WEBVTT - The Artifact: Glass Like Dough 0:00:03.279 --> 0:00:05.640 Welcome to Stuff to Blow Your Mind, a production of 0:00:05.640 --> 0:00:11.560 iHeart Radio. Hi. My name is Joe McCormick. And this 0:00:11.800 --> 0:00:14.840 is the Artifact, a short form series from Stuff to 0:00:14.880 --> 0:00:19.120 Blow Your Mind, focusing on particular objects, ideas, and moments 0:00:19.120 --> 0:00:26.759 in time. Glass breaks. Apart from its transparency, the brittleness 0:00:26.760 --> 0:00:30.320 of glass is its defining physical feature. And yet, since 0:00:30.360 --> 0:00:33.040 at least as far back as ancient Rome, there have 0:00:33.120 --> 0:00:36.919 been legends of a mysterious lost technology known as the 0:00:37.040 --> 0:00:43.680 vitrum flexila or vitrum malleabel, glass that can bend without breaking. 0:00:44.680 --> 0:00:48.280 The early medieval Spanish scholar Isadore of Seville wrote about 0:00:48.320 --> 0:00:52.400 this now occulted substance in a vast encyclopedic work called 0:00:52.479 --> 0:00:55.840 the Etymologies, which he compiled towards the beginning of the 0:00:55.880 --> 0:01:00.200 seventh century. According to Isadore's account, during the rain of 0:01:00.240 --> 0:01:04.080 Tiberius Caesar, there was an ingenious craftsman in Rome who 0:01:04.160 --> 0:01:08.120 invented a formula for mixing clear glass so that it 0:01:08.200 --> 0:01:12.800 was flexible and pliable at room temperature. The craftsman was 0:01:12.840 --> 0:01:15.720 brought for an audience with Caesar and presented him with 0:01:15.760 --> 0:01:19.280 a gift of a glass drinking bowl. Caesar took the 0:01:19.319 --> 0:01:23.759 bowl and threw it to the floor, but unbelievably, it 0:01:23.800 --> 0:01:27.679 did not shatter. The craftsman retrieved the bowl and showed 0:01:27.720 --> 0:01:31.080 that instead, the impact had only left a dent, as 0:01:31.120 --> 0:01:33.160 you might expect from a vessel made out of a 0:01:33.200 --> 0:01:37.240 metal like bronze. As if this wasn't amazing enough, the 0:01:37.280 --> 0:01:41.240 craftsman then produced a hammer from his tunic and proceeded 0:01:41.240 --> 0:01:45.039 to pound the dent out of the glass, restoring it 0:01:45.120 --> 0:01:48.600 to its original shape. From here i'll quote from the 0:01:48.640 --> 0:01:52.840 translation of Isadore by Stephen a Barney quote. When he 0:01:52.880 --> 0:01:56.120 had done this, Caesar said to him, does anyone else 0:01:56.200 --> 0:01:59.960 know this method of making glass? After the craftsman swore 0:02:00.120 --> 0:02:03.880 or that no one else knew, Caesar ordered him beheaded, 0:02:04.600 --> 0:02:08.600 lest if this skill became known, gold would be regarded 0:02:08.639 --> 0:02:12.239 as mud, and the value of all metals would be reduced. 0:02:12.600 --> 0:02:15.919 And it is true that if glass vessels became unbreakable, 0:02:16.240 --> 0:02:25.600 they would be better than gold and silver. Whatever you 0:02:25.680 --> 0:02:28.400 might accept about the bloody logic of the Roman emperor, 0:02:28.720 --> 0:02:31.880 there are basic physical reasons for thinking this story is 0:02:31.880 --> 0:02:35.320 probably not true. As common as it is now in 0:02:35.440 --> 0:02:38.720 beer bottles and car windshields, glass is in many ways 0:02:38.760 --> 0:02:44.639 an exquisite material. It's transparent, it's chemically nonreactive, it can 0:02:44.680 --> 0:02:47.760 be beautiful to look at when heated in a furnace. 0:02:47.800 --> 0:02:51.240 It can be molded into almost any shape, and it's 0:02:51.320 --> 0:02:55.160 usually made primarily of silica sand, which is abundant and cheap. 