-scientists hold beliefs inconsistent with science. But when we teach, we must take into account what the learners know, including their incorrect knowledge. That is the reason a lot of Veritasium videos start with the misconceptions.
Want to read my PhD? You can download the full text here: http://www.physics.usyd.edu.au/pdfs/research/super/PhD(Muller).pdf -
11
Where Do Trees Get Their Mass From?
by Veritasium
299,043 views
Complete unedited interviews: http://www.youtube.com/watch?v=8dcw98B2Nzg
Trees can weigh hundreds or even thousands of tons, but where do they get this mass from? A few common answers are: the soil, water, and sunlight. But the truth is the vast majority of a dry tree's mass comes from the air - it originated as carbon dioxide -
12
Misconceptions About Temperature
by Veritasium
546,243 views
Made for ABC TV Catalyst http://www.abc.net.au/catalyst/ as an extended version of my Comparing Temperatures video: http://www.youtube.com/watch?v=hNGJ0WHXMyE
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13
World's Longest Vertical Straw
by Veritasium
735,654 views
What is the longest drinking straw that you can actually drink out of? Well in this video, we put the theory to the test. We started off with a one metre long straw made out of drinking straws taped together. We moved on to two pieces of plastic tubing, each 6 metres in length with different diameters. Then we tried a 10.5 metre tube over a cliff's edge. The maximum we achieved was about 7 metres though theoretically up to 10.3 metres is possible if a perfect vacuum is created.
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14
How Does A Wing Actually Work?
by Veritasium
268,043 views
Lift is an important concept, not only in flying but also in sailing. This week I'm talking to Olympic Sailor, Hunter Lowden. But before I get to the physics of sailing I thought I would explain lift since it's generally poorly understood.
minutephysics http://bit.ly/Muh6CC
1veritasium http://bit.ly/MrupzL
efit30 http://bit.ly/O4CMme
appchat http://bit.ly/NxAMlX
erikaanear http://bit.ly/MdyUzQ
whoisjimmy http://bit.ly/LtFzpW
numberphile http://bit.ly/numberphile
Music by Nathaniel Schroeder
youtube: http://bit.ly/pakJLE
myspace: http://mysp.ac/qtmZQj -
15
Making SOLID Nitrogen!
by Veritasium
862,040 views
What happens when you decrease the pressure around a liquid? It boils. Water boils at room temperature once the pressure is low enough. What is interesting is that this decreases the temperature of the liquid. The fastest molecules escape, leaving the slower ones behind.
Using this trick with liquid nitrogen, it is possible to create solid nitrogen at a temperature of -210C. We then poured the solid and liquid nitrogen mixture onto a tray of water. The surface of the water became so cold that CO2 solidified out of the atmosphere on its surface. Then, since CO2 does not pass through the liquid phase at atmospheric pressure, it was propelled on the water surface by jets of gas as it sublimed.
Huge thanks to the Palais de la Decouverte.
Music by Kevin MacLeod of Incompetech.com (Mirage) -
16
How To Make Graphene
by Veritasium
284,132 views
My entry to the techNyou Science Ambassadors competition, visit www.facebook.com/talkingtechnology and www.youtube.com/technyouvids to find out more about these guys.
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17
Atomic Bonding Song
by Veritasium
215,736 views
Starring: Christie Wykes as Chlorine, Carbon, and Sodium
Director of Photography: Sean McCallum
Gravity (John Mayer Cover) http://www.youtube.com/watch?v=u7KpH9_I2Dw
I'm Atoms (Jason Mraz Cover) http://www.youtube.com/watch?v=DBjZz0iQrzI
Electricity (Jet Cover) http://www.youtube.com/watch?v=cY-kiddvAg0
Experiments A Cappella http://www.youtube.com/watch?v=lRbI_vPyOnc -
18
How Far Away is the Moon? (The Scale of the Universe)
by Veritasium
760,344 views
If the Earth were the size of a basketball and the moon a tennis ball, how far apart would they be? Diagrams that are not to scale make us think that they're closer than they really are.
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19
Are You Lightest In The Morning?
by Veritasium
319,041 views
Are you heaviest at night before you go to bed and lightest in the morning? I tried to tease out the factors to figure out what really causes weight gain and loss during the day, and what causes daily weight fluctuations.
