Who was smarter--Galileo or Mozart?

Answering that question seems impossible. After all, the former was an astronomer, the latter, a composer. Asking which of the two was smarter seems akin to forcing someone to objectively determine if apples are better than oranges. But while humans have not yet invented a scale to measure the value of fruit, we do have one that measures brain-power: the IQ test. And according to a book by Stanford psychologist Catherine Cox Miles, Galileo's IQ was around 20 points higher than Mozart's. The number may seem trivial, but if both of them were three-years-old today, competing for a slot at a private New York City preschool, Galileo would likely edge out Mozart. But should he? Is there such a thing as a true measure of something as intangible as intelligence?

The notion of assigning a numerical value to intelligence dates back to the early 20th century, when French psychologist Alfred Binet created a series of tests to help Parisian public schools identify "mentally defective" children. Between 1904 and 1911, Binet and his colleague Theodore Simon observed the skills of "average" French schoolchildren, then created a series of tests for students between the ages of three and 12 designed to assess whether their abilities were above or below the norm.

To calculate a student's "intelligence quotient," Binet and Simon simply took his mental age, divided it by his actual age, and then multiplied by 100. For example, if a seven-year-old could perform the tasks required of a nine-year-old, his IQ would be (9 / 7) *100, or around 128.

Intelligence testing reached the United States in 1916, when psychologist Lewis Terman created a new, refined intelligence scale based on the abilities of thousands of students--significantly more than the fifty or so Binet studied. Today, psychologists use a revised version of Terman's scale to evaluate children in five categories: fluid reasoning, knowledge, quantitative reasoning, visual-spatial processing and working memory. Big differences in a student's scores across these categories can help psychologists diagnose learning disabilities.

Try to answer some questions from a real IQ test yourself. Below are some examples, one from each of the five categories.

Fluid Reasoning:
1. "I knew my bag was going to be in the last place I looked, so I looked there first." What is silly or impossible about that?

Knowledge:
2. What does cryptic mean?

Quantitative Reasoning:
3. Given the numbers 3, 6, 9, 12, what number would come next?

Visual-spatial Processing:
4. Suppose that you are going east, then turn right, then turn right again, then turn left. In what direction are you facing now?

Working Memory:
5. Repeat a series of digits (forward or backward) after hearing them once.

Source: Introduction to Psychology by Dennis Coon and John O. Mitterer

Just a few years after Terman brought the IQ test to the United States, it left the classroom--and entered the military. During World War I, the number of army recruits exploded from around 200,000 in March of 1917 to over 3.5 million in November of 1918. As the military grew, so too did the need for trained officers; the most intelligent recruits needed to be identified early so they could enter officer training programs.

Thus Harvard psychologist Robert Yerkes developed the Army Alpha and Beta tests. Modeled after the Stanford-Binet scale, the tests were designed to give commanders a sense of the intelligence of the men they were leading and to screen soldiers for officer potential. Unlike Terman's IQ test, the army exams could be administered to recruits en masse and the results could be summed and interpreted without the expertise of a psychologist. During WWI, over 1.7 million men took the intelligence tests.

Think you have what it takes to be an officer? Try the questions below--they appeared on real Army alpha tests.

1. If you saw a train approaching a broken track you should:
A. telephone for an ambulance
B. signal the engineer to stop the train
C. look for a piece of rail to fit in

2. Why is beef better food than cabbage? Because:
A. it tastes better
B. it is more nourishing
C. it is harder to obtain

3. Why do some men who could afford to own a house live in a rented one? Because:
A. they don't have to pay taxes
B. they don't have to buy a rented house
C. they can make more by investing the money the house would cost

4. A dealer bought some mules for $1,200. He sold them for $1,500, making $50 on each mule. How many mules were there?

5. Unscramble the words to form a sentence. Then indicate if the sentence is true or false.
a. happy is man sick always a
b. day it snow does every not

Answers: 1.) B 2.) B 3.) C 4.) 6 5a.) False - A sick man is always happy. 5b.) True - It does not snow every day.

Sources: historymatters.com and official-asvab.com

While the tests helped educators and administrators in the early 20th century understand more about their students and recruits, they had already begun to stray from Binet's original intention. People began to use them as indicators of general aptitude, removing them from the classroom context for which they were intended. Suddenly, an absolute measure existed for a trait that had never been absolute--adding fuel to the fire of the growing eugenics movement. Rather than simply suggesting the one would have success in grade school, higher scores on Binet's test started to mean that one was more fit for breeding. The Advanced Learning Institute reported that between 1907 and 1965, thousands of people were sterilized on the basis of low scores on intelligence tests that characterized them as "feeble-minded."

In 1924, 18-year-old Carrie Buck became the first person subjected to Virginia's Eugenical Sterilization Act. She was classified as "feeble-minded" after a version of the Stanford-Binet test revealed that she had a mental age of nine. Carrie resided in the State Colony for Epileptics and Feeble-Minded in Virginia, the superintendent of which decided that she would be the first person subjected to the new law.

According to Paul Lombardo, a professor at the University of Virginia and an expert on Buck's history, others arranged a trial for Carrie to challenge the new law. Carrie was unable to convince the court of her mental capacity, but her lawyer appealed the court's decision, arguing the new law was discriminatory. The case, Buck v. Bell, went all the way to the Supreme Court, but ultimately, in 1927, the court deemed that there was nothing unconstitutional about Virginia's new law. Carrie, along with around 8,300 other Virginians, was sterilized.

It took the rise of Nazi Germany for people in the United States to recognize the horrific consequences of eugenics. But, chillingly, though the sterilization of individuals in mental institutions came to a halt in the 1970s, the Buck v. Bell decision has never officially been overruled.

Ever since writing has existed, people have wanted to send secret messages to one another--and others have wanted to intercept and read them. This is the third installment of the blog series taking you through the history of cryptography, its present, and future possibilities of unbreakable codes. Follow the links to read the first and second parts of the series.

