Archive for the ‘ How? ’ Category

Why Do Computers Crash?

It turns out that humans are to blame for computer crashes. These involuntary shutdowns typically result from glitches in software – code written by human programmers.

“This code can contain many, many bugs, and these bugs can manifest themselves every now and then to cause program crashes,” said Junfeng Yang, professor of computer science at Columbia University.

Software such as Microsoft Word contains code that gives the computer a set of instructions to, say, store data in a certain place. But if one of the memory cells is corrupt (for example, contains a scratch), and the computer doesn’t know what to do, it freezes up or crashes.

Imagine if you told a friend (one with the intelligence of a machine) to go to a hardware store to buy fruit.

“This guy goes there and finds out there’s no such thing there,” Yang said. “Because it’s a machine, it doesn’t have the intelligence to do something else, maybe go to a different store to buy it.”

Software bugs can also cause problems with a computer’s operating system – which is the key piece of software that manages the hardware as well as other applications. When the operating system has problems, the entire computer can freeze and crash.

Computer scientists such as Yang are working on ways to catch software bugs before they corrupt your computer.

Similar to, yet much more complicated than, the spell check tools that catch typos and misspellings, bug checkers would automatically find glitches in software and report them to developers before software is released to the public, Yang said.

A separate issue which could cause your computer to crash – or worse, to completely die – is the virus. Viruses are programs which seem harmless, but actually contain code to corrupt your computer. These bugs can spread from one computer to the next, just like the viruses that spread between people.


Friendship Algorithm

This is from the CBS show The Big Bang Theory. Dr. Sheldon Cooper is trying to make a friend. He displays his friendship algorithm as a flow chart, and tests it.

The first pic is the flow chart that he created (but with an infinite loop), and the second pic shows the modification (LOA = Least Objective Activity). Also included is the video clip of it as well.

This is the The Friendship Algorithm

Why Do We Send Christmas Cards?

There’s a reason that Christmas is the busiest holiday season for the U.S. Postal Service – everyone is mailing out their holiday greeting cards. But from where did this tradition originate?

People have been sending each other letters and cards wishing each other well and marking special occasions since mail carriers rode stallions and carried swords, but specifically, the Christmas card custom began in early 19th-century England.

During that time, it was common for British students to send their parents progress reports of sorts as Christmas approached. They boasted about their good grades and showed off their penmanship, composition and artwork, according to “The Complete Christmas Book” (F. Watts, Inc., 1958). The students hoped that the joyful, flashy letters would entice parents to give them presents and money as rewards for the year’s efforts.

These letters served as an early combination of today’s bragging Christmas newsletters (“This year we accomplished this and that…”) and pleading letters to Santa (“I’ve been good this year! Give me the presents I want!”). But Christmas cards only began to truly come into fashion after they began to be printed and marketed as such.

“In 1839, shortly after the introduction of the penny post in England, the true Christmas card tradition of sending cards to friends and relatives developed,” according to “Holiday Folklore, Phobias, and Fun.” “One thousand copies of the card designed for Sir Henry Cole were sold. Usually regarded as the first of its kind, it was made by J.C. Horsley, a member of the Royal Academy.”

Billions of Horsley’s card designs were sent out in the years that followed, and reprints of his famous holiday greeting cards can still be bought to this day.

History of Christmas Trees

How It All Got Started

Long before the advent of Christianity, plants and trees that remained green all year had a special meaning for people in the winter. Just as people today decorate their homes during the festive season with pine, spruce, and fir trees, ancient peoples hung evergreen boughs over their doors and windows. In many countries it was believed that evergreens would keep away witches, ghosts, evil spirits, and illness.

In the Northern hemisphere, the shortest day and longest night of the year falls on December 21 or December 22 and is called the winter solstice. Many ancient people believed that the sun was a god and that winter came every year because the sun god had become sick and weak. They celebrated the solstice because it meant that at last the sun god would begin to get well. Evergreen boughs reminded them of all the green plants that would grow again when the sun god was strong and summer would return.

