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Veritasium
Misconceptions
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1
Why Do Venomous Animals Live In Warm Climates?
by Veritasium
787,288 views
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As a Canadian-Australian, I have always wondered why it is that Australia has so many venomous animals that can kill you while Canada has virtually none. But it's not just Australia - it seems like all beautiful, warm places are cursed with venomous native species. So I set out to find the truth: why have all these venomous species evolved in the world's best holiday destinations?
I asked chemists, visited the zoo, interviewed entomologists and snake experts. The answer I found was complicated:
1. The majority of venomous species are ectotherms, cold-blooded creatures whose internal temperatures are governed by their surroundings.
2. This means they have limited periods of activity - mainly while it's warm out, and can only exert short bursts of energy, so they are generally "sit and wait" predators. This may explain why they, more than mammals or birds, evolved venom.
3. It also explains why there are more of these species in warm climates. There are more of all species in warm climates, but this trend is especially pronounced for ectotherms.
4. So there are a greater number of venomous species in warm places, simply because there are more species in warm places. Cold climates still have venomous creatures, like the rattlesnakes of Canada and European vipers.
5. But history also has a role to play. In Australia, there were no snakes until 20 million years ago when a venomous sea snake from Asia encountered the land, sending venomous species to all corners of the continent. Later non-venomous arrivals have done well in the tropics but not as well in Australia's colder climates, so venomous types still dominate there. Hawaii has no venomous land snakes and nor does Jamaica.
6. The recent ice age also would have driven ectotherms from the northern parts of the Northern Hemisphere. This is why there are no snakes in Ireland, for example.
Special thanks to Prof. Rick Shine, Prof. Dieter Hochuli, Prof. Roger Lowe, Prof. Martyn Poliakoff and Taronga Zoo, especially Joe Haddock and Dean Purcell.
Cinematography by Charles Clement -
2
Misconceptions About Temperature
by Veritasium
546,255 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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3
Where Do Trees Get Their Mass From?
by Veritasium
299,047 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 -
4
Where Does The Sun Get Its Energy?
by Veritasium
284,426 views
The sun has been producing light for about five billion years but where does all its energy come from? The most common idea is that the sun is burning gas - like a giant fireball in the sky. If this were true, the sun would have gone out long ago. So how is the sun actually fuelling itself? It is converting its own mass into energy. By combining protons (the nucleus of hydrogen) into helium, it squeezes some mass into energy - 4.3 billion kg per second. It is Einstein's famous E=mc^2 which gives us the quantitative relationship between mass and energy, where c is the speed of light.
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5
Are You Lightest In The Morning?
by Veritasium
319,043 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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6
Why Are Astronauts Weightless?
by Veritasium
159,531 views
http://www.abc.net.au/catalyst/team/default.htm
I have been working with Catalyst on ABC1 to bring some Veritasium to Australian TV. In this segment I ask why astronauts in the space station are weightless. The most common answer is because there is no gravity in space. But of course there is gravity in space, especially where the space station is located (only about 400km from Earth's surface). So astronauts still experience a gravitational pull - it's just that they and the space station are in free fall so they are accelerating together towards the Earth. The space station doesn't crash into the Earth because of its orbital velocity - it's going 28,000 km/h so as it falls, the Earth curves away from it. -
7
Shadow Illusion
by Veritasium
240,233 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. -
8
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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9
How Old Is The Earth?
by Veritasium
123,541 views
The Earth is clearly old, but exactly how old was difficult to work out. People long believed the Earth had only existed for several thousand years. Then, in the 1800's, a study of geological features (including fjords) led scientists to the conclusion that the planet must be much older - at least millions of years old. Later, the discovery of radioactivity provided a mechanism by which the Earth's core could be continually heated. This meant it was much older than previous estimates of 20-40 million years based on the cooling rate of the Earth. Today through many different methods we have established that the Earth is roughly 4.54 billion years old!
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10
Where Did The Earth Come From?
by Veritasium
137,198 views
Do we take the Earth for granted? It gives us life and sustains us in the manner we're accustomed to, but we don't know the first thing about it: like where did it come from? And how did it form? Most people recognize that the Earth has a big explosion in its history, which they refer to descriptively as the 'Big Bang.' But there are two very good reasons why the Big Bang is not directly responsible for forming the Earth: 1) It happened 13.7 billion years ago. That's more than 9 billion years before the Earth formed (what happened during that time?), and 2) After the Big Bang the universe consisted of only Hydrogen and Helium - not great raw material for building the Earth. The truth is the big bang formed stars, which exploded and then (perhaps) formed more stars, which exploded and then formed our solar system, including the Earth. The early stars performed the vital role of making the heavier elements of which Earth is composed and we are made.