Last time I talked about complex polyalphabetic ciphers--techniques of encoding information that make it nearly impossible to reveal the message without access to a secret key. Because the encryption processes themselves are so intricate, the main security challenge becomes keeping that key private. In order to tell a secret, you already have to share a secret key, and your encoded message will be useless if an eavesdropper finds a way to get ahold of that key.

But in 1976, Ron Rivest, Adi Shamir, and Leonard Adleman invented a method that eliminated the need to give away the key at all. Their method, public key cryptography, is still used today to make secure transmissions of sensitive data and to prove the identities of people online. Public key cryptography turns traditional cryptography on its head: instead of keeping the key a secret, every receiver creates and broadcasts his own individualized key for everyone to see, and anybody who wants to send him a message will use that key to encode it. Because of the way the key was created, he will be the only one who can decode it.

The trick to creating this kind of public key is to use what mathematicians call a one-way function: a type of math operation that's easy to do in one direction but nearly impossible to undo without additional information. One example of a one-way function is multiplying two super-big prime numbers. The multiplication part is easy, but to undo that multiplication, you need to know what the original prime numbers were. And as mathematicians can attest, factoring a number into primes is a ton of work--pick a number big enough, and it'll take all the computers in the world longer than the age of the universe to find the factors.

The RSA public-key cryptosystem that they invented (named after Rivest, Shamir, and Adleman themselves, of course) is still in use today, and it works along exactly these lines. Each person's public key is a version of a large number built from two primes, and only someone with the knowledge of the number's factors--the private key--can decode something encoded using their public key.

The other popular public key cryptosystems today work similarly. They each use a mathematically "hard problem" to create keys so that anyone can encode messages to specific people but only the intended recipients will have the extra information needed to reverse it.

Now, if people wanted to stop at this level of security it would be perfectly understandable. With the computers we have now, public key cryptography is certainly secure enough--so secure, in fact, that it's prompted governments of several countries to put limits on key size, and even to try and ban the exportation of big prime numbers. After all, governments want to be able to read everybody's mail--it wouldn't do for foreign states to have better encryption systems. Public key cryptography is the system that makes e-commerce possible, and it is a standard for high-importance confidential messages. But there is always a chance that someone will find a way to beat the system and find the extra information from the public key.

Enter the next big step, at least in theory--the quantum computer.

More on that next time.

Over the years I've had the unfortunate experience of leaving great stories on the "cutting room floor." One of them is the story of painter Anne Adams and composer Maurice Ravel, two people who lived in different countries almost a century apart yet had an extraordinary connection. Researching a documentary, especially one that explores a scientific mystery, one always takes twists and turns. Though it didn't make it into the final cut of NOVA scienceNOW's "How Smart Can We Get," the story of Adams and Ravel is one twist that has stayed with me.

Editor Jedd Ehrmann and I spent weeks looking for a way to integrate this story into the program, but alas we failed! Thanks to the internet we have the opportunity to share it with you. I hope you'll take a few minutes to watch it, then read on for more.

I came across the story while investigating a rare neurological disorder called acquired savant syndrome for NOVA scienceNOW. I knew what savant syndrome was from watching the movie "Rain Man." Dustin Hoffman plays the part of Raymond Babbitt, a savant with the uncanny ability to remember everything he's ever read. Savants have skills they never learned. Some, like the famous Kim Peek, have extraordinary memories; others, like blind, autistic savant Leslie Lemke, are natural born musicians. Leslie couldn't stand until he was 12 and didn't walk until he was 15, but at 16 he sat down at the piano and played Tchaikovsky.

Cases like these are very rare, but cases of "acquired" savant syndrome are even scarcer. Only a few dozen cases have been found to date. They were discovered by the man who gave the syndrome its name, psychiatrist Darold Treffert.

Treffert lives in Fond du Lac, in the middle of the Wisconsin countryside. He started the Savant Institute in his home office--a tiny room in his basement. The space is filled with file cabinets stuffed with documents he's collected for over 40 years. They describe the cases of over 300 savants. While collecting these stories he came across a few dozen cases of people who suddenly develop savant abilities after a head injury, acquired savants.

People like acquired savant Derek Amato. Amato, who is featured in the program, felt a sudden, compulsive desire to play piano--and, to his own surprise, found that he knew how to do so--after a concussion. Jon Sarkin became a painter after a stroke. After a brutal mugging, Jason Padgett began drawing extraordinary images based on mathematical equations.

What does Anne Adams have to do with these cases? Although Anne was not an acquired savant, she did experience a sudden burst of creativity late in life, after she was diagnosed with a rare form of dementia. MRI scans revealed what was happening in her brain as Anne's dementia progressed and her artistic ability flourished. (More about this can been seen in the program.) Treffert believes her case gives us a one-of-a-kind glimpse into how sudden abilities emerge in the injured brain.

After learning about Anne I tracked down her family in Vancouver, Canada. Her husband, Professor Robert Adams, and son Alex shared stories of how art slowly took over Anne's life. They have preserved hundreds, possibly thousands, of her paintings and drawings, which fill the walls of Alex's home. But one of their favorites was given to Dr. Bruce Miller, director of the Memory and Aging Center at the University of California, San Francisco.

Dr. Miller is the neurologist who diagnosed Anne. Over the years he has discovered a handful of patients like Anne who experienced a sudden burst of creativity during the course of the same form of dementia.

Miller was especially taken with Anne's case, and her artwork. In fact, the painting Anne's family gave him hangs in his office; it's called "Unraveling Bolero."

And this is the part of the story that hit the cutting room floor--the part that has nothing to do with acquired savant syndrome but is a fascinating tale on its own. The story of how two people who lived worlds apart are connected through the neurological changes that were taking place in their brains. Miller found their connection so fascinating that he and his colleagues wrote a paper about it. Though it didn't make it into the broadcast, I'm glad to have the opportunity to share it with you here.