0:02:56.160 --> 0:02:59.040 But the major limitation of its usefulness has always been 0:02:59.120 --> 0:03:04.119 that traditional silicate glass is brittle. According to Lowther wonder Check, 0:03:04.240 --> 0:03:08.880 writing for the journal Science in quote, today's glass products 0:03:08.919 --> 0:03:12.920 reach only a fraction of the predicted intrinsic strength because 0:03:13.120 --> 0:03:17.320 of their brittleness. Wonder Check explains that the main reason 0:03:17.360 --> 0:03:21.160 that glass breaks instead of bending is that mechanical energy 0:03:21.200 --> 0:03:25.160 delivered into glass, usually quote, accumulates in the vicinity of 0:03:25.280 --> 0:03:30.840 microscopic flaws and defects. This process leads to local stress concentration, 0:03:31.160 --> 0:03:35.040 which increases with the sharpness of the tip of the flaw. Thus, 0:03:35.120 --> 0:03:37.760 the locally acting stress can be much higher than the 0:03:37.800 --> 0:03:41.760 externally applied one, and the material fails even when supporting 0:03:41.840 --> 0:03:44.960 only a low load. It doesn't seem likely to me 0:03:45.160 --> 0:03:47.600 that an inventor in the ancient world would have found 0:03:47.600 --> 0:03:50.640 a way around this brittleness, unless the substance they were 0:03:50.640 --> 0:03:55.120 talking about was not actually glass. Aside from the brute 0:03:55.160 --> 0:03:59.120 physical implausibility of this story, there's some other compelling reasons 0:03:59.160 --> 0:04:02.240 to think it's proudly nothing more than a misinterpreted rumor 0:04:02.400 --> 0:04:06.040 or fantasy. The earliest versions of the legend crop up 0:04:06.080 --> 0:04:10.640 in first century CE sources like the Satiricon of Petronius, 0:04:10.640 --> 0:04:14.200 where it appears in the explicit context of fiction. The 0:04:14.240 --> 0:04:18.159 Satiricon is a sort of absurdest comic novel, involving lots 0:04:18.200 --> 0:04:23.520 of crude sexual humor and vignettes about werewolves and cannibalism. 0:04:23.560 --> 0:04:26.760 The story of flexible glass is also told by Plenty 0:04:26.720 --> 0:04:30.880 of the Elder in his first century Encyclopedia The Natural History. 0:04:31.279 --> 0:04:35.200 One of Isadore's sources, Plenty rights that after the invention 0:04:35.320 --> 0:04:39.800 was revealed quote, the manufactory of the artist was totally destroyed, 0:04:39.920 --> 0:04:42.600 we are told, in order to prevent the value of copper, 0:04:42.960 --> 0:04:47.279 silver and gold from being depreciated. I assume the logic 0:04:47.320 --> 0:04:49.800 complied in the story is that Tiberius would have been 0:04:49.839 --> 0:04:53.400 concerned that if glass were just as malleable as gold 0:04:53.440 --> 0:04:57.240 and silver, the accumulated fortunes in those medals belonging to 0:04:57.279 --> 0:05:00.880 the rich people of Rome, including Tiberius him self would 0:05:00.880 --> 0:05:03.920 become worthless. In other words, you could think of this 0:05:03.960 --> 0:05:08.240 as an early form of science fiction, utopian or dystopian, 0:05:08.440 --> 0:05:12.360 depending on your perspective about how a technological change could 0:05:12.400 --> 0:05:14.800 have led to a revolution in the class structure of 0:05:14.800 --> 0:05:19.880 an empire. But whatever the political implications, Plenty expresses skepticism 0:05:19.920 --> 0:05:23.799 about the story, writing that it's often repeated without much evidence. 0:05:24.600 --> 0:05:27.479 But despite Plenty's doubts, the idea of glass that could 0:05:27.560 --> 0:05:31.719 bend without breaking had a tenacious legacy. Malleable glass would 0:05:31.720 --> 0:05:34.599 become one of the enduring obsessions of the alchemists of 0:05:34.640 --> 0:05:37.840 the Middle Ages through the Renaissance in the early Modern period, 0:05:38.160 --> 0:05:40.880 though many of them never made an explicit connection to 0:05:40.920 --> 0:05:44.600 the story of Tiberius in the Lost Technology. In a 0:05:45.600 --> 0:05:50.359 article for Renaissance quarterly called Storied Objects, Scientific Objects and 0:05:50.440 --> 0:05:55.320 Renaissance Experiment the Case of malleable Glass, author Vera Keller 0:05:55.440 --> 0:05:58.360 writes that from around the time of the thirteenth century, 0:05:58.760 --> 0:06:01.680 the power of making alleable glass was one of the 0:06:01.760 --> 0:06:06.160 wonders attributed to the Philosopher's Stone, while on the other hand, 0:06:06.440 --> 0:06:11.080 