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Researchers read centuries-old sealed letter without ever opening it
The key? A computational flattening algorithm.
An international team of scholars has read an unopened letter from early modern Europe — without breaking its seal or damaging it in any way — using an automated computational flattening algorithm.
The team, including MIT Libraries and Computer Science and Artificial Intelligence Laboratory (CSAIL) researchers and an MIT student and alumna, published their findings today in a Nature Communications article titled, "Unlocking history through automated virtual unfolding of sealed documents imaged by X-ray microtomography."
The senders of these letters had closed them using "letterlocking," the historical process of folding and securing a flat sheet of paper to become its own envelope. Jana Dambrogio, the Thomas F. Peterson Conservator at MIT Libraries, developed letterlocking as a field of study with Daniel Starza Smith, a lecturer in early modern English literature at King's College London, and the Unlocking History research team. Since the papers' folds, tucks, and slits are themselves valuable evidence for historians and conservators, being able to examine the letters' contents without irrevocably damaging them is a major advancement in the study of historic documents.
"Letterlocking was an everyday activity for centuries, across cultures, borders, and social classes," explains Dambrogio. "It plays an integral role in the history of secrecy systems as the missing link between physical communications security techniques from the ancient world and modern digital cryptography. This research takes us right into the heart of a locked letter."
This breakthrough technique was the result of an international and interdisciplinary collaboration between conservators, historians, engineers, imaging experts, and other scholars. "The power of collaboration is that we can combine our different interests and tools to solve bigger problems," says Martin Demaine, artist-in-residence in MIT's Department of Electrical Engineering and Computer Science (EECS) and a member of the research team.
The algorithm that makes the virtual unfolding possible was developed by Amanda Ghassaei SM '17 and Holly Jackson, an undergraduate student in electrical engineering and computer science and a participant in MIT's Undergraduate Research Opportunity Program (UROP), both working at the Center for Bits and Atoms. The virtual unfolding code is openly available on GitHub.
"When we got back the first scans of the letter packets, we were instantly hooked," says Ghassaei. "Sealed letters are very intriguing objects, and these examples are particularly interesting because of the special attention paid to securing them shut."
"We're X-raying history," says team member David Mills, X-ray microtomography facilities manager at Queen Mary University of London. Mills, together with Graham Davis, professor of 3D X-ray imaging at Queen Mary, used machines specially designed for use in dentistry to scan unopened "locked" letters from the 17th century. This resulted in high-resolution volumetric scans, produced by high-contrast time delay integration X-ray microtomography.
"Who would have thought that a scanner designed to look at teeth would take us so far?" says Davis.
Computational flattening algorithms were then applied to the scans of the letters. This has been done successfully before with scrolls, books, and documents with one or two folds. The intricate folding configurations of the "locked" letters, however, posed unique technical challenges.
"The algorithm ends up doing an impressive job at separating the layers of paper, despite their extreme thinness and tiny gaps between them, sometimes less than the resolution of the scan," says Erik Demaine, professor of computer science at MIT and an expert in computational origami. "We weren't sure it would be possible."
The team's approach utilizes a fully 3D geometric analysis that requires no prior information about the number or types of folds or letters in a letter packet. The virtual unfolding generates 2D and 3D reconstructions of the letters in both folded and flat states, plus images of the letters' writing surfaces and crease patterns.
"One of coolest technical contributions of the work is a technique that explores the folded and flattened representations of a letter simultaneously," says Holly Jackson. "Our new technology enables conservators to preserve a letter's internal engineering, while still giving historians insight into the lives of the senders and recipients."
This virtual unfolding technique was used to reveal the contents of a letter dated July 31, 1697. It contains a request from Jacques Sennacques to his cousin Pierre Le Pers, a French merchant in The Hague, for a certified copy of a death notice of one Daniel Le Pers. The letter comes from the Brienne Collection, a European postmaster's trunk preserving 300-year-old undelivered mail, which has provided a rare opportunity for researchers to study sealed locked letters.
"The trunk is a unique time capsule," says David van der Linden, assistant professor in early modern history, Radboud University Nijmegen. "It preserves precious insights into the lives of thousands of people from all levels of society, including itinerant musicians, diplomats, and religious refugees. As historians, we regularly explore the lives of people who lived in the past, but to read an intimate story that has never seen the light of day — and never even reached its recipient — is truly extraordinary."
Advancing a new field
In the Nature Communications article, the team also unveils the first systematization of letterlocking techniques. After studying 250,000 historical letters, they devised a chart of categories and formats that assigns letter examples a security score. Understanding these security techniques of historical correspondence means archival collections can be conserved in ways that protect small but important material details, such as slits, locks, and creases.
"Sometimes the past resists scrutiny," explains Daniel Starza Smith. "We could simply have cut these letters open, but instead we took the time to study them for their hidden, secret, and inaccessible qualities. We've learned that letters can be a lot more revealing when they are left unopened."
The research team hopes to make a study collection of letterlocking examples available to scholars and students from a range of disciplines. The virtual unfolding algorithm could also have broad applications: Because it can handle flat, curved, and sharply folded materials, it can be used on many types of historical texts, including letters, scrolls, and books.
"What we have achieved is more than simply opening the unopenable, and reading the unreadable," says Nadine Akkerman, reader in early modern English literature at Leiden University. "We have shown how truly interdisciplinary work breaks down boundaries to investigate what neither humanities nor the sciences can hope to understand alone."
Computational tools promise to accelerate research on letterlocking as well as reveal new historical evidence. Thanks to this research, adds Rebekah Ahrendt, associate professor of musicology at Utrecht University, "we can now imagine new affective histories that physically connect the past and the present, the human and the nonhuman, the tangible and the digital."
The research team includes Jana Dambrogio, Thomas F. Peterson Conservator, MIT Libraries; Amanda Ghassaei, research engineer at Adobe Research; Daniel Starza Smith, lecturer in early modern English literature at King's College London; Holly Jackson, undergraduate student at MIT; Erik Demaine, professor in EECS; Martin Demaine, robotics engineer in CSAIL and Angelika and Barton Weller Artist-in-Residence in EECS; Graham Davis and David Mills, Queen Mary University of London's Institute of Dentistry; Rebekah Ahrendt, associate professor of musicology at Utrecht University; Nadine Akkerman, reader in early modern English literature at Leiden University; and David van der Linden, assistant professor in early modern history at Radboud University Nijmegen.
This research was supported in part by grants from the Seaver Foundation, the Delmas Foundation, the British Academy, and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek.
Why mega-eruptions like the ones that covered North America in ash are the least of your worries.
- The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
- Each eruption covered much of what is now the western United States in an ash layer several feet deep.
- The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.
The end of the world as we know it
Panoramic view of Yellowstone National Park
Image: Heinrich Berann for the National Park Service – public domain
Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.
As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).
However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.
Ash beds of North America
Ash beds deposited by major volcanic eruptions in North America.
Image: USGS – public domain
This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.
The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.
This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.
About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.
It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.
The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.
It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.
This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.
The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.
Mount St Helens
The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.
Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.
The difference between quakes and faults
The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.
Image: USGS – public domain
So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.
Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.
What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.
As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.
Strange Maps #1041
Got a strange map? Let me know at email@example.com.
Measuring a person's movements and poses, smart clothes could be used for athletic training, rehabilitation, or health-monitoring.
In recent years there have been exciting breakthroughs in wearable technologies, like smartwatches that can monitor your breathing and blood oxygen levels.
But what about a wearable that can detect how you move as you do a physical activity or play a sport, and could potentially even offer feedback on how to improve your technique?
And, as a major bonus, what if the wearable were something you'd actually already be wearing, like a shirt of a pair of socks?
That's the idea behind a new set of MIT-designed clothing that use special fibers to sense a person's movement via touch. Among other things, the researchers showed that their clothes can actually determine things like if someone is sitting, walking, or doing particular poses.
The group from MIT's Computer Science and Artificial Intelligence Lab (CSAIL) says that their clothes could be used for athletic training and rehabilitation. With patients' permission, they could even help passively monitor the health of residents in assisted-care facilities and determine if, for example, someone has fallen or is unconscious.
The researchers have developed a range of prototypes, from socks and gloves to a full vest. The team's "tactile electronics" use a mix of more typical textile fibers alongside a small amount of custom-made functional fibers that sense pressure from the person wearing the garment.
According to CSAIL graduate student Yiyue Luo, a key advantage of the team's design is that, unlike many existing wearable electronics, theirs can be incorporated into traditional large-scale clothing production. The machine-knitted tactile textiles are soft, stretchable, breathable, and can take a wide range of forms.
"Traditionally it's been hard to develop a mass-production wearable that provides high-accuracy data across a large number of sensors," says Luo, lead author on a new paper about the project that is appearing in this month's edition of Nature Electronics. "When you manufacture lots of sensor arrays, some of them will not work and some of them will work worse than others, so we developed a self-correcting mechanism that uses a self-supervised machine learning algorithm to recognize and adjust when certain sensors in the design are off-base."
The team's clothes have a range of capabilities. Their socks predict motion by looking at how different sequences of tactile footprints correlate to different poses as the user transitions from one pose to another. The full-sized vest can also detect the wearers' pose, activity, and the texture of the contacted surfaces.
The authors imagine a coach using the sensor to analyze people's postures and give suggestions on improvement. It could also be used by an experienced athlete to record their posture so that beginners can learn from them. In the long term, they even imagine that robots could be trained to learn how to do different activities using data from the wearables.
