String theory

Although nonperturbative techniques have progressed considerably — including conjectured complete definitions in space-times satisfying certain asymptotics — a full nonperturbative definition of the theory is still lacking. The first place winner also receives a new pickup truck. On a more mathematical level, another problem is that, like quantum field theory, much of string theory is still only formulated perturbatively (i.e., as a series of approximations rather than as an exact solution). The size of the purse determines how many mushers receive additional cash prizes. While many measurements could in principle be made that would suggest that string theory is on the right track, scientists have not at present devised a stringent "test". All mushers who finish receive at least $1049. Not finding cosmic strings would not demonstrate that string theory is fundamentally wrong — merely that the particular idea of highly stretched strings acting "cosmic" is in error. A red lantern signifying perseverance is awarded to the last musher to cross the finish line.

For example, if observing the Sun during a solar eclipse had not shown that the Sun's gravity deflected light, Einstein's general relativity theory would have been proven wrong. The "Rookie of the Year" award is given to the musher who places the best among those finishing their first Iditarod. While intriguing, these cosmological proposals fall short in one respect: testing a theory requires that the test be capable, at least in principle, of falsifying the theory. The "Golden Harness" is given to the lead dog or dogs of the winning team. They might also cause slight irregularities in the cosmic microwave background, too subtle to have been detected yet but possibly within the realm of future observability. While mushers from 14 countries have competed in Iditarod races, the 2003 and 2005 wins by the Norwegian Robert Sørlie are the only times a non-American has won the race. Superstrings, D-strings or other stringy objects stretched to intergalactic scales would radiate gravitational waves, which could presumably be detected using experiments like LIGO. Doug Swigley of Montana was the first non-Alaskan to win the race, in 1995.

For example, astronomers have also detected a few cases of what might be string-induced gravitational lensing. Butcher is the second musher to win four races, and the only musher to place in either first or second place for five straight years. Older proposals for detecting cosmic strings could now be used to investigate superstring theory. Susan Butcher withdrew from the same race after two of her dogs were killed by a moose, but became the second woman to win the race the next year, and subsequently won three of the next four races. As theorist Tom Kibble remarks, "string theory cosmologists have discovered cosmic strings lurking everywhere in the undergrowth". She was featured in Vogue, and named the Professional Sportswoman of the Year by the Women's Sports Foundation. Furthermore, modern superstring theories offer other objects which could feasibly resemble cosmic strings, such as highly elongated one-dimensional D-branes (known as "D-strings"). In 1985 Libby Riddles was the only musher to brave a blizzard, becoming the first woman to win the race.

Such a stretched string would exhibit many of the properties of the old "cosmic" string variety, making the older calculations useful again. Mary Shields was the first woman to complete the race, in 1974. Several years later, it was pointed out that the expanding Universe could have stretched a "fundamental" string (the sort which superstring theory considers) until it was of intergalactic size. Susan Butcher, Doug Swingley, and Martin Buser are the only four-time winners. If such objects did exist, they must be few and far between. In 1991 he became the only person to win five times, and the only musher to win the race in three different decades. However, further experiments — and in particular the detailed measurements of the cosmic microwave background — failed to support the cosmic-string model's predictions, and the cosmic string fell out of vogue. The first musher to win four races was Rick Swenson, in 1982.

For several years, cosmic strings were a popular model for explaining various cosmological phenomena, such as the way galaxies formed in the early Universe. The win is controversial, because while the nose of his lead dog crossed the finish line one second ahead of Rick Swenson's lead dog, Swenson's body crossed the finish line first. Originally discussed in the 1980s, cosmic strings are a different type of object than the entities of superstring theories. The closest finish was the 1978 victory by Dick Mackey. In the early 2000s, string theorists revived interest in an older concept, the cosmic string. The fastest winning time is Martin Buser's 2002 finish, in 8 days, 22 hours, 46 minutes, and 2 seconds. Eventually, scientists may be able to test string theory by observing cosmological phenomena which may be sensitive to string physics. Dick Wilmarth won the first race in 1973, in 20 days, 0 hours, 49 minutes, and 41 seconds.

