Bản chép lời đầy đủ của Breaking Bad Science: Can Teeth Really Explode Like Popcorn in a Fire?

WEBVTT 1 00:00:02.250 --> 00:00:04.950 In Breaking Bad, one of the officers made a passing 2 00:00:05.030 --> 00:00:09.519 comment about how teeth can explode like popcorn in a fire. 3 00:00:11.580 --> 00:00:13.419 So it was the fifth season of Breaking Bad where 4 00:00:13.439 --> 00:00:16.519 investigators examined the remains of Gus Fring's industrial laundry, which 5 00:00:16.559 --> 00:00:20.300 concealed one of the most sophisticated meth labs in television history. 6 00:00:20.460 --> 00:00:23.800 Following the destruction of the lab, investigators confront a familiar 7 00:00:23.899 --> 00:00:27.850 forensic problem. Extreme heat has damaged human remains, including the teeth, 8 00:00:28.850 --> 00:00:32.310 raising questions about whether the victim can be identified. The 9 00:00:32.350 --> 00:00:35.579 dialogue suggests that teeth exposed to tremendous heat, like I mentioned, 10 00:00:35.600 --> 00:00:41.659 can pop like popcorn. But is that scientifically possible? Well, surprisingly, 11 00:00:41.700 --> 00:00:45.079 there is some legitimate science behind the claim. Human teeth 12 00:00:45.140 --> 00:00:48.770 are durable structures. Their outer layer, enamel, consists of approximately 13 00:00:48.770 --> 00:00:53.750 96% mineral by weight, primarily a crystalline substance called hydroxyapatite. 14 00:00:54.729 --> 00:00:58.950 This makes enamel the hardest substance in the human body. However, 15 00:00:59.009 --> 00:01:01.189 hardness does not mean resistance to every form of damage. 16 00:01:01.350 --> 00:01:05.200 When teeth encounter extreme temperatures, several physical and chemical processes 17 00:01:05.260 --> 00:01:09.819 begin occurring. First, moisture within the tooth evaporates. As temperatures increase, 18 00:01:09.879 --> 00:01:14.299 organic components from the dentin begin decomposing. The enamel and 19 00:01:14.340 --> 00:01:18.260 dentin also respond differently to temperature changes. This creates internal 20 00:01:18.280 --> 00:01:23.189 stresses that can produce fractures, cracking, and fragmentation. Under sufficiently 21 00:01:23.250 --> 00:01:27.590 extreme conditions, teeth can break into multiple pieces. So the 22 00:01:27.629 --> 00:01:32.549 popcorn comparison sound is not entirely ridiculous. However, teeth don't 23 00:01:32.629 --> 00:01:35.250 normally explode in the same way that popcorn kernels do. 24 00:01:35.829 --> 00:01:40.250 Popcorn pops because water trapped inside a relatively impermeable shell 25 00:01:40.310 --> 00:01:44.159 turns into steam, building pressure onto the shell ruptures. Teeth 26 00:01:44.189 --> 00:01:51.900 undergo a more complicated process involving thermo-expansion, dehydration, chemical decomposition, 27 00:01:51.939 --> 00:01:56.189 and structural weakening. If teeth are destroyed by fire, does 28 00:01:56.230 --> 00:01:59.530 that prevent investigators from identifying a body? Well, not truly, 29 00:01:59.569 --> 00:02:04.519 not necessarily. Forensic ortodologists specialize in identifying human remains through 30 00:02:04.579 --> 00:02:10.759 dental structures. Even severely burned teeth may retain recognizable characteristics. Fillings, crowns, 31 00:02:10.960 --> 00:02:14.419 root structures, and other dental features can sometimes survive the temperatures. 32 00:02:15.460 --> 00:02:20.379 Investigators can compare these structures against dental records, including radiographs 33 00:02:20.460 --> 00:02:30.069 obtained before death. And dental evidence is only one identification method. So, 34 00:02:30.090 --> 00:02:32.689 a particularly interesting aspect of Breaking Bad is that the 35 00:02:32.729 --> 00:02:35.900 lab explosion would not necessarily create uniform temperatures throughout the 36 00:02:35.939 --> 00:02:40.900 building either. Fire behavior depends on oxygen availability, fuel distribution, ventilation, 37 00:02:40.919 --> 00:02:45.340 and the surrounding materials. Some objects may experience incredible heat, 38 00:02:45.379 --> 00:02:49.689 while others remain relatively protected. Investigators might recover useful evidence 39 00:02:49.710 --> 00:02:53.080 from certain areas that appear completely destroyed. And there's one 40 00:02:53.199 --> 00:02:57.800 final scientific complication. Even when investigators recover fragmented teeth, they 41 00:02:57.840 --> 00:03:02.379 may sometimes reconstruct dental structures or identify distinctive restorative materials. 42 00:03:03.090 --> 00:03:05.650 The destruction of a tooth does not automatically eliminate its 43 00:03:05.689 --> 00:03:10.330 forensic value. So was Breaking Bad scientifically accurate? Well, partially. 44 00:03:11.490 --> 00:03:15.129 Extreme heat can unquestionably destroy teeth, and severe thermal damage 45 00:03:15.169 --> 00:03:19.240 can make dental ID extremely difficult. But the suggestion that 46 00:03:19.280 --> 00:03:22.520 teas simply pop like popcorn and become completely useless, that 47 00:03:22.599 --> 00:03:24.159 oversimplifies the science.