WEBVTT FILE 1 00:00:00.010 --> 00:00:11.110 Music 2 00:00:11.130 --> 00:00:15.150 Narrator: This demonstration explores what happens inside a large 3 00:00:15.170 --> 00:00:19.200 star when fusion stops at the end of its life. You're going to need 4 00:00:19.220 --> 00:00:23.230 an empty aluminum soda can, a hot 5 00:00:23.250 --> 00:00:27.290 plate, some water, 6 00:00:27.310 --> 00:00:31.330 something to measure the water with, like a tablespoon, 7 00:00:31.350 --> 00:00:35.390 a bowl of ice water, and a pair of tongs 8 00:00:35.410 --> 00:00:39.440 to flip the can over. First, place a small amount of water inside the aluminum 9 00:00:39.460 --> 00:00:43.510 soda can, about a tablespoon or two. Set the can on the 10 00:00:43.530 --> 00:00:47.540 hot plate, and heat until the water starts to boil. Listen for the sound 11 00:00:47.560 --> 00:00:51.560 of the water boiling and look for steam coming out of the top. When plenty of 12 00:00:51.580 --> 00:00:55.600 steam is coming out of the top of the soda can, quickly pick it up with the tongs and 13 00:00:55.620 --> 00:00:59.620 flip it over, open side down, into the bowl of ice water. It helps to use 14 00:00:59.640 --> 00:01:03.660 an underhand motion, so you can easily flip your wrist over and dunk the can. 15 00:01:03.680 --> 00:01:07.680 The can will implode, just like the core of a large star. 16 00:01:07.700 --> 00:01:11.690 This activity is all about balance, or equilibrium. When you 17 00:01:11.710 --> 00:01:15.710 have an empty soda can, the air pressure on the inside and the air pressure outside 18 00:01:15.730 --> 00:01:19.740 are in equilibrium. When the water boils and you have steam, 19 00:01:19.760 --> 00:01:23.810 the steam on the inside is still in equilibrium with the air pressure on the outside. 20 00:01:23.830 --> 00:01:27.830 But once that steam turns into liquid water, that equilibrium is broken and the can 21 00:01:27.850 --> 00:01:31.850 collapses. Similarly, in a star, you have a balance between 22 00:01:31.870 --> 00:01:35.910 the energy from fusion pushing outwards, and gravity holding the star together for the 23 00:01:35.930 --> 00:01:39.980 majority of the star's life. But when fusion stops, all of a sudden that 24 00:01:40.000 --> 00:01:44.030 equilibrium is broken and the star collapses, just like the can. 25 00:01:44.050 --> 00:01:55.829 Music