Since the influence of quantum effects upon gravity only become significant at distances many orders of magnitude smaller than human beings have the technology to observe (or at roughly the Planck length, about 10^-35 meters), string theory, or any other candidate theory of quantum gravity, will be very difficult to test experimentally. Paula Kislak, President of the Association of Veterinarians for Animal Rights, has been very critical of the care the dogs receive. All these possibilities must be checked, which may take a considerable time.) These developments may be in the theory itself, such as new methods of performing calculations and deriving predictions, or they may be advances in experimental science, which make formerly ungraspable quantities measurable. Dr. It does not matter who invented the theory, "what his name is", or even how aesthetically appealing the theory may be—"if it disagrees with experiment, it's wrong." (Of course, there are subsidiary issues: something may have gone wrong with the experiment, or perhaps the person computing the consequences of the theory made a mistake. The Humane Society of the United States opposes the Iditarod for the reasons stated on http://www.hsus.org/pets/issues_affecting_our_pets/facts_about_the_iditarod.html. As Richard Feynman noted in The Character of Physical Law, the key test of a scientific theory is whether its consequences agree with the measurements taken in experiments. People for the Ethical Treatment of Animals, whose spokesperson Jennifer O'Connor says: "We're totally opposed to the race for the cruelty issues associated with it,"[3] while the ASPCA is more neutral: "General concerns arise whenever intense competition results in dogs being pushed beyond their endurance or capabilities," according to Vice President Stephen Zawistowski[4].

It is by no means the only theory currently being developed which suffers from this difficulty; any new development can pass through a stage of uncertainty before it becomes conclusively accepted or rejected. The organization gathers highlights some details of the Iditarod's history of dog deaths, illnesses and injuries, and explains some of the issues that cause them. Since string theory may not be tested in the foreseeable future, some scientists^[1] have asked if it even deserves to be called a scientific theory: it is not yet falsifiable in the sense of Popper. The most vocal critic is the Sled Dog Action Coalition, http://www.helpsleddogs.org. In this sense, string theory is still in a "larval stage": it possesses many features of mathematical interest, and it may yet become supremely important in our understanding of the Universe, but it requires further developments before it is accepted or falsified. The practice of tethering dogs on short chains, which is commonly used by mushers at checkpoints and dog drops, is also criticized. No version of string theory has yet made a prediction which differs from those made by other theories—at least, not in a way that could be checked by a currently feasible experiment. The event is still criticized by animal rights activists because dogs have died and been injured during the race.

String theory remains to be verified. In 2005, four dogs died out of the 1264 dogs entered. In principle, therefore, it is possible to deduce the nature of those extra dimensions by requiring consistency with the standard model, but this is not yet a practical possibility. Egan, and the public were outraged, so the dog procedures were established in 1975, which reduced the number of fatalities to two. In either case, gravity acting in the hidden dimensions produces other non-gravitational forces such as electromagnetism. The American Society for the Prevention of Cruelty to Animals (ASPCA), Governor William A. Because it involves mathematical objects called D-branes, this is known as a braneworld theory. In 1974, between 16 and 30 dogs died on the trail from pneumonia and dehydration.

Another possibility is that we are stuck in a 3+1 dimensional subspace of the full universe, where the "3+1" reminds us that time is a different kind of dimension than space. Dogs pull carts, or ATVs as part of their training when there is not enough snow on the ground. Like the Earth, garden hoses have an interior, a region that requires an extra dimension; however, unlike the Earth, a Calabi-Yau space has no interior.). Training starts in late summer or early fall, and intensifies between November and March; competitive teams run 2,000 miles (3,200 km) before the race. In either case, the object has two spatial dimensions. The dogs are well-conditioned athletes. A point on the hose's surface can be specified by two numbers, a distance along the hose and a distance along the circumference, just as points on the Earth's surface can be uniquely specified by latitude and longitude. Five mushers were disqualified between 1973 and 1991 when signs of mistreatment were uncovered, and one was permanently banned for a repeated pattern of physical abuse.

(Of course, everyday garden hoses exist in three spatial dimensions, but for the purpose of the analogy, its thickness is neglected and only motion on the surface of the hose is considered. The "dog procedures" bar cruel and inhumane treatment. This "extra dimension" is only visible within a relatively close range to the hose, just as the extra dimensions of the Calabi-Yau space are only visible at extremely small distances, and thus are not easily detected. Dogs that become exhausted or injured are often carried in the sled's "basket" to the next "dog-drop" site, where they are transported by the volunteer Iditarod Air Force to the veterinary station at Eagle River. If, however, one approaches the hose, one discovers that it contains a second dimension, its circumference. Mushers keep a dog diary on the trail, and have it signed by a veterinarian at each checkpoint. This is akin to the 4 macroscopic dimensions we are accustomed to dealing with every day. At least five dogs must be in harness when on the trail.

If the hose is viewed from a sufficient distance, it appears to have only one dimension, its length. Each team is composed of seven to sixteen dogs, and no more may be added during the race. A standard analogy for this is to consider multidimensional space as a garden hose. As of 2005, no musher has been banned for drug abuse[2]. Essentially these extra dimensions are compactified by causing them to loop back upon themselves. Mushers are not allow to administer drