1
00:00:00,040 --> 00:00:02,840
Speaker 1: Hey, everybody, if you're listening to this podcast, I expect

2
00:00:02,960 --> 00:00:06,680
Speaker 1: that you crave and enjoy knowledge, right, So that's why

3
00:00:06,720 --> 00:00:09,080
Speaker 1: I want to tell you about the new the Great

4
00:00:09,119 --> 00:00:12,639
Speaker 1: Courses Plus video learning service. This is a service where

5
00:00:12,680 --> 00:00:16,080
Speaker 1: you can learn about anything that interests you, with unlimited

6
00:00:16,120 --> 00:00:21,040
Speaker 1: access to over seven thousand video lectures on fascinating topics,

7
00:00:21,040 --> 00:00:25,480
Speaker 1: including science, history, even how to cook. All of this

8
00:00:25,640 --> 00:00:28,639
Speaker 1: is taught by top professors and I really want you

9
00:00:28,680 --> 00:00:31,400
Speaker 1: to try it out, so they're giving brain stuff listeners

10
00:00:31,440 --> 00:00:35,320
Speaker 1: a special chance to watch hundreds of their courses for free.

11
00:00:35,560 --> 00:00:39,760
Speaker 1: This includes the course that I just watched called Fundamentals

12
00:00:39,760 --> 00:00:43,440
Speaker 1: of Photography Now. This is taught by professional photographer and

13
00:00:43,560 --> 00:00:48,360
Speaker 1: National Geographic Fellow Joel Sartore, and he gives you techniques

14
00:00:48,400 --> 00:00:54,120
Speaker 1: to take better pictures. He has valuable advice on lighting, framing, perspectives,

15
00:00:54,280 --> 00:00:56,480
Speaker 1: all of it. You should totally check it out. I'm

16
00:00:56,480 --> 00:00:58,960
Speaker 1: a big fan of The Great Courses Plus and I

17
00:00:59,000 --> 00:01:01,560
Speaker 1: want you to try it out too, so we made

18
00:01:01,560 --> 00:01:04,280
Speaker 1: a deal with them and brain Stuff Listeners. When you

19
00:01:04,319 --> 00:01:07,200
Speaker 1: sign up, you will immediately get a free month of

20
00:01:07,400 --> 00:01:11,440
Speaker 1: unlimited access to all of their lectures. Start your free

21
00:01:11,440 --> 00:01:14,880
Speaker 1: trial today by going to the Great Courses plus dot

22
00:01:14,920 --> 00:01:19,360
Speaker 1: com slash brain Stuff. That's the Great Courses plus dot

23
00:01:19,400 --> 00:01:25,160
Speaker 1: com slash brain Stuff. Welcome to brain Stuff from how

24
00:01:25,200 --> 00:01:33,319
Speaker 1: Stuff Works. Hey, brain Stuff, I'm Christian Sager. The official

25
00:01:33,440 --> 00:01:37,039
Speaker 1: Marvel Comics database says that Captain America's shield is a

26
00:01:37,080 --> 00:01:40,880
Speaker 1: metal disc that's approximately two point five feet in diameter

27
00:01:41,200 --> 00:01:45,119
Speaker 1: and weighs twelve pounds, But Rheta. Laine at Wired Magazine

28
00:01:45,120 --> 00:01:47,240
Speaker 1: did some math and figured out that it would be

29
00:01:47,280 --> 00:01:52,000
Speaker 1: more likely to weigh forty three point nine pounds, despite

30
00:01:52,000 --> 00:01:55,560
Speaker 1: the shield being made of a unique alloy combining vibranium,

31
00:01:55,560 --> 00:01:59,960
Speaker 1: which is a fictional metal steal, and an unknown third component.

32
00:02:00,480 --> 00:02:03,120
Speaker 1: Elaine also figured out that the density of the shield

33
00:02:03,360 --> 00:02:06,640
Speaker 1: would be somewhere between eight thousand, seven hundred and sixty

34
00:02:06,680 --> 00:02:11,680
Speaker 1: seven and four thousand, three eighty three kilgrams per meter cubed.

35
00:02:12,320 --> 00:02:17,040
Speaker 1: That is, somewhere between the density of iron and titanium. Now.

36
00:02:17,040 --> 00:02:19,440
Speaker 1: In the Captain America comics, the story goes that Dr

37
00:02:19,520 --> 00:02:23,919
Speaker 1: Myron McLean was attempting to replicate hercules golden mace by

38
00:02:23,919 --> 00:02:28,280
Speaker 1: fusing vibranium with an experimental iron alloy. Some say it

39
00:02:28,320 --> 00:02:31,000
Speaker 1: was a steel alloy, but even McClain didn't know what

40
00:02:31,080 --> 00:02:34,640
Speaker 1: it was because he fell asleep when an unknown catalyst

41
00:02:34,720 --> 00:02:37,640
Speaker 1: was introduced to the process. He was never able to

42
00:02:37,720 --> 00:02:41,080
Speaker 1: duplicate the process, so the government painted the disk and

43
00:02:41,120 --> 00:02:44,280
Speaker 1: gave it to Captain America. But how would you forge

44
00:02:44,320 --> 00:02:47,720
Speaker 1: such a thing, especially since metallurgy is so complicated. Just

45
00:02:47,800 --> 00:02:51,799
Speaker 1: the forging temperature alone depends on the materials carbon content,

46
00:02:52,120 --> 00:02:57,279
Speaker 1: it's alloy composition, maximum plasticity, and the amount of reduction required.