"Imagine robots that are no longer tactilely blind, and that have 'skins' that can provide tactile sensing just like we have as humans," says corresponding author Wan Shou, a postdoc at CSAIL. "Clothing with high-resolution tactile sensing opens up a lot of exciting new application areas for researchers to explore in the years to come."
The paper was co-written by MIT professors Antonio Torralba, Wojciech Matusik, and Tomás Palacios, alongside PhD students Yunzhu Li, Pratyusha Sharma, and Beichen Li; postdoc Kui Wu; and research engineer Michael Foshey.
The work was partially funded by Toyota Research Institute.
How imagining the worst case scenario can help calm anxiety.
- Stoicism is the philosophy that nothing about the world is good or bad in itself, and that we have control over both our judgments and our reactions to things.
- It is hardest to control our reactions to the things that come unexpectedly.
- By meditating every day on the "worst case scenario," we can take the sting out of the worst that life can throw our way.
Are you a worrier? Do you imagine nightmare scenarios and then get worked up and anxious about them? Does your mind get caught in a horrible spiral of catastrophizing over even the smallest of things? Worrying, particularly imagining the worst case scenario, seems to be a natural part of being human and comes easily to a lot of us. It's awful, perhaps even dangerous, when we do it.
But, there might just be an ancient wisdom that can help. It involves reframing this attitude for the better, and it comes from Stoicism. It's called "premeditation," and it could be the most useful trick we can learn.
Broadly speaking, Stoicism is the philosophy of choosing your judgments. Stoics believe that there is nothing about the universe that can be called good or bad, valuable or valueless, in itself. It's we who add these values to things. As Shakespeare's Hamlet says, "There is nothing either good or bad, but thinking makes it so." Our minds color the things we encounter as being "good" or "bad," and given that we control our minds, we therefore have control over all of our negative feelings.
Put another way, Stoicism maintains that there's a gap between our experience of an event and our judgment of it. For instance, if someone calls you a smelly goat, you have an opportunity, however small and hard it might be, to pause and ask yourself, "How will I judge this?" What's more, you can even ask, "How will I respond?" We have power over which thoughts we entertain and the final say on our actions. Today, Stoicism has influenced and finds modern expression in the hugely effective "cognitive behavioral therapy."
Helping you practice StoicismCredit: Robyn Beck via Getty Images
One of the principal fathers of ancient Stoicism was the Roman statesmen, Seneca, who argued that the unexpected and unforeseen blows of life are the hardest to take control over. The shock of a misfortune can strip away the power we have to choose our reaction. For instance, being burglarized feels so horrible because we had felt so safe at home. A stomach ache, out of the blue, is harder than a stitch thirty minutes into a run. A sudden bang makes us jump, but a firework makes us smile. Fell swoops hurt more than known hardships.
What could possibly go wrong?
So, how can we resolve this? Seneca suggests a Stoic technique called "premeditatio malorum" or "premeditation." At the start of every day, we ought to take time to indulge our anxious and catastrophizing mind. We should "rehearse in the mind: exile, torture, war, shipwreck." We should meditate on the worst things that could happen: your partner will leave you, your boss will fire you, your house will burn down. Maybe, even, you'll die.
This might sound depressing, but the important thing is that we do not stop there.
Stoicism has influenced and finds modern expression in the hugely effective "cognitive behavioral therapy."
The Stoic also rehearses how they will react to these things as they come up. For instance, another Stoic (and Roman Emperor) Marcus Aurelius asks us to imagine all the mean, rude, selfish, and boorish people we'll come across today. Then, in our heads, we script how we'll respond when we meet them. We can shrug off their meanness, smile at their rudeness, and refuse to be "implicated in what is degrading." Thus prepared, we take control again of our reactions and behavior.
The Stoics cast themselves into the darkest and most desperate of conditions but then realize that they can and will endure. With premeditation, the Stoic is prepared and has the mental vigor necessary to take the blow on the chin and say, "Yep, l can deal with this."
Catastrophizing as a method of mental inoculation
Seneca wrote: "In times of peace, the soldier carries out maneuvers." This is also true of premeditation, which acts as the war room or training ground. The agonizing cut of the unexpected is blunted by preparedness. We can prepare the mind for whatever trials may come, in just the same way we can prepare the body for some endurance activity. The world can throw nothing as bad as that which our minds have already imagined.
Stoicism teaches us to embrace our worrying mind but to embrace it as a kind of inoculation. With a frown over breakfast, try to spend five minutes of your day deliberately catastrophizing. Get your anti-anxiety battle plan ready and then face the world.
A study on charity finds that reminding people how nice it feels to give yields better results than appealing to altruism.