The ancient Egyptians worshipped a god called Ra, who had the head of a hawk and wore the sun as a blazing disk in his crown. At the solstice, when Ra began to recover from the illness, the Egyptians filled their homes with green palm rushes which symbolized for them the triumph of life over death.

Early Romans marked the solstice with a feast called the Saturnalia in honor of Saturn, the god of agriculture. The Romans knew that the solstice meant that soon farms and orchards would be green and fruitful. To mark the occasion, they decorated their homes and temples with evergreen boughs. In Northern Europe the mysterious Druids, the priests of the ancient Celts, also decorated their temples with evergreen boughs as a symbol of everlasting life. The fierce Vikings in Scandinavia thought that evergreens were the special plant of the sun god, Balder.

Germany is credited with starting the Christmas tree tradition as we now know it in the 16th century when devout Christians brought decorated trees into their homes. Some built Christmas pyramids of wood and decorated them with evergreens and candles if wood was scarce. It is a widely held belief that Martin Luther, the 16th-century Protestant reformer, first added lighted candles to a tree. Walking toward his home one winter evening, composing a sermon, he was awed by the brilliance of stars twinkling amidst evergreens. To recapture the scene for his family, he erected a tree in the main room and wired its branches with lighted candles.

Most 19th-century Americans found Christmas trees an oddity. The first record of one being on display was in the 1830s by the German settlers of Pennsylvania, although trees had been a tradition in many German homes much earlier. The Pennsylvania German settlements had community trees as early as 1747. But, as late as the 1840s Christmas trees were seen as pagan symbols and not accepted by most Americans.

It is not surprising that, like many other festive Christmas customs, the tree was adopted so late in America. To the New England Puritans, Christmas was sacred. The pilgrims’s second governor, William Bradford, wrote that he tried hard to stamp out “pagan mockery” of the observance, penalizing any frivolity. The influential Oliver Cromwell preached against “the heathen traditions” of Christmas carols, decorated trees, and any joyful expression that desecrated “that sacred event.” In 1659, the General Court of Massachusetts enacted a law making any observance of December 25 (other than a church service) a penal offense; people were fined for hanging decorations. That stern solemnity continued until the 19th century, when the influx of German and Irish immigrants undermined the Puritan legacy.

In 1846, the popular royals, Queen Victoria and her German Prince, Albert, were sketched in the Illustrated London News standing with their children around a Christmas tree. Unlike the previous royal family, Victoria was very popular with her subjects, and what was done at court immediately became fashionable—not only in Britain, but with fashion-conscious East Coast American Society. The Christmas tree had arrived.

By the 1890s Christmas ornaments were arriving from Germany and Christmas tree popularity was on the rise around the U.S. It was noted that Europeans used small trees about four feet in height, while Americans liked their Christmas trees to reach from floor to ceiling.

The early 20th century saw Americans decorating their trees mainly with homemade ornaments, while the German-American sect continued to use apples, nuts, and marzipan cookies. Popcorn joined in after being dyed bright colors and interlaced with berries and nuts. Electricity brought about Christmas lights, making it possible for Christmas trees to glow for days on end. With this, Christmas trees began to appear in town squares across the country and having a Christmas tree in the home became an American tradition.
Rockefeller Center Christmas Tree

The Rockefeller Center tree is located at Rockefeller Center, west of Fifth Avenue from 47th through 51st Streets in New York City.

The Rockefeller Center Christmas Tree dates back to the Depression Era days. The tallest tree displayed at Rockefeller Center came in 1948 and was a Norway Spruce that measured in at 100 feet tall and hailed from Killingworth, Connecticut.

The first tree at Rockefeller Center was placed in 1931. It was a small unadorned tree placed by construction workers at the center of the construction site. Two years later, another tree was placed there, this time with lights. These days, the giant Rockefeller Center tree is laden with over 25,000 Christmas lights.

