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Music

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Narrator: This demonstration explores what happens inside a large

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star when fusion stops at the end of its life. You're going to need

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an empty aluminum soda can, a hot

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plate, some water,

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something to measure the water with, like a tablespoon,

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a bowl of ice water, and a pair of tongs

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to flip the can over. First, place a small amount of water inside the aluminum

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soda can, about a tablespoon or two. Set the can on the

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hot plate, and heat until the water starts to boil. Listen for the sound

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of the water boiling and look for steam coming out of the top. When plenty of

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steam is coming out of the top of the soda can, quickly pick it up with the tongs and

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flip it over, open side down, into the bowl of ice water. It helps to use

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an underhand motion, so you can easily flip your wrist over and dunk the can.

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The can will implode, just like the core of a large star.

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This activity is all about balance, or equilibrium. When you

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have an empty soda can, the air pressure on the inside and the air pressure outside

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are in equilibrium. When the water boils and you have steam,

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the steam on the inside is still in equilibrium with the air pressure on the outside.

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But once that steam turns into liquid water, that equilibrium is broken and the can

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collapses. Similarly, in a star, you have a balance between

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the energy from fusion pushing outwards, and gravity holding the star together for the

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majority of the star's life. But when fusion stops, all of a sudden that

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equilibrium is broken and the star collapses, just like the can.

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Music