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11
How long does it take for the earth to go around the sun?
by Veritasium
251,986 views
A recent survey of scientific literacy in Australia found 30% believe it takes one day for the Earth to go around the sun. This video provides qualitative evidence for the finding from Sydney's Eastern beaches.
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12
Why Does The Earth Spin?
by Veritasium
268,295 views
The Earth spins on its axis, completing a full revolution every day. By why does it do this? One of the most common misconceptions in physics is the belief that constant motion requires a constant force. So many people believe there must be some force in the Earth (e.g. gravity, centrifugal force) that keeps it spinning. In truth, no force is required because a fundamental property of mass is that it maintains its state of motion in the absence of external forces. This property is called inertia.
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13
How Does The Earth Spin?
by Veritasium
103,761 views
One of the most common physics misconceptions is that an unbalanced force causes constant motion. In truth, an unbalanced force leads to changes in motion - accelerations.
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14
States of Matter
by Veritasium
134,506 views
Everyone is familiar with liquid water, ice and water vapour, but what are the differences between these three states of matter? Solids, liquids and vapours of the same substance differ in the motion of the molecules and the distance between them.
Animations courtesy of VisChem (Trade Mark), Copyright 1995, Roy Tasker. Thanks for all your help! -
15
What Is Water Made Of?
by Veritasium
103,432 views
It's the most abundant liquid on the planet and by weight we are about 60% water. But do we know what it is made of?
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16
Why Is Ice Slippery?
by Veritasium
148,710 views
In Sydney, ice melts because it is warm out in the middle of the day (even in winter). This creates a layer of water on top that certainly makes it slippery. But should it be slippery at night or in a cold northern climate where the air temperature is below zero? Yes, because the pressure your skates apply to the ice actually lowers its melting point allowing you to glide along a thin layer of water.
Animation in this video is courtesy of VisChem (TM), Copyright 1995, Roy Tasker
For a more complete picture of the mechanisms involved in making ice slippery, check out this great article: http://lptms.u-psud.fr/membres/trizac/Ens/L3FIP/Ice.pdf -
17
What Is Chemistry?
by Veritasium
44,440 views
2011 is the international year of Chemistry. But what do Australians know about it?
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18
Radiation vs Radioactive Atoms
by Veritasium
160,762 views
There seems to be confusion about what radiation is and where it comes from. Many people believe it is the radiation that comes directly from nuclear power plants that poses a threat to public safety. In fact it is the radioactive atoms, which can escape in the event of an explosion, that pose a safety risk. They can be scattered by the wind over hundreds of kilometres. Then they may be ingested or breathed in. If they release radiation at this point, it is damaging to the body's molecules and cells because the radiation is delivered directly to tissues.
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19
Misconceptions About Heat
by Veritasium
79,703 views
When we touch something that is hot or cold, what are we actually sensing? Is it the temperature of the object, or the rate at which heat flows between the object and our hand?
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20
Can You Perceive Acceleration?
by Veritasium
115,296 views
How do our eyes scan across a landscape? Contrary to popular belief, they don't scan smoothly across a scene, they observe a series of images. The eye is capable of panning smoothly however. If something moves in your field of view, your eyes track it smoothly. This has an important effect on our perception of motion. It makes it more difficult to see when objects are accelerating since the eye tracks all motion quite smoothly.
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21
When Is A Bungee Jumper's Acceleration Max?
by Veritasium
53,207 views
When is the acceleration (rate of speeding up or slowing down) greatest during a bungy jump?
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22
Three Incorrect Laws of Motion
by Veritasium
224,349 views
Newton's Three Laws of Motion are a landmark achievement in physics. They describe how all objects move. Unfortunately most people do not really understand Newton's Laws because they have pre-existing ideas about the way the world works. This film is about those pre-existing ideas. By recognizing what people are thinking, it becomes easier to describe the correct scientific concepts of Newton's Three Laws and how they differ from this 'intuitive physics'.
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23
How Damaging is Radiation?
by Veritasium
214,887 views
What is radiation? Are all types harmful? What are the most common sources of damaging radiation? Most people view radiation as harmful and negative without understanding what makes it potentially damaging and which forms should be avoided. For example, many felt radiation from mobile phones probably caused cancer but few focused on the carcinogenic effects of UV rays.
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24
What Are Atoms and Isotopes?
by Veritasium
72,502 views
Most people recognize that atoms are the fundamental building blocks of all matter around us. An atom itself is composed of protons, neutrons and electrons. The simplest atom is the hydrogen atom because it consists of only one proton and one electron. If a neutron is added to the nucleus, the atom is still hydrogen, just a more massive version. Atoms of the same element (i.e. those with the same number of protons) but different numbers of neutrons are called isotopes.