Christmas Trees Around the World

German settlers migrated to Canada from the United States in the 1700s. They brought with them many of the things associated with Christmas we cherish today—Advent calendars, gingerbread houses, cookies—and Christmas trees. When Queen Victoria’s German husband, Prince Albert, put up a Christmas tree at Windsor Castle in 1848, the Christmas tree became a tradition throughout England, the United States, and Canada.

In most Mexican homes the principal holiday adornment is el Nacimiento (Nativity scene). However, a decorated Christmas tree may be incorporated in the Nacimiento or set up elsewhere in the home. As purchase of a natural pine represents a luxury commodity to most Mexican families, the typical arbolito (little tree) is often an artificial one, a bare branch cut from a copal tree (Bursera microphylla) or some type of shrub collected from the countryside.

The Norway spruce is the traditional species used to decorate homes in Britain. The Norway spruce was a native species in the British Isles before the last Ice Age, and was reintroduced here before the 1500s.

Christmas trees are imported, as no trees live this far north. They are decorated with candles and bright ornaments.

The Christmas tree has joined the “Nacimiento” (Nativity scene) as a popular ornament because of the large German population in Guatemala. Gifts are left under the tree on Christmas morning for the children. Parents and adults do not exchange gifts until New Year’s Day.

Although Christmas falls during the summer in Brazil, sometimes pine trees are decorated with little pieces of cotton that represent falling snow.

Christmas trees are bought anytime in December and decorated with colored lights, tinsel, and baubles. Some people favor the angel on top of the tree, others the star. The house is decorated with garlands, candles, holly, and ivy. Wreaths and mistletoe are hung on the door.

Most people buy Christmas trees well before Christmas Eve, but it’s not common to take the tree inside and decorate it until just a few days before. Evergreen trees are decorated with stars, sunbursts, and snowflakes made from straw. Other decorations include colorful wooden animals and straw centerpieces.

Nowadays Norwegians often take a trip to the woods to select a Christmas tree, a trip that their grandfathers probably did not make. The Christmas tree was not introduced into Norway from Germany until the latter half of the 19th century; to the country districts it came even later. When Christmas Eve arrives, there is the decorating of the tree, usually done by the parents behind the closed doors of the living room, while the children wait with excitement outside. A Norwegian ritual known as “circling the Christmas tree” follows, where everyone joins hands to form a ring around the tree and then walk around it singing carols. Afterwards, gifts are distributed.

Celebrated on December 25th by Catholics and on January 7th by Orthodox Christians, Christmas is the most popular holiday in the Ukraine. During the Christmas season, which also includes New Year’s Day, people decorate fir trees and have parties.

A popular Christmas custom is Catalonia, a lucky strike game. A tree trunk is filled with goodies and children hit at the trunk trying to knock out the hazel nuts, almonds, toffee, and other treats.

In Italy, the presepio (manger or crib) represents in miniature the Holy Family in the stable and is the center of Christmas for families. Guests kneel before it and musicians sing before it . The presepio figures are usually hand-carved and very detailed in features and dress. The scene is often set out in the shape of a triangle. It provides the base of a pyramid-like structure called the ceppo. This is a wooden frame arranged to make a pyramid several feet high. Several tiers of thin shelves are supported by this frame. It is entirely decorated with colored paper, gilt pine cones, and miniature colored pennants. Small candles are fastened to the tapering sides. A star or small doll is hung at the apex of the triangular sides. The shelves above the manger scene have small gifts of fruit, candy, and presents. The ceppo is in the old Tree of Light tradition which became the Christmas tree in other countries. Some houses even have a ceppo for each child in the family.

Many Christmas traditions practiced around the world today started in Germany.

