Full transcript
0:01Water.
0:02You might not see it, but this is...
0:07Here's why.
0:08Every molecule of water on the Earth
0:10and inside you or any other living thing
0:13has existed for billions of years.
0:16After it came to Earth, that water has been cycling
0:18through rocks, air, animals, plants and back again.
0:22Each molecule has been on an incredible voyage
0:24before coming to you.
0:26At some point, the water inside you would have been inside dinosaurs,
0:29bacteria, the oceans, storm clouds, the polar ice caps and much more.
0:35All of the water on Earth is alien.
0:38They might be a familiar part of our world,
0:40but our oceans formed hundreds of millions of years
0:43after our planet took shape.
0:45The water arrived on asteroids and comets from space,
0:48objects from the edge of our solar system.
0:50They were leftovers of the vast clouds of dust and rocks
0:54that didn't quite make it into planets.
0:56This is the origin of all the water you can see on the Earth.
1:01Water doesn't follow the normal rules of chemistry.
1:04For a start, it shouldn't really be a liquid on our planet.
1:07A water molecule is made from two very light atoms,
1:10hydrogen and oxygen.
1:12And at the temperatures and pressures on the surface of the Earth,
1:15rules of chemistry say that water should be a gas.
1:17And, unlike any other chemical, when water freezes it expands.
1:22And so ice floats on water.
1:25Now you see this every day,
1:26but take a moment to think about how weird that is.
1:29Over time, this odd behaviour has been very useful.
1:33By insulating the water underneath,
1:35floating ice has enabled complex life to survive and evolve on our planet,
1:40despite the many ice ages that have frozen the Earth's surface solid.
1:45And the strangeness just goes on and on.
1:48Did you know that hot water freezes faster than cold?
1:52Yes, really.
1:53No-one knows why.
1:55Water molecules can float upwards, against the force of gravity.
1:58That's because they love to stick to each other.
2:00They're so good at it
2:02that they can actually pull each other up through tiny channels,
2:05such as the tiny blood vessels in your body.
2:07That's how oxygen and nutrients reach the edges of your brain.
2:11The same process, called capillary action,
2:14allows plants to move water from deep below the ground
2:17to nourish the leaves and branches that grow in the sunshine.
2:20Our solar system is drowning in water.
2:24Once upon a time,
2:25we thought that we were alone on Earth with so much water,
2:28but in fact it's the second most common molecule in the universe.
2:31We now know there's water on the moon, on Mars, Pluto.
2:35In fact there's H2O on almost every object in our solar system.
2:39And where there's water, there could be life.
2:43So pour yourself a glass of water now,
2:45and take a good look at this colourless, featureless
2:48and tasteless material.
2:50It's actually remarkable.
2:53It breaks so many rules of chemistry
2:55that scientists struggle to understand it.
2:58But without its rebel behaviour,
2:59none of us, nor our world, would exist.
3:02You're only here watching this video because water is so strange.
3:08Thanks for watching. Don’t forget to subscribe! :)