Over the weekend, a new video on the internet took the world by storm. Not exactly news in itself, but who—or rather what—starred in the video makes it noteworthy.

Like most viral diversions, this latest video was a riff on another campy sensation—Gangnam Style, the K-pop music video featuring a slick-haired, doughy rapper who rides an imaginary horse across all manner of over-saturated backdrops. The new video starts with Gangnam Style's familiar bass beat, but instead of the Korean sensation Psy bouncing around the screen, there's a white clad, black-visored robot waving its arms and banging its head.

CHARLI, the robot in the video, isn't nearly as fluid as Psy, and his leg lifts are restrained compared with Psy's manic prancing. But amongst robots, CHARLI is a bona fide Michael Jackson.

Dennis Hong and his Robotics and Mechanisms Laboratory (RoMeLa) at Virginia Tech built CHARLI to study bipedalism in robots. "CHARLI's groovy dance moves were just done for fun in the lab during our 'free time,' " Hong says. In addition to dancing, the robot competes in the vaunted RoboCup, a soccer league where roboticists test the speed and agility of their creations.

To get the robot to move to the beat, Hong and his team scripted the entire dance. It was programmed frame by frame on a computer, not constructed by recording the captured motion of a human dancer. "If you simply do a 'motion capture' of a person dancing and 'playing that motion back' on a robot—which is often done in generating the motions for characters in video games or movies using computer graphics—it does not work. The robot will fall," Hong points out. That's because a robot's center of gravity, and the center of mass in each of its body parts, is different from a human being's, he says. A human moving his head, for example, will compensate differently from a robot doing the same thing.

CHARLI isn't dancing on its own yet, but the performance is still a tour de force of flexibility and dynamism. At five feet tall, CHARLI is not a small robot. Such size complicates matters greatly. For example, to flail its arms, CHARLI's actuators must be sufficiently powerful to quickly overcome the inertia. Balance is another challenge—all that mass moving around so rapidly could easily upset a less sophisticated robot, even one that's not following a motion captured human dancer.

"Balance is difficult, especially if it is moving its limbs around in high speed," Hong says. "Normally the inertial forces created by the upper body motion is considered as disturbances by the lower body, and without coordination, the robot will fall. The lower body needs to compensate for the forces created by the upper body, and vice versa." Compensating for such upper body motions is state of the art, meaning CHARLI won't be jumping around like Psy—a hallmark of the Gangnam Style video—anytime soon. But don't count out future generations of robots.

Ultimately, Hong would love to have a robot that could not only jump around, but learn to dance on its own. "For the robot to really dance—besides its capability to be able to 'enjoy' it—requires many things besides the hardware design," Hong says. He lists the challenges: It must listen to the music, track the beat, and "understand" the musical style enough to construct an appropriate dance (something even many humans can't do). Then the robot must remain balanced throughout all the motions. Finally, Hong says, "trying to create a robot that can actually 'enjoy' the dance itself, that would be the most challenging of all."

Hong, CHARLI, and some of RoMeLa's other robots will be featured in the November 14 episode of NOVA scienceNOW. Watch a sneak peek of the episode in which CHARLI scores a goal in robot soccer, another challenging feat roboticists are striving to perfect.

Families gathering around the dinner table on Thanksgiving enjoy a common food culture: roasted turkey, sweet cranberry sauce, succulent squash, fluffy stuffing, buttery potatoes, and freshly baked pumpkin pie. It's the oldest menu Americans know, and perhaps because we're aware of its origins, we don't often think about the chemistry of its components or about how science can heighten our Thanksgiving experience.

On NOVA scienceNOW's "Can I Eat That," premiering October 31, David Pogue, with the help of America's Test Kitchen, uses a dash of science to prepare several Thanksgiving dinners to ensure that everyone is full and happy by the end of the meal. Below are the exact recipes used in the show. You can use them as basic guidelines to the iconic Thanksgiving dinner, or in the interest of variety, as inspiration to deviate a little from traditional fare (via international examples or unusual twists on old favorites).

The Test Kitchen crew focused on the chemical properties of onions, turkey, and stuffing independent of one another. But to many food mixers and mashers, flavor pairing is more cutting-edge terrain. It can help answer such perennial questions as: Why does everything on the Thanksgiving table taste so good together? And why is this particular combination so satisfying?

Last December, Scientific Reports published a study that hypothesized that ingredients sharing flavor compounds are more likely to taste yummy together than ingredients that do not. Although the paper's authors acknowledged that "the scientific analysis of any art, including the art of cooking, is unlikely to be capable of explaining every aspect of the artistic creativity involved," and that how food is prepared plays an important role, they claimed that some basic flavor traits might supersede those factors.

Their "flavor network," which you can view by following this link, reveals some not-so-surprising facts about Thanksgiving food. Though cranberries and turkey are not directly connected, certain meats share flavor compounds with wine, which in turn shares flavor compounds with various fruits. Meats have strong ties to potatoes, onions, yeast, and beans. Cucumbers--which, like pumpkin and squash, belong to the Cucurbitaceae family of vegetables--share flavor compounds with butter, which is connected to meats and wheat. And it seems that apples, too, closely resemble wine in their composition.

The flavor network map exposes the way some parts of Thanksgiving dinner open up the palate and make the meal less monochromatic. Spices in pumpkin pie--cinnamon, nutmeg, cloves, and allspice--cluster in one part of the schematic near nuts, herbs, flowers, and a few vegetables but away from most of the meal's ingredients. The same holds true for cranberry sauce, which has close ties with other fruits, kelp, and some of seafood. The map might also explain optional side dishes, like shrimp, cheese dishes, and citrus elements; orange is the only fruit on the map that shares flavor compounds with nutmeg. Which brings us to the post-meal food coma. According to the study's flavor network, tea and coffee tie together the various Thanksgiving food groups--meats, spices, and alcohol. Fittingly--and perhaps unwittingly--our after-dinner customs may help tie everything together.

With the food map as a guide, you can start to concoct your own Thanksgiving meal, perhaps one with an Asian-American flair, which would balance the Western practice of pairing ingredients with shared flavor compounds with the Eastern tradition of using ingredients with more disparate flavor compounds. Such mixing and matching may be why tabouli tastes so good--its ingredients (wheat, lemon, tomato, and parsley) are scattered across the map, but all have ties to more centered ingredients like tea.

Recipes for a NOVA scienceNOW Thanksgiving

ROASTED BRINED TURKEY

Serves 10-12

This recipe is designed for a natural turkey, not treated with salt or chemicals. If using a self-basting turkey (such as a frozen Butterball) or kosher turkey, do not brine in step 1, and season with salt after brushing with melted butter in step 5. Resist the temptation to tent the roasted turkey with foil while it rests on the carving board. Covering the bird will make the skin soggy.

1 cup salt
1 (12- to 14-pound) turkey, neck, giblets, and tailpiece removed and reserved for gravy
2 onions, chopped coarse
2 carrots, peeled and chopped coarse
2 celery ribs, chopped coarse
6 sprigs fresh thyme
3 tablespoons unsalted butter, melted
1-1 1/2 cups water
1 recipe Giblet Pan Gravy

1. Dissolve salt in 2 gallons cold water in large container. Submerge turkey in brine, cover, and refrigerate or store in very cool spot (40 degrees or less) for 6 to 12 hours.

2. Set wire rack in rimmed baking sheet. Remove turkey from brine and pat dry, inside and out, with paper towels. Place turkey on prepared wire rack. Refrigerate, uncovered, for at least 8 hours or overnight.

3. Adjust oven rack to lowest position and heat oven to 400 degrees. Line V-rack with heavy-duty aluminum foil and poke holes in foil. Set V-rack in roasting pan and spray foil with vegetable oil spray.

4. Toss half of onions, half of carrots, half of celery, and thyme with 1 tablespoon melted butter in bowl and place inside turkey. Tie legs together with kitchen twine and tuck wings behind back. Scatter remaining vegetables in pan.

5. Pour water over vegetable mixture in pan. Brush turkey breast with 1 tablespoon melted butter, then place turkey breast side down on V-rack. Brush with remaining 1 tablespoon butter.

6. Roast turkey for 45 minutes. Remove pan from oven. Using 2 large wads of paper towels, turn turkey breast side up. If liquid in pan has totally evaporated, add another 1/2 cup water. Return turkey to oven and roast until breast registers 160 degrees and thighs register 175 degrees, 50 minutes to 1 hour.

7. Remove turkey from oven. Gently tip turkey so that any accumulated juices in cavity run into pan. Transfer turkey to carving board and let rest, uncovered, for 30 minutes. Carve turkey and serve with gravy.

GIBLET PAN GRAVY

Makes about six cups

Complete step 1 up to a day ahead, if desired. Begin step 3 once the bird has been removed from the oven and is resting on a carving board.

1 tablespoon vegetable oil
Reserved turkey giblets, neck, and tailpiece
1 onion, chopped
4 cups low-sodium chicken broth
2 cups water
2 sprigs fresh thyme
8 sprigs fresh parsley
3 tablespoons unsalted butter
¼ cup all-purpose flour
1 cup dry white wine
Salt and pepper

1. Heat oil in Dutch oven over medium heat until shimmering. Add giblets, neck, and tailpiece and cook until golden and fragrant, about 5 minutes. Stir in onion and cook until softened, about 5 minutes. Reduce heat to low, cover, and cook until turkey parts and onion release their juices, about 15 minutes. Stir in broth, water, thyme, and parsley, bring to boil, and adjust heat to low. Simmer, uncovered, skimming any impurities that may rise to surface, until broth is rich and flavorful, about 30 minutes longer. Strain broth into large container and reserve giblets. When cool enough to handle, chop giblets. Refrigerate giblets and broth until ready to use. (Broth can be stored in refrigerator for up to 1 day.)

2. While turkey is roasting, return reserved turkey broth to simmer in saucepan. Melt butter in separate large saucepan over medium-low heat. Add flour and cook, whisking constantly (mixture will froth and then thin out again), until nutty brown and fragrant, 10 to 15 minutes. Vigorously whisk all but 1 cup of hot broth into flour mixture. Bring to boil, then continue to simmer, stirring occasionally, until gravy is lightly thickened and very flavorful, about 30 minutes longer. Set aside until turkey is done.

3. When turkey has been transferred to carving board to rest, spoon out and discard as much fat as possible from pan, leaving caramelized herbs and vegetables. Place pan over 2 burners set on medium-high heat. Return gravy to simmer. Add wine to pan of caramelized vegetables, scraping up any browned bits. Bring to boil and cook until reduced by half, about 5 minutes. Add remaining 1 cup turkey broth, bring to simmer, and cook for 15 minutes; strain pan juices into gravy, pressing as much juice as possible out of vegetables. Stir reserved giblets into gravy and return to boil. Season with salt and pepper to taste, and serve.

BREAD STUFFING WITH FRESH HERBS

Serves 10-12

Two pounds of chicken wings can be substituted for the turkey wings. If using chicken wings, separate them into 2 sections (it's not necessary to separate the tips) and poke each segment 4 or 5 times. Also, increase the amount of broth to 3 cups, reduce the amount of butter to 4 tablespoons, and cook the stuffing for only 60 minutes (the wings should register over 175 degrees at the end of cooking). Use the meat from the cooked wings to make salad or soup.