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25
Khan Academy and the Effectiveness of Science Videos
by Veritasium
138,559 views
My PhD: http://www.physics.usyd.edu.au/super/theses/PhD(Muller).pdf
It is a common view that "if only someone could break this down and explain it clearly enough, more students would understand." Khan Academy is a great example of this approach with its clear, concise videos on science. However it is debatable whether they really work. Research has shown that these types of videos may be positively received by students. They feel like they are learning and become more confident in their answers, but tests reveal they haven't learned anything. The apparent reason for the discrepancy is misconceptions. Students have existing ideas about scientific phenomena before viewing a video. If the video presents scientific concepts in a clear, well illustrated way, students believe they are learning but they do not engage with the media on a deep enough level to realize that what was is presented differs from their prior knowledge. There is hope, however. Presenting students' common misconceptions in a video alongside the scientific concepts has been shown to increase learning by increasing the amount of mental effort students expend while watching it. -
26
What Is Gravity?
by Veritasium
69,778 views
People have a lot of different ideas about what gravity is: a downward force that stops you from flying off into space, an attraction smaller objects experience towards larger objects, or a mutual attraction between all masses. It is the last of these ideas that best reflects a scientific conception of gravity.
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27
What Forces Are Acting On You?
by Veritasium
64,030 views
What forces (i.e. pushes or pulls) are acting on you right now? Most people can identify the gravitational force down, but there must be something else otherwise you would accelerate down towards the center of the Earth. The other main force on you is called the normal force. It is a force perpendicular to the surface that supports you, like the ground or the seat of your chair. You compress this surface and it acts like a spring, pushing you up.
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28
Is There Gravity In Space?
by Veritasium
82,876 views
If you've seen footage from the International Space Station or any of the space shuttle missions, you know that astronauts float around as they orbit the Earth. Why is that? Is it because the gravitational force on them is zero in space? (Or nearly zero?) The truth is that the strength of the gravitational attraction is only slightly less than it is on Earth's surface. So how are they able to float? Well, they aren't floating - they're falling, along with the space station. They don't crash into the Earth because they have a huge orbital velocity. So as they accelerate towards the Earth, the Earth curves away beneath them and they never get any closer. Since the astronauts have the same acceleration as the space station, they feel weightless. It's like being in a free-falling elevator (without the disastrous landing).
Director of Photography: Stefan Smith
Camera Assistant: Raa Perajeev
Boom Operator: Maha Sivalingam
Production Coordinator: Adrian Tan
Production Assistants: James Peniata, Pratheep Ramachandran -
29
Which Hits The Ground First?
by Veritasium
53,828 views
A basketball and a 5kg medicine ball are dropped simultaneously. Which one hits the ground first? It seems obvious that the heavy one should accelerate at a greater rate and therefore land first because the force pulling it down is greater. But this is forgetting inertia - the tendency of mass to resist changes in motion. Therefore, although the force on the medicine ball is greater, it takes this larger force to accelerate the ball at the same rate as the basketball.
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30
Misconceptions About Falling Objects
by Veritasium
457,513 views
If you drop a heavy object and a light object simultaneously, which one will reach the ground first? A lot of people will say the heavy object, but what about those who know both will land at the same time? What do they think? Some believe both objects have the same gravitational pull on them and/or both fall to the ground with the same constant speed. Neither of these things is true, however. The force is greater on the heavy object and both objects accelerate at the same rate as they approach the earth, i.e. they both speed up but at the same rate.
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31
Best Film on Newton's Third Law. Ever.
by Veritasium
219,340 views
There is a gravitational force of attraction between the Earth and the moon, but is it mutual? That is, are the forces on the Earth and the moon equal? Most people would say no, the Earth exerts a greater force of attraction because it is larger and has more mass. This is a situation in which Newton's Third Law is relevant. Newton's Third Law says that for every force, there is an equal and opposite reaction force. So the force the Earth exerts on the moon must be exactly equal and opposite the force the moon exerts on the Earth. But how can that be - that the same size force keeps the moon orbiting, but barely affects the Earth? The answer is inertia - the tendency for all objects with mass to maintain their state of motion. Since the Earth has much more mass than the moon, it has greater inertia and therefore experiences much less acceleration for the same amount of force.
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32
Why Does the Moon Orbit Earth?
by Veritasium
51,472 views
It takes the moon about 27 days to orbit the Earth. What makes it go round? It is the gravitational attraction of the Earth on the moon. Due to the moon's velocity, the Earth keeps pulling the moon towards it without the moon actually getting closer to the Earth. This is similar to how satellites orbit the Earth.
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33
What causes the seasons?
by Veritasium
46,776 views
There are a few persistent misconceptions about what causes the seasons. Most believe it is the distance between the Earth and sun which varies to give us seasonal temperature variations. However it is actually the directness of the sun's rays leading to more intense sunshine in summer and less in winter.