It has been long thought that Martin Luther began the tradition of bringing a fir tree into the home. According to one legend, late one evening Martin Luther was walking home through the woods and noticed how beautifully the stars shone through the trees. He wanted to share the beauty with his wife so he cut down a fir tree and took it home. Once inside he placed small lighted candles on the branches and said that it would be a symbol of the beautiful Christmas sky. Hence, the Christmas tree.

Another legend says that in the early 16th century, people in Germany combined two customs that had been practiced in different countries around the globe. The Paradise tree (a fir tree decorated with apples) represented the Tree of Knowledge in the Garden of Eden. The Christmas Light, a small, pyramid-like frame, usually decorated with glass balls, tinsel, and a candle on top, was a symbol of the birth of Christ as the Light of the World. Changing the tree’s apples to tinsel balls and cookies; and combining this new tree with the Light placed on top, the Germans created the tree that many of us know now.

Today, the Tannenbaum (Christmas tree) is traditionally decorated in secret with lights, tinsel, and ornaments by the mother and is lit and revealed on Christmas Eve with cookies, nuts, and gifts under its branches.

South Africa
Christmas is a summer holiday in South Africa. Although Christmas trees are not common, windows are often draped with sparkling cotton wool and tinsel.

Saudi Arabia
Christian Americans, Europeans, Indians, Filipinos, and others living here have to celebrate Christmas privately in their homes. Christmas lights are generally not tolerated. Most families place their Christmas trees somewhere inconspicuous.

Fresh pine trees are too expensive for many Filipinos, so handmade trees in an array of colors and sizes are often used. Star lanterns, or parol, appear everywhere in December. They are made from bamboo sticks, covered with brightly colored rice paper or cellophane, and usually feature a tassel on each point. There is usually one in every window, each representing the Star of Bethlehem.

Of the small percentage of Chinese who do celebrate Christmas, most erect artificial trees decorated with spangles and paper chains, flowers, and lanterns. Christmas trees are called “trees of light.”

For most of the Japanese who celebrate Christmas, it’s purely a secular holiday devoted to the love of their children. Christmas trees are decorated with small toys, dolls, paper ornaments, gold paper fans and lanterns, and wind chimes. Miniature candles are also put among the tree branches. One of the most popular ornaments is the origami swan. Japanese children have exchanged thousands of folded paper “birds of peace” with young people all over the world as a pledge that war must not happen again.

Christmas Tree Trivia

Christmas trees have been sold commercially in the United States since about 1850.

In 1979, the National Christmas Tree was not lighted except for the top ornament. This was done in honor of the American hostages in Iran.

Between 1887-1933 a fishing schooner called the Christmas Ship would tie up at the Clark Street bridge and sell spruce trees from Michigan to Chicagoans.

The tallest living Christmas tree is believed to be the 122-foot, 91-year-old Douglas fir in the town of Woodinville, Washington.

The Rockefeller Center Christmas tree tradition began in 1933. Franklin Pierce, the 14th president, brought the Christmas tree tradition to the White House.

In 1923, President Calvin Coolidge started the National Christmas Tree Lighting Ceremony now held every year on the White House lawn.

Since 1966, the National Christmas Tree Association has given a Christmas tree to the President and first family.

Most Christmas trees are cut weeks before they get to a retail outlet.

In 1912, the first community Christmas tree in the United States was erected in New York City.

Christmas trees generally take 6-8 years to mature.

Christmas trees are grown in all 50 states including Hawaii and Alaska.

100,000 people are employed in the Christmas tree industry.

98 percent of all Christmas trees are grown on farms.

More than 1,000,000 acres of land have been planted with Christmas trees.

77 million Christmas trees are planted each year.

On average, over 2,000 Christmas trees are planted per acre.

You should never burn your Christmas tree in the fireplace. It can contribute to creosote buildup.

Other types of trees such as cherry and hawthorns were used as Christmas trees in the past.

Thomas Edison’s assistants came up with the idea of electric lights for Christmas trees.