2 pounds (20 to 22 slices) hearty white sandwich bread, cut into 1/2-inch cubes (about 16 cups)
3 pounds turkey wings, divided at joints
2 teaspoons vegetable oil
6 tablespoons unsalted butter, plus extra for baking dish
1 large onion, chopped fine
3 celery ribs, chopped fine
2 teaspoons salt
2 tablespoons minced fresh thyme
2 tablespoons minced fresh sage
1 teaspoon pepper
2 1/2 cups low-sodium chicken broth
3 large eggs
3 tablespoons chopped fresh parsley

1. Adjust oven racks to upper-middle and lower-middle positions and heat oven to 250 degrees. Spread bread cubes in even layer on 2 rimmed baking sheets. Bake until edges have dried but centers are slightly moist (cubes should yield to pressure), 45 to 60 minutes, stirring several times during baking. (Bread can be toasted up to 1 day in advance.) Transfer to large bowl and increase oven temperature to 375 degrees.

2. Use tip of paring knife to poke 10 to 15 holes in each wing segment. Heat oil in 12-inch skillet over medium-high heat until it begins to shimmer. Add wings in single layer and cook until golden brown, 4 to 6 minutes. Flip wings and continue to cook until golden brown on second side, 4 to 6 minutes longer. Transfer wings to medium bowl and set aside.

3. Return skillet to medium-high heat and add butter. When foaming subsides, add onion, celery, and 1/2 teaspoon salt. Cook, stirring occasionally, until vegetables are softened but not browned, 7 to 9 minutes. Add thyme, sage, and pepper; cook until fragrant, about 30 seconds. Add 1 cup broth and bring to simmer, using wooden spoon to scrape browned bits from bottom of pan. Add vegetable mixture to bowl with dried bread and toss to combine.

4. Grease 13 by 9-inch baking dish with butter. In medium bowl, whisk eggs, remaining 11/2 cups broth, remaining 11/2 teaspoons salt, and any accumulated juices from wings until combined. Add egg/broth mixture and parsley to bread mixture and gently toss to combine; transfer to greased baking dish. Arrange wings on top of stuffing, cover tightly with aluminum foil, and place baking dish on rimmed baking sheet.

5. Bake on lower-middle rack until thickest part of wings registers 175 degrees on instant-read thermometer, 60 to 75 minutes. Remove foil and transfer wings to dinner plate to reserve for another use. Using fork, gently fluff stuffing. Let rest 5 minutes before serving.

CLASSIC MASHED POTATOES

Serves four

Russet potatoes make fluffier mashed potatoes, but Yukon Golds have an appealing buttery flavor and can be used.

2 pounds russet potatoes
8 tablespoons unsalted butter, melted
1 cup half-and-half, warmed
Salt and pepper

1. Place potatoes in large saucepan and cover with 1 inch cold water. Bring to boil over high heat, reduce heat to medium-low, and simmer until potatoes are just tender (paring knife can be slipped in and out of potatoes with little resistance), 20 to 30 minutes. Drain.

2. Set ricer or food mill over now-empty saucepan. Using potholder (to hold potatoes) and paring knife, peel skins from potatoes. Working in batches, cut peeled potatoes into large chunks and press or mill into saucepan.

3. Stir in butter until incorporated. Gently whisk in half-and-half, add 1 1/2 teaspoons salt, and season with pepper to taste. Serve.

Ever since writing has existed, people have wanted to send secret messages to one another--and others have wanted to intercept and read them. This is the second installment of a blog series taking you through the history of cryptography, its present, and future possibilities of unbreakable codes. Click here to read Part 1: Encryptions Past.

Some of the very first secret codes were substitution ciphers--schemes for transforming the letters in a message to render them unreadable to anybody who didn't know the secret to decoding them. The reader of the message would use a "key," information that revealed how to translate the message back into normal text, that could come in the form of an exact list of letters or numbers, a code word, or another variable. In theory, only people with knowledge of the key could read the encoded messages. In practice, though, the earliest ciphers were simple enough to break by analyzing the frequency of letters or simple trial and error.

The good news for secret-keepers: In World War II, an unbreakable encryption scheme was invented. The bad news: The One-Time Pad, as it was called, never really caught on. And for good reason.

Here's how it worked. Users would need two identical copies of a long book of random numbers--the "One-Time Pad" itself. The first message sent would use the first page of the One-Time Pad, and each subsequent message would use a new page, so that by the 999th message both communicators would have gone through 999 matching pages of random numbers.

Because the numbers in the key didn't repeat, there were no patterns to analyze: hence the unbreakableness. Sure, a spy could guess the exact string of random numbers used and decode the message. But how would he know it was the right message? With a slightly different string of random numbers, the message could decode to say something completely different, and there was no way to verify a correct decoding.

Unbreakable it may have been, but the One-Time Pad was also rather inconvenient. Bulky books of random numbers were impractical to carry and use on the battlefield. There was always the risk that they would be stolen by the enemy. Even the process of generating truly random numbers was much more difficult than you'd expect, and any patterns in the numbers could be exploited to crack the code. The unbreakable One-Time Pad points to the problem with all ciphers invented up to this point--in order to send a secret message, the sender and recipient had to already share a secret: the key, whether it was a list of letters and their counterparts or a book of random numbers. And the system would only be as secure as the method used to share the key. It would be quite some time before anybody overcame that particular hurdle.

German Enigma machine. Via Wikimedia.

So far I've only talked about pen-and-ink ciphers: the kind that are easy to encrypt and transmit by hand. But the push for more complexity meant, that during World War II, armies were always on the lookout for a fast, convenient way to send out orders and information. Pen and paper gave way to simple mechanical devices, which soon blossomed into complex machines whose codes required even more complicated machines to crack. A famous example: Germany's use of the mechanical encryption system called ENIGMA to conceal its plans. ENIGMA was powerful because it was flexible: the machine's settings allowed users to access a huge number of encryption schemes based on keys that were shared among all the operators and changed by the day.