straightforward recipes for softening glass appeared in several books of 0:06:11.160 --> 0:06:15.839 secret knowledge between the thirteen and eighteen centuries. These recipes 0:06:15.880 --> 0:06:19.160 often claimed that if followed, glass could be made soft 0:06:19.320 --> 0:06:24.200 like leather, cloth, or even dough. Many of the recipes 0:06:24.240 --> 0:06:26.919 call for the blood of a goat, while one mentioned 0:06:26.960 --> 0:06:29.839 in a footnote by Keller calls for immersing glass in 0:06:29.880 --> 0:06:33.919 the oil of horse hoofs. Despite the great effort poured 0:06:33.960 --> 0:06:37.640 into discovering the lost secret of malleable glass, it always 0:06:37.640 --> 0:06:41.800 eluded us. However, today it looks like we may becoming 0:06:41.920 --> 0:06:46.120 full circle on the promise of vitrum flexila. Of course, 0:06:46.160 --> 0:06:49.120 since the plastics revolution of the twentieth century, we've had 0:06:49.200 --> 0:06:52.799 lots of polymer based consumer materials that are both flexible 0:06:52.920 --> 0:06:56.280 and transparent, though that material may not always have the 0:06:56.320 --> 0:06:59.680 exact properties of silicate glass. And even when you're talking 0:06:59.720 --> 0:07:03.719 about genuine glass, there are researchers working hard to make 0:07:03.760 --> 0:07:07.480 it bend without breaking, often in the context of designing 0:07:07.600 --> 0:07:11.440 screens for current and upcoming models of phones that can 0:07:11.480 --> 0:07:15.760 fold like a wallet without cracking their screens. These innovations 0:07:15.800 --> 0:07:19.480 in foldable glass are explored in a February article for 0:07:19.520 --> 0:07:22.400 The Verge by Sean Hollister, who quotes m I T 0:07:22.560 --> 0:07:26.720 Associate Professor of material Science J. J. Who and explaining 0:07:26.760 --> 0:07:29.640 that there are two main tricks to making glass that 0:07:29.720 --> 0:07:33.480 can bend like plastic. One of those tricks takes us 0:07:33.480 --> 0:07:37.040 back to what I mentioned already about microscopic flaws and 0:07:37.120 --> 0:07:40.240 defects in the structure of the glass that allow cracks 0:07:40.280 --> 0:07:44.400 to propagate. Researchers are trying to prevent the formation of 0:07:44.440 --> 0:07:47.880 these tiny flaws through the use of special chemical baths 0:07:47.880 --> 0:07:51.800 and heat treatment during the manufacturing process. But the second 0:07:51.800 --> 0:07:55.720 trick is thinness. While glass the thickness of a window 0:07:55.760 --> 0:07:59.640 pane will probably always shatter before it bends, glass less 0:07:59.640 --> 0:08:02.000 than a under in microns thick which is about the 0:08:02.000 --> 0:08:05.120 width of a human hair, can fold a surprising amount, 0:08:05.480 --> 0:08:08.040 and once the thickness is down to a few tens 0:08:08.080 --> 0:08:11.760 of microns, researchers claim that the glass can fold almost 0:08:11.840 --> 0:08:15.559 flat upon itself without breaking and without a large hinge gap, 0:08:15.880 --> 0:08:19.160 which is what the manufacturers of these phones ultimately want. 0:08:19.840 --> 0:08:22.160 And one of my favorite details is that some of 0:08:22.200 --> 0:08:26.680 the new flexible glass could be created with alternative chemical compositions, 0:08:26.960 --> 0:08:29.800 by making the glass not out of silica, but out 0:08:29.800 --> 0:08:33.880 of materials like aluminum oxide, which in its condensed crystalline 0:08:33.920 --> 0:08:45.080 form is what makes a Sapphire. Tune into new editions 0:08:45.080 --> 0:08:48.800 of the Artifact every Wednesday, hosted by either Robert or myself. 0:08:49.320 --> 0:08:52.560 As always, you can email us at contact at stuff 0:08:52.600 --> 0:09:03.200 to Blow your Mind dot com. Stuff to Blow Your 0:09:03.200 --> 0:09:06.319 Mind is production of iHeartRadio. For more podcasts from my 0:09:06.360 --> 0:09:09.400 Heart Radio, visit the iHeart Radio app, Apple Podcasts, or 0:09:09.440 --> 0:09:11.160 wherever you listen to your favorite shows.