In 1963, the National Christmas Tree was not lit until December 22nd because of a national 30-day period of mourning following the assassination of President Kennedy.

Teddy Roosevelt banned the Christmas tree from the White House for environmental reasons.

In the first week, a tree in your home will consume as much as a quart of water per day.

Tinsel was once banned by the government. Tinsel contained lead at one time, now it’s made of plastic.

In 1984, the National Christmas Tree was lit on December 13th with temperatures in the 70s, making it one of the warmest tree lightings in history.

34 to 36 million Christmas trees are produced each year and 95 percent are shipped or sold directly from Christmas tree farms.

California, Oregon, Michigan, Washington, Wisconsin, Pennsylvania, and North Carolina are the top Christmas tree producing states.

The best selling trees are Scotch Pine, Douglas Fir, Fraser Fir, Balsam Fir, and White Pine.

Unwrapping the Miraculous Logistics Behind Operation Christmas

Let’s be honest: There is no jolly old elf with flying reindeer who slides down chimneys and leaves gifts for every good little Christian boy and girl on Earth. That’s ridiculous.

But then, where do the presents come from?

Here’s our theory: There is, in fact, a nonsupernatural Santa. It’s a transnational corporation with one mission-critical fulfillment goal: Every kid who celebrates the holiday gets a toy on Christmas eve.

Wired spoke with business process consultants, surveillance experts, shipping pros, and a former Navy SEAL to piece together the basic outlines of the operation — focusing, for purposes of this exposé, on points of service in the continental US. From command and control at the North Pole to secret manufacturing facilities in China and Eastern Europe, from the Pacific shipping lanes to the deployment of domestic-access operatives, Santa owns the silent night. With NSA surveillance tech, they see you when you’re sleeping, and they know when you’re awake. They know when you’ve been bad or good — thanks to algorithms that make Google look like Pong. You better not shout. You better not cry. Operation Santa is coming to town.

Command and Control
Why the North Pole? Originally, isolation. The old manufacturing facilities are still there for emergencies. Also, like everyone in the information business, Santa runs space-saving, stackable blade servers. Keeping them cool usually means enormous energy bills — Santa just opens the windows.


The operation’s annual budget exceeds $27 billion. Luckily, Santa has secret deals with the major Hollywood studios. In the past 25 years, Christmas-themed films have made more than $1.7 billion, and Santa gets points off the gross. But the real revenue source: several multibillion-dollar hedge funds with an average return of 20 percent.

Santa works with all the big toymakers — after all, Mattel and Hasbro plan their entire year around Christmas. That lets the organization demand — and get — input into design. Over the course of six months, 30.6 million toys, dolls, and other knockoff items are made in low-cost Chinese factories. Santa sources production to numerous firms to mask the scope of the operation.

Specialty Items
In fall, 3.4 million handmade toys — wooden puzzles, rocking horses — are shipped by rail from small manufacturers in Eastern Europe, then loaded aboard Newark, New Jerseybound container ships in Germany.

Distribution By Air
In remote locations — or in emergencies, when standard distribution procedures face delays — High Altitude/Low Opening (HALO) parachute teams move in. Crates of toys are pushed out of high-flying C-130 cargo planes.

The Naughty/Nice Algorithm

Santa has operatives inside the NSA or can hack into its systems. Spy satellites record evidence of bullying, vandalism, and other forms of naughtiness. Servers cross-check this information against phone and Internet chatter. School databases have also been infiltrated.

Shipping By Sea
In the months leading up to C-Day, eight massive ships, each carrying 6,625 containers (with 640 toys per container), make their way from ports in China to Long Beach, California, and Tacoma, Washington. It all happens early to absorb delays due to customs, tariffs, and homeland security.

Distribution By Land
At US ports, some containers are loaded onto trucks for West Coast distribution. The rest are transferred onto trains and moved to warehouses in Sparks, Nevada, where there’s plenty of space and few questions asked. From here, the containers will eventually be moved to roughly 100 distribution centers throughout the US, with a dense concentration in the northeast and south.