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20
Shadow Illusion
by Veritasium
240,228 views
When sunlight shines through a small hole, it casts a circular image on the wall regardless of the shape of the hole. The size of the hole also doesn't affect the size of the image.
This counterintuitive demonstration shows that the hole is acting like a pinhole camera, producing an image of the sun on the wall. Therefore the size and shape of the hole have no effect on the size and shape of the image. -
21
Impress Her With Nanodiamonds
by Veritasium
337,261 views
Scientists have recently discovered nanodiamonds in the flames of ordinary candles. They are produced at a rate of about 1.5 million per second. Unfortunately they are also burned up at this rate and released into the atmosphere as carbon dioxide. Still this finding may prove useful in the ongoing search for economical ways to produce diamonds.
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22
Make Plasma With Grapes In The Microwave!
by Veritasium
402,417 views
When a grape is cut nearly in half and placed in a microwave, plasma is produced. Please use caution if attempting this experiment: don't leave the microwave on for too long, make sure the area is well ventilated, and stand back. Remember the contents will be very hot afterwards.
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23
Chain Drop Experiment
by Veritasium
273,972 views
On a mobile device? Click here: http://www.youtube.com/watch?v=X-QFAB0gEtE for the answer
Two 1.5kg masses are released simultaneously from the top of a 10m high wall. One is attached to a chain while the other is free. Which one will hit the ground first? -
24
Physics Nobel Prize 2011 - Brian Schmidt
by Veritasium
75,344 views
The Nobel Prize for physics in 2011 was awarded to Brian Schmidt, Adam Riess, and Saul Perlmutter for discovering that the universe is expanding at an accelerating rate. This finding was completely unexpected because it was thought that gravity should slow the expansion of the cosmos. The best current explanation of why the universe is accelerating is that there is some energy tied to empty space which pushes matter apart. This 'Dark Energy' makes up 73% of the universe but is very difficult to detect. Images courtesy of NASA/NASAimages.org and Maritza A. Lara-Lopez
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25
How Special Relativity Makes Magnets Work
by Veritasium
419,198 views
MinutePhysics on permanent magnets: http://www.youtube.com/watch?v=hFAOXdXZ5TM
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Magnetism seems like a pretty magical phenomenon. Rocks that attract or repel each other at a distance - that's really cool - and electric current in a wire interacts in the same way. What's even more amazing is how it works. We normally think of special relativity as having little bearing on our lives because everything happens at such low speeds that relativistic effects are negligible. But when you consider the large number of charges in a wire and the strength of the electric interaction, you can see that electromagnets function thanks to the special relativistic effect of length contraction. In a frame of reference moving with the charges, there is an electric field that creates a force on the charges. But in the lab frame, there is no electric field so it must be a magnetic field creating the force. Hence we see that a magnetic field is what an electric field becomes when an electrically charged object starts moving.
I was inspired to make this video by Prof. Eric Mazur http://mazur.harvard.edu/emdetails.php
Huge thank you to Ralph at the School of Physics, University of Sydney for helping us out with all this magnetic gear. Thanks also to geology for loaning the rocks.
This video was filmed in the studio at the University of New South Wales - thanks to all the staff there for their time and support.
Music: Firefly in a Fairytale, Nathaniel Schroeder, and Love Lost (Instrumental) by Temper Trap licensed from CueSongs.com -
26
10 Facts About Great White Sharks
by Veritasium
1,816,696 views
Remarkably little is known about great white sharks, but they are similar to humans in a lot of ways - they give birth to live young, maintain a higher body temperature than their surroundings and they are apex predators. There are also many misconceptions about these sharks: people think they don't get cancer and that they reside mainly in shallow waters near beaches. In this video I summarize some of the most interesting things I learned about sharks on my cage diving adventure.
Special thanks to Rodney Fox Shark Expeditions for making this trip possible: http://bit.ly/rodneyfox
Thanks also to Tourism South Australia for facilitating the trip: http://bit.ly/1aq9MgV
Chris Cassella or C² as he is known after this trip was a shark spotter extraordinaire. He also took some of the best shark footage in this video. It was his idea to go on this expedition, which was definitely a once in a lifetime experience, so I am in his debt. Chris, I look forward to going on more great adventures with you. Check out Chris's facebook page ScienceAlert http://on.fb.me/18nhyLp