Here is how the process worked: ENIGMA sent each typed letter through three of its many scrambling rotors. At each rotor, ENIGMA switched the letter with another letter. Then, the letter went through a plugboard that could swap several letters with each other--the swap list was changed every day. After every key type, the rotors would increment forward, ensuring that the encryption of the next letter would be different. The message could only be decoded if the machine was set up with the identical rotors in the same position and the same plugboard settings--leaving 159 million million million possible "keys" or settings for a given message's beginning. (See How the Enigma Works for more about ENIGMA's inner workings.)

Because the plugboard and rotor settings were changed by all ENIGMA users on a daily basis (each ENIGMA operator had a thick book of settings to use each month), British scientists were forced to rush and break the code each day to read transmissions before the information became obsolete.

The race to break ENIGMA is a famously dramatic story. Ultimately, the scientists at Britain's Bletchley Park invented a mechanical device the size of several rooms to crack the code. Their machine was built of several pieces called bombes that recreated ENIGMA's internal machinery. These bombes automatically cycled through trying all the possible rotor combinations to break the day's transmissions. The bombes were precursors to the computers we know today; ENIGMA motivated scientific development and showed the world the possibilities of using machines to encode and transmit information.

Today, you can use a computer to create a polyalphabetic substitution code complicated enough that it would take impossibly long for someone to decode without the key. And indeed, many encryption systems available commercially rely on that basic format.

But isn't there a way to get rid of this reliance on secret keys?

Well, yes--as we'll explore next.

NOVA scienceNOW's "Can Science Stop Crime" introduced you to Tadayoshi Kohno, a University of Washington computer scientist who's made it his mission to take over networked machines, identifying surprising security holes that the bad guys can make use of. But hacking isn't just a question of guessing a password--systems use a process of encryption to mask information, making it a meaningless jumble of code unless you possess a secret key.

Ever since writing has existed, people have wanted to send secret messages to one another--and others have wanted to intercept and read them. These days, the "messages" are bank information, government files, or control over surveillance systems. The eavesdroppers have evolved into hackers and government agencies like the NSA. But the constant power struggle between secret keepers and secret stealers continues apace, spurring new invention and broadening the horizons of science along the way. Over the next week, this four-part blog series will take you through the history of cryptography, its present, and future possibilities of unbreakable codes. 

Encryptions Past

LHIEL XEU SRWP R SLNVAB VX TNO VQ XDMZ SRV DLLH XMABADIU QVWVXDIE

Ever send a secret message to a friend to avoid the snooping eyes of a younger sibling? If so, you're probably already familiar with the sort of encoding techniques I'll describe here, the earliest examples of substitution ciphers: schemes for replacing letters with others to render a message unreadable.

The first recorded examples of ciphers--specific procedures for encrypting information--replaced each letter in a message with a different letter. ("A" would always be replaced by "S," for example.) Simple versions of these ciphers were supposedly first used by Julius Caesar to transmit battle commands, and they're even sometimes called Caesar ciphers.

This sort of cipher is monoalphabetic because it assigns just one specific code letter to each letter of the alphabet in the message. It comes with a key that specifies how to change each letter to disguise the message and how to reverse the change to read it. The key could look something like:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
L A Q E F J S W B H I M P G U T X R Z O K N C Y V D

Using this key, the code LOOK BEHIND YOU would translate to MUUI AFWBGE VUK.

Of course, as these ciphers entered wide use, people quickly began to discover ways to read the message without being given the key. Look at our example--the repeated UU in the first word could only be something like EE or OO, and trying different substitutions lets you work out the original message. The longer the message, the better letter frequency analysis will work.

Secret keepers were forced to up the complexity of their codes. The result was the polyalphabetic ciphers--a method which switched the encoding process of each letter throughout the message, so "A" might be replaced with "S" at one time and then with "R" later on in the message, all according to a set pattern. The more complicated the key, the harder the message would be to figure out. However, tools like frequency analysis could still crack secret messages when the text was long enough, because the key would have to repeat--meaning some parts of the message would be encoded with the same substitutions as others.

Armies and civilian secret-keepers alike quickly took up polyalphabetic ciphers as a much more secure way to communicate. To code them quickly, senders used tools like the cipher disk in the image below. This disk was standard issue for Confederate officers during the Civil War.

A reproduction of a Confederate cipher disk. Via Wikimedia.

This Confederate cipher wheel can implement a Vigenère Cipher, which uses a key phrase or sentence to encode a message. For each letter of the raw message, you'd turn the dial so "A" on the outer circle lined up with the letter in the code phrase on the inner circle. You'd then find the letter from your message on the inner circle and substitute the matching letter on the outer circle! Rinse and repeat for each letter of the code phrase and message.

This was the state of substitution cryptography before the advent of complex calculating machines. Soon, mechanical developments would make this sort of code look like child's play.

Our blog series on cryptography will continue later this week.

It was with great pleasure when on Tuesday morning I read that Serge Haroche and Dave Wineland had been awarded the 2012 Nobel Prize in Physics "for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems."

Quantum mechanics is the branch of physics that describes how matter and energy behave at the most fundamental scale. Everything is, at its most basic, quantum-mechanical. Atoms obey the laws of quantum mechanics, and so do soccer balls. So why wasn't famed Argentine soccer player Lionel Messi also part of the citation? After all, one of the key features of quantum mechanics is the ability of a single atom to be in several places at once, and Messi can manipulate a soccer ball to similar effect. That's because atoms behave in far stranger ways than soccer balls. Over the last few decades, Haroche and Wineland have measured and manipulated individual atoms in ways that are stranger and more stirring than any World Cup soccer match.

At the beginning of the twentieth century, founders of the then new discipline named it quantum theory, after the Latin word meaning, "how much". They used the word quantum to signify phenomena that one normally thinks of as continuous, such as waves of light or of sound, that are fundamentally discrete. Light, for example, is made up of elementary excitations called photons--particles of light. Similarly, sound is composed of particles called phonons. The motions of electrons in atoms are also quantized, resulting in a discrete set of possible energy states for atoms. When an atom moves from one such energy state to another, it absorbs and emits photons and phonons. In quantum mechanics, continuous things turn out to be discrete. Conversely, things that we think of as being discrete and chunky like atoms or, for that matter, soccer balls have a continuous, wave-like quality to them. This interplay between continuous and discrete natures is known as wave particle duality.