47
00:02:57,680 --> 00:03:00,560
Speaker 1: Was it heated by induction or by continue was fuel

48
00:03:00,600 --> 00:03:04,320
Speaker 1: fired furnaces With a material this unique, you would have

49
00:03:04,400 --> 00:03:09,000
Speaker 1: to carefully control the heating process. Now, forgibility is how

50
00:03:09,120 --> 00:03:14,480
Speaker 1: easy or difficult a material resists deformation, And since Captain

51
00:03:14,520 --> 00:03:17,560
Speaker 1: America's shield is indestructible, it would have to be a

52
00:03:17,760 --> 00:03:21,400
Speaker 1: very narrow forging temperature range, meaning it could only be

53
00:03:21,560 --> 00:03:26,120
Speaker 1: forged for a short time after heating. With metallurgical factors

54
00:03:26,120 --> 00:03:30,040
Speaker 1: like crystal structure, chemical composition, and grain size at play.

55
00:03:30,080 --> 00:03:33,920
Speaker 1: The only way McClain could have diminished their influence would

56
00:03:33,919 --> 00:03:39,000
Speaker 1: be by adding alloying elements, possibly compounds that easily dissolve

57
00:03:39,080 --> 00:03:41,760
Speaker 1: within the metal. There are all types of elements that

58
00:03:41,800 --> 00:03:44,840
Speaker 1: could have been introduced, but it's likely that Captain America's

59
00:03:44,880 --> 00:03:48,600
Speaker 1: shield was forged like a super alloy. This is how

60
00:03:48,720 --> 00:03:52,000
Speaker 1: metall aer just referred to iron based, nickel base and

61
00:03:52,120 --> 00:03:56,440
Speaker 1: cobalt based alloys, specifically the ones that offer very high

62
00:03:56,440 --> 00:04:00,560
Speaker 1: strength at high temperatures. These really high string metals and

63
00:04:00,600 --> 00:04:04,040
Speaker 1: iron based grades are the least difficult ones to work with,

64
00:04:04,520 --> 00:04:07,920
Speaker 1: so that would narrow down McClain's experimental alloy to iron.

65
00:04:08,640 --> 00:04:11,320
Speaker 1: Super alloys are really difficult to forge because of their

66
00:04:11,400 --> 00:04:15,520
Speaker 1: narrow temperature range. You can't even use regular sizing presses

67
00:04:15,520 --> 00:04:19,040
Speaker 1: and hammers on them because they'll deform. They even wear

68
00:04:19,120 --> 00:04:23,200
Speaker 1: down the tools designed for forging them pretty easily. They're

69
00:04:23,240 --> 00:04:28,040
Speaker 1: also extremely expensive, like ten times the price of carbon steel.

70
00:04:28,560 --> 00:04:31,680
Speaker 1: Sounds a lot like Captain America's shield, right, But how

71
00:04:31,720 --> 00:04:34,800
Speaker 1: do we explain the shield's ability to absorb kinetic energy

72
00:04:34,880 --> 00:04:38,920
Speaker 1: supposedly from the vibranium in the alloy. Usually materials absorb

73
00:04:39,000 --> 00:04:43,520
Speaker 1: kinetic energy through other mechanisms like plastic or elastic deformation

74
00:04:44,080 --> 00:04:48,000
Speaker 1: or dynamic fluid flow, But cap shield doesn't seem to

75
00:04:48,080 --> 00:04:52,200
Speaker 1: be an elastometric material, and it's not organic like polyurethane

76
00:04:52,760 --> 00:04:56,560
Speaker 1: in the movies. It actually seems to reflect vibration rather

77
00:04:56,640 --> 00:04:59,599
Speaker 1: than absorb it, like when Thor hits it with Mjolner

78
00:04:59,680 --> 00:05:02,839
Speaker 1: in that first Avengers movie and the shock wave flattens

79
00:05:02,839 --> 00:05:06,760
Speaker 1: a whole forest. Perhaps that was because the shield reached

80
00:05:06,760 --> 00:05:10,160
Speaker 1: its absorption limit. Another thing that's tough to explain is

81
00:05:10,200 --> 00:05:13,799
Speaker 1: how aerodynamic the shield is. If it really weighed forty

82
00:05:13,839 --> 00:05:16,880
Speaker 1: three point nine pounds, it would be difficult to throw,

83
00:05:17,000 --> 00:05:20,680
Speaker 1: even for a guy in peak physical condition like Steve Rogers.

84
00:05:21,080 --> 00:05:24,680
Speaker 1: In the comics, Tony Stark actually puts electro magnets under

85
00:05:24,720 --> 00:05:28,320
Speaker 1: the shield to help control it in midflight, but Captain

86
00:05:28,360 --> 00:05:32,680
Speaker 1: America later ditched them because they upset the shields natural balance.

87
00:05:33,240 --> 00:05:36,240
Speaker 1: It seems like the soldier and the shield are made

88
00:05:36,279 --> 00:05:44,160
Speaker 1: for each other. Check out the brain stuff channel on YouTube,

89
00:05:44,240 --> 00:05:46,400
Speaker 1: and for more on this and thousands of other topics,

90
00:05:46,560 --> 00:06:02,000
Speaker 1: visit how stuff works dot com.