Christmas Eve: Home Invasion
Heavy Equipment/Light Package Emergent Response (Helper) units deliver the toys. These special-ops agents are trained for home ingress/egress. Team leaders get naughty/nice lists downloaded to their PDAs at 2300 hours, C-Day minus one. About 80,000 mobile command centers — each staffed by four agents — use jamming systems to knock out cellular communication in their target neighborhoods and temporarily cut phone and Internet lines.

Each command center supports 15 two-person Helper teams. The infiltrators, outfitted with night-vision goggles, tote a variety of gifts. Given the three-hour window to complete all deliveries, Helpers have an average of 5 minutes to get in and out. Most homes take less time; those with alarms take more. Approaching the tree, one operative scans the gifts already in place with a terahertz-wave device to avoid duplicates. The other Helper places an appropriate toy. Very naughty kids get a Zune.
The Helpers’ objective is to leave a gift for each deserving child, but never at the expense of being discovered. If encountered, children and adults alike are distracted with a cookie, gassed with a mild hypnogogic/hallucinogenic agent, and given a hypnotic suggestion that “it was all a dream.” Obviously, casualties are totally unacceptable. If a team has to evacuate in a hurry, they fling a couple of iTunes gift cards under the tree as they bug out.


The Real Roots of 7 Magical Beasts from Harry Potter

The magical beasties that inhabit Harry Potter’s world didn’t spring entirely from J. K. Rowling’s imagination. Many of them are rooted in centuries-old myths, folklore and even a few real-life freaks. Life’s Little Mysteries rounds up the Top 7 mythological beasts from the Harry Potter universe.

7. Sphinx – Featuring the body of a lion and the head of a human, the sphinx was used by ancient Egyptians to represent some of their gods. The animal was a symbol of strength, power and nobility, and so many pharaohs and queens had their likeness carved into the statue’s head and had it placed over their tombs and burial temples in order to suggest their relation to the powerful warrior goddess Sekhmet, who is depicted with a lioness head and a female body. Egyptians also believed that sphinxes guarded treasure, and that’s just what they do in the Harry Potter universe, standing watch over Gringotts Wizarding Bank.

6. Werewolves – Werewolves run amok in the Harry Potter books, and although the series depicts good and evil werewolves, most that turn up in folktales around the world are primarily evil. One of the first mentions comes from Greek mythology, when King Lycaeon served a platter of raw human meat to the king of the gods, Zeus. Infuriated, Zeus turned Lycaeon into a wolf. During the Middle Ages, tales of werewolves spread rapidly throughout Europe as packs of wild wolves threatened peasants and their livestock. And during the 1500s in Bedburg, Germany, bodies and limbs would turn up in fields, terrifying villagers. This carried on for 25 years until the “werewolf” was caught in 1589. He was Peter Stubbe, who claimed he would become a wolf when he wore a wolf hide. He was dismembered, beheaded, and burned on a pyre Oct. 31, 1590.

5. Griffins – Griffin mythology also originated in Greece. The fearsome creature had the front legs, wings and head of a giant eagle and the body and hind legs of a lion, and served as Zeus’ watchdog. The Greeks believed that griffins originated in Asia and India, where they found gold in the high mountaintops and built nests atop the treasure. In medieval times, images of griffins decorated valuable objects that needed to be guarded, such as jewelry boxes and caskets; the creatures play a similar role in Harry Potter’s world.

