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  • Water.

  • You might not see it, but this is probably the strangest thing in the universe.

  • Here's why.

  • Every molecule of water on the Earth and inside you or any other living thing has existed for billions of years.

  • After it came to Earth, that water has been cycling through rocks, air, animals, plants and back again.

  • Each molecule has been on an incredible voyage before coming to you.

  • At some point, the water inside you would have been inside dinosaurs, bacteria, the oceans, storm clouds, the polar ice caps and much more.

  • All of the water on Earth is alien.

  • They might be a familiar part of our world, but our oceans formed hundreds of millions of years after our planet took shape.

  • The water arrived on asteroids and comets from space, objects from the edge of our solar system.

  • They were leftovers of the vast clouds of dust and rocks that didn't quite make it into planets.

  • This is the origin of all the water you can see on the Earth.

  • Water doesn't follow the normal rules of chemistry.

  • For a start, it shouldn't really be a liquid on our planet.

  • A water molecule is made from two very light atoms, hydrogen and oxygen.

  • And at the temperatures and pressures on the surface of the Earth, rules of chemistry say that water should be a gas.

  • And, unlike any other chemical, when water freezes it expands.

  • And so ice floats on water.

  • Now you see this every day, but take a moment to think about how weird that is.

  • Over time, this odd behaviour has been very useful.

  • By insulating the water underneath, floating ice has enabled complex life to survive and evolve on our planet, despite the many ice ages that have frozen the Earth's surface solid.

  • And the strangeness just goes on and on.

  • Did you know that hot water freezes faster than cold?

  • Yes, really.

  • No one knows why.

  • Water molecules can float upwards, against the force of gravity.

  • That's because they love to stick to each other.

  • They're so good at it that they can actually pull each other up through tiny channels, such as the tiny blood vessels in your body.

  • That's how oxygen and nutrients reach the edges of your brain.

  • The same process, called capillary action, allows plants to move water from deep below the ground to nourish the leaves and branches that grow in the sunshine.

  • Our solar system is drowning in water.

  • Once upon a time, we thought that we were alone on Earth with so much water, but in fact it's the second most common molecule in the universe.

  • We now know there's water on the moon, on Mars, Pluto.

  • In fact there's H2O on almost every object in our solar system.

  • And where there's water, there could be life.

  • So pour yourself a glass of water now, and take a good look at this colourless, featureless and tasteless material.

  • It's actually remarkable.

  • It breaks so many rules of chemistry that scientists struggle to understand it.

  • But without its rebel behaviour, none of us, nor our world, would exist.

  • You're only here watching this video because water is so strange.


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B1 UK water earth molecule solar system solar chemistry

Why water is really, really weird | BBC Ideas

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    Seraya posted on 2020/06/02
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