How long is the coastline of Australia? One estimate is that it's about 12,500 km long. However the CIA world factbook puts the figure at more than double this, at over 25,700 km. How can there exist such different estimates for the same length of coastline? Well this is called the coastline paradox. Your estimate of how long the coastline is depends on the length of your measuring stick - the shorter the measuring stick the more detail you can capture and therefore the longer the coastline will be.

When pressure is applied to ice, its melting point is reduced so it turns to water. When the pressure is removed, however, it turns back into ice. This process is called 'regelation.' Big thanks to Art of Ice Sculptures www.icesculpture.com.au who donated the beautiful block of ice.

An atom is mostly empty space, but empty space is mostly not empty. The reason it looks empty is because electrons and photons don't interact with the stuff that is there, quark and gluon field fluctuations.
It actually takes energy to clear out space and make a true 'empty' vacuum. This seems incredibly counter-intuitive but we can make an analogy to a permanent magnet. When at low energies, like at room temperature, there is a magnetic field around the magnet due to the alignment of all the magnetic moments of the atoms. But if you add some energy to it by heating it, the particles gain thermal energy, which above the Curie temperature makes their magnetic moments randomly oriented and hence destroying the magnetic field. So in this case energy is needed to clear out the field, just as in the quantum vacuum.

Special thanks to Professor Derek Leinweber, find out more about his research here: http://bit.ly/ZZTKFP

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

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.

Heisenberg's uncertainty principle tells us that it is impossible to simultaneously measure the position and momentum of a particle with infinite precision. In our everyday lives we virtually never come up against this limit, hence why it seems peculiar. In this experiment a laser is shone through a narrow slit onto a screen. As the slit is made narrower, the spot on the screen also becomes narrower. But at a certain point, the spot starts becoming wider. This is because the photons of light have been so localised at the slit that their horizontal momentum must become less well defined in order to satisfy Heisenberg's uncertainty principle.

I based this video on one by Prof. Walter Lewin of MIT: http://bit.ly/100Wk2K

Henry (MinutePhysics) has previously made a video about Heisenberg's Uncertainty Principle where he treats it as less spooky and more a consequence of waves: http://bit.ly/TV3xO5

Sixty Symbols has a great video on Planck's constant: http://bit.ly/11upebY

Thanks to the University of Sydney for hosting this experiment, especially to Tom and Ralph for their assistance getting it working.

Music: Kevin McLeod (Incompetech.com) Mirage and Danse Macabre

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.

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Music by Nathaniel Schroeder
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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.

A quote by Einstein: A human being is a part of the whole, called by us "Universe", a part limited in time and space. He experiences himself, his thoughts and feelings as something separated from the rest — a kind of optical delusion of his consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty. Nobody is able to achieve this completely, but the striving for such achievement is in itself a part of the liberation and a foundation for inner security.

I bought 10,000 shade balls and tried to swim in them.

They appear to act like a non-Newtonian fluid: rigid under high shear stress, but they flow like a liquid under low shear.

A boomerang can execute its unique roundtrip flight by making use of three fundamental physics principles: lift, relative velocity, and gyroscopic precession.

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This short was made in support of #TeamWater

💧Support Team Water Here: https://www.TeamWater.org

The biggest YouTuber collab just happened on YouTube! Hundreds of creators got together to post a video about Team Water, a fundraiser launched by @MrBeast and @MarkRober to raise $40 million to give people all over the world clean drinking water!

Special thanks to Xi Shen and his team at The Hong Kong Polytechnic University for all their help. ACS Energy Lett. 2025, 10, 7, 3419–3429.

What is the optimal strategy for bowling? #science #veritasium #physics #bowling

LED's don't get their colour from their plastic covers. The blue LED was supposed to be impossible—until a young engineer proposed a moon-shot idea.

Now, it’s true that one of the benefits of flying at 30,000 ft is a smoother ride. This is high in the troposphere, the layer in which most weather occurs. So, there’s less turbulence and fewer storms to navigate around.

But this is not the main reason that planes fly so high.

All animals jump to about roughly the same height, but why is this? Aren't some animals bigger and stronger than others?

Planned obsolescence, explained. #veritasium #engineeering #lightbulbs

There is a riddle that is so counterintuitive, it still seems wrong even if you know the answer.

The 100 prisoners problem - comment your answer!

I took a boat through 96 million black plastic balls on the Los Angeles reservoir to find out why they're there.

The first time I heard about shade balls the claim was they reduce evaporation.

But it turns out this isn't the reason they were introduced.

I put cameras inside a dishwasher to wash away some common dishwasher myths. Learn more about the KitchenAid® 360° Max Jets Third Rack Dishwasher by visiting KitchenAid.com/veritasium #sponsored #kitchenaidambassador