Quantum mechanics is famously weird--its predictions are strange and counter-intuitive. A single atom can be in two places at once. A measurement made on one particle can apparently instantaneously affect another particle light years away, an effect that Schrödinger called entanglement, but that Einstein termed "spooky action at a distance." The detailed dynamics of the interaction of atoms with light and sound is a complex quantum dance replete with all sorts of quantum weirdness. As atoms absorb and emit light, they are in two different energy states at once, and the emitted photons and phonons are entangled with the atoms and with each other. Haroche and Wineland are masters at controlling and directing this herd of elementary particles.

The atom wranglers

To see exactly how deep an impression Haroche and Wineland made on our field, let's take a trip to the American West, where I was living in the summer of 1994. There, a wrangler is a cowboy whose job it is to herd horses and cattle. Cattle on the range are ornery, and it requires lots of wrangling to convince a herd to go one way or another. That summer in Santa Fe, I wasn't wrangling cattle but herds of atoms to make them exchange photons and phonons with each other. I wanted them to perform a particular task. I wanted to make the atoms compute.

Computers operate by flipping bits, the smallest possible chunks of information. A bit represents the distinction between two possible states--yes or no, true or false, zero or one. Their quantum nature makes atoms, photons, and phonons digital; they naturally represent bits. For example, an atom in its lowest energy state or ground state can be taken to represent zero, while the same atom in its first excited energy state represents one. A polarized photon whose electric field wiggles back and forth horizontally can be taken to represent zero, while the same photon wiggling back and forth vertically represents one. The presence of a phonon can be taken to represent one, while its absence represents zero. A herd of atoms exchanging photons and phonons is basically a bunch of bits flipping back and forth. If you could wrangle that herd so that it flipped its bits in the right way, I reasoned, those flipping bits would constitute a computation.

In the 1980s, David Deutsch and Richard Feynman had come up with applications for such quantum computers, if they could only be built. In 1993, I had come up with a plan to make a herd of atoms compute. If you took that herd and zapped them with a carefully crafted string of pulses of laser light--a technique called electromagnetic resonance--then the natural interactions between the atoms would allow them to flip their bits in the form of a computation. In fact, their quantum nature would make them compute in a particularly weird way. As an atom emitted or absorbed a photon, it could be in both the ground state and the first excited state at the same time. The atoms quantum bit, or "qubit," would represent zero and one simultaneously. Interactions between atoms and light could create entanglement and spooky action at a distance.

My plan looked good on paper, as I'm sure did many a plan to take a herd of Texas cattle from Red River to Kansas along the Chisholm trail. But to put it into action, I needed a real atom wrangler, an experimentalist who could actually coax atoms and photons into doing what she or he wanted. Folks told me that the best atom wrangler around was Jeff Kimble of Caltech. So I made the trip from Santa Fe to Pasadena to meet with Jeff and his atoms.

Jeff Kimble is a tall Texan, well-known for having squeezed light harder than it had ever been squeezed before. After we shook hands, my fingers knew how that light felt. Along with Serge Haroche, Jeff is the world master at dripping atoms through optical cavities and having each atom interact strongly with an individual particle of light. Jeff looked at my plan, laughed because he knew it would be difficult to implement, and then got us down to the real business of making atoms and photons perform quantum logic. He also suggested that I head up to Colorado to talk with Dave Wineland.

For years, Dave Wineland and his group at the National Institute of Standards and Technology in Boulder had been building ion traps in order to make more accurate atomic clocks. But when he saw a proposal in 1995 by two brilliant theorists at the University of Innsbruck, Ignacio Cirac and Peter Zoller, he could make ions compute. Cirac and Zoller had come up with an alternative plan for building a quantum computer. Like my proposal, their method involved zapping atoms with lasers. In their case, however, the atoms were ions trapped by electromagnetic fields and interacting with each other by the exchange of phonons--quantized vibrations induced by the electromagnetic repulsion between the ions. Chris Monroe, a young scientist running Dave's ion trap, immediately set to work. Within just a few months, Chris and Dave had the first ion trap quantum computer up and running, performing simple quantum logic operations. When I visited them that year, they had that ion trap twisting and jumping with quanta and had lassoed ions and photons to perform all kinds of quantum weirdness.

The quantum cat's meow

Perhaps the funkiest quantum state that Wineland and his group produced was a so-called "Schrödinger's cat" state. Erwin Schrödinger, in his work of 1935 where he coined the notion of entanglement, suggested the following quantum thought experiment: Imagine an apparatus where the presence of an atom in one place triggers a sequence of events that kills a cat, while the presence of the atom in another leaves the cat alive. Now have the atom be here and there at the same time--completely allowed by the laws of quantum mechanics. The result is a cat that is simultaneously dead and alive.

In the Wild West, a sheriff tracking a bandit would put posters that read, "Wanted: dead or alive." If Schrödinger's cat had been the bandit, the bounty could have been double--it was both dead and alive at the same time. If there was any scientist who could make good on that bounty, it was Dave Wineland. In fact, with his wiry build and full moustache, Dave bears a striking resemblance to the legendary lawman Wyatt Earp. More peaceful than Earp, and kinder to animals than Schrödinger, Dave and his colleagues trained their lasers on an ion in their trap to construct a kind of "Schrödinger's kitten," a quantum of a state in which a whole herd of sound particles (phonons) is both over here (dead) and over there (alive) at the same time.