4. Unicorns – In Harry Potter’s world, the unicorn is a magical horse whose single horn is used in potions and whose blood can revive someone who is “an inch from death.” Ancient Greek and Roman scholars also believed that crushed unicorn horn could cure many illnesses – although the unicorns they imagined were not just stark white, but also red and black. The myth of the unicorn resurfaced in European medieval tales, which stated that drinking from the horn would protect from poison. There’s no sign of unicorns in the fossil record, however, and the horns of allegedly caught unicorns actually belong to narwhals, which are Arctic whales that have a unicorn-horn-like tusk, or tooth, protruding from their heads. Narwals (Monodon monoceros) are currently endangered because poachers hunt them for their popular “unicorn horns.”

3. Chimera – Another creature from Greek mythology, the chimera was described in “The Iliad” as “a thing of immortal make, not human, lion-fronted and snake behind, a goat in the middle, and snorting out the breath of the terrible flame of bright fire.” Greeks believed this nasty beast spawned from an active, destructive volcano in Lycia, Asia Minor. The chimera is depicted as a monster who terrorized the Lycian countryside until she was killed by iron arrows shot by Greek hero Bellerophon. Harry Potter’s beast-wrangling friend Hagrid laments how difficult it would be to capture and raise one of the beasts. In the real world, “chimera” is a term commonly used in associated with medical experiments using human-animal cells and DNA.

2. Centaurs – Living in the Forbidden Forest near Hogwarts School of Witchcraft and Wizardry, centaurs have the four-legged body of a horse but the upper body and head of a human. Centaurs are prominent in Grecian art and have also been depicted on ancient sculptured stones found in Scotland. There is a theory that the centaur stems from confused onlookers seeing men riding horses for the first time. For example, because horses were not native to the Near East and remained rare there until after about 1800 B.C., when the Kassite nomads rode by, Near Eastern societies that had never seen such a sight may have thought that they had witnessed a man/horse hybrid.

1. Phoenix – As Albus Dumbledore’s magical familiar and defender, Fawkes the phoenix looks very similar to earlier portrayals of the everlasting bird. Legend says that the scarlet-, amber- and gold-feathered phoenix can live for 1,000 years, at which point it bursts into flame and is reborn from the ashes. The phoenix represents the immortality of the soul and is present in Roman, Greek, Egyptian, Chinese, Christian and Native American mythology. The real-life phoenix is, however, significantly less torrid – it’s a jellyfish. The hydrozoan jellyfish (Turritopsi nutricula) has cells that cycle endlessly from a mature adult stage back to an immature polyp stage — in effect regenerating its entire body over and over again.

Why Did Gold Become the Best Element for Money?

Why did gold become the standard for money? Why not copper or platinum or argon? A chemical engineer explains.

An element must meet four qualities to stand alone as a premium currency, Sanat Kumar, the chair of the chemical engineering department at Columbia University told NPR. First, it can’t be a gas — gases simply are not practical for currency exchange. That knocks out a bunch of contenders from the right side of the periodic table, including the Noble gases, which would meet the other three qualifications.

Second, it can’t be corrosive or reactive — pure lithium, for example, ignites when exposed to water or air. Iron rusts. This qualification knocks out 38 elements.

Third, it can’t be radioactive. For one thing, your money would eventually radiate away to nothing. For another, Kumar pointed out, the radiation would eventually kill you. This eliminates the two rows that are separate from table, the elements known as actinides and lanthanides.

Any of the 30 or so remaining elements would make nice, stable forms of currency if they met the fourth qualification: They must be rare enough to be valuable, but not so rare that it’s impossible to find.

That brings us to five elements, according to Kumar: rhodium, palladium, platinum, silver and gold.

Although silver has been used for currency, it tarnishes easily, so it’s out. Rhodium and palladium were discovered only in the 1800s, so they’d have been of no use to early civilizations. That leaves gold and platinum. Platinum, however, has a melting point around 3,000 degrees Fahrenheit (about 1,600 degrees Celsius), which, Kumar noted, could only be attained in a modern furnace, so early civilizations would not have been able to conveniently shape it into uniform units.

That leaves gold, which is solid but malleable, doesn’t react, and won’t kill you. It is truly the gold standard.