Meanwhile, in the decidedly non-wild western confines of the École normale supériure, the brilliant French scientist Serge Haroche was persuading herds of photons to be both here and there at the same time. Born in Morocco, Haroche's career was marked by a meteoric rise through France's grandes écoles. He was a true quantum wrangler--ever sensitive to the nuances and moods of the atoms--using his atom-optical Schrödinger's kittens to probe atoms' delicate relationships with their environment. The process by which a quantum system such as an atom flips between being here and there simultaneously to being here or there is called decoherence. The interaction between an atom and other atoms and photons in its surroundings causes that environment effectively to measure the position of the atom. Haroche noted that the highly non-classical quantum state of the Schrödinger's kitten caused it to be highly sensitive to decoherence.

Weird entangled states are often highly sensitive to decoherence--they lose their ability to be in two places simultaneously. This sensitivity makes quantum computation more challenging than ordinary digital computation, and that made Haroche skeptical about the possibilities of large-scale quantum computing. Interestingly, the same physics that makes some entangled states more sensitive to decoherence makes others completely insensitve. These insensitive states are the basis for quantum error correcting codes that allow quantum bits to be flipped in a way that is protected from environmental influences.

I first met Haroche at a conference in Santa Barbara in 1997, where he was declaring that sensitivity to the environment would prevent quantum computers from ever being constructed. I teased Haroche for being too much like Einstein, who had made great contributions to quantum mechanics without ever fully believing in it, a ribbing which today remains true: Haroche has made heroic contributions to the field of quantum computing without believing such computers can be built.

The quantum sensitivity Haroche identified certainly makes quantum computers hard to build, but it's also that very sensitivity that makes funky quantum phenomena such as Schrödinger's cat states the basis for hyper-sensitive detectors and measurement devices. Recently, Wineland's group and others around the world have used quantum interactions between light and atoms to produce optical-frequency atomic clocks that have the potential to be many orders of magnitude more precise than existing atomic clocks. What's bad for quantum computation is good for precision measurement--if life deals you quantum lemons, make quantum lemonade.

Back in the quantum saddle

By wrangling atoms and light, Wineland, Haroche, Kimble, and many others--Nobel laureates and not--have attained an intimacy with the quantum world as never before. These 'quantum whisperers' know how to coax atoms and photons down their weird paths because they know just how weird those paths are. You don't convince people to do things by quarreling with them. Yes, they can be moved by force, but in the end people, horses, soccer balls, and atoms attain great things only when treated with sensitivity and respect.

The 19 worst passwords, as identified by SplashData.

If your go-to password is "password" or "123456," you should probably stop reading and go change it--both topped SplashData's list of the most common passwords of 2011. The software company was able to create this list by analyzing millions of passwords that hackers had stolen and posted online. According to SplashData CEO Morgan Slain, "password" and "123456" were among the ten most common passwords in over 90% of the individual files hackers posted.

Microsoft researcher Cormac Herley, who specializes in computer security, said based on the lists of stolen passwords he has seen, he suspects that between 0.2 and 0.5 percent of all passwords are the word "password." If that's true, a hacker trying to break into 1,000 different accounts using "password" will likely gain access to between two and five of them.

If you didn't find your password in the above image, don't applaud yourself quite yet. Having a strong, hard-to-guess password can only do so much. "It's definitely better, but it's better against one particular type of attack," Herley said, referring to the "guessing attack" described above in which a hacker tries different username and password combinations to gain access to an account.

Unfortunately, hackers usually take more efficient routes. Sometimes they exploit weaknesses in applications within internet browsers to secretly install keystroke-logging software onto users' computers; other times they create seemingly-innocent websites that lure users to directly reveal their login information. "If you [inadvertently] install something that's a password stealer, it doesn't matter how strong your password is," Herley said.

To protect yourself from these types of attacks, Herley recommends that you run up-to-date software. Hackers often exploit known vulnerabilities in applications like Flash or Java, and the longer a version of a program has been available, the more likely it is that hackers have learned how to break into them. He also recommends installing antivirus software.

Hackers also target servers directly. In 2009, someone broke into the server of the social-gaming site RockYou and released over 32 million passwords, including user login information for partner sites like MySpace. Websites are supposed to encrypt passwords, meaning that rather than storing a user's actual password, they store a "hash"--the result of a specific function calculated on it. But RockYou had stored the passwords in plain text, meaning when hackers gained access to the database they found an easily exploitable list of usernames and corresponding passwords. Herley called this "really, really bad practice."

Although there is no foolproof way to protect yourself from an attack on a server, Herley said you should take measures to ensure that a breach on a low value site does not compromise their security on a more important one. Although creating new passwords for each site one uses is sound advice, in practice, people may not be able to choose unique passwords for every single account they have. Herley recommends that users rank them in order of importance--creating a unique password for one's email account is likely more important than making five different passwords for five different online magazine subscriptions.

Given the various ways in which hackers can exploit traditional password login systems, one may wonder why we still use them. Researchers have proposed and developed new ways of verifying an individual's online identity. Sites could require users to scan their fingerprints or insert personalized smart cards into specialized readers attached to their computers. But Herley said he doesn't see the new technologies replacing traditional login systems any time soon for one main reason: cost. No new technology, especially one that requires a physical device, will ever be cheaper than passwords, which essentially cost websites and users nothing.

He used Facebook's "explosive growth" as an example. The site grew to nearly one million users before it received any big investments, a feat that would have been impossible had authenticating the identity of each user cost even as little as ten cents.

Sites' continued reliance on traditional verification methods does not mean that internet security has stopped improving. Companies are constantly working behind the scenes to augment password systems, implementing new techniques of verifying user identity such as tracking the locations of the computers in which a user logs in. If a website detects something unusual--like a login on a new computer in a different country--it can boost its security by requiring the user to enter additional information, like a code that is text messaged to the number linked to the user's account.

As the methods sites use to protect users' information advance, so too will hackers' determination to crack them. But before you spiral into panic, rest assured that although a spammer might find his way into your Facebook or email accounts, most Internet users will never suffer from a devastating theft of cyber identity. Still, "Anyone who has been online for any amount of time should have their guard up," Herley said. He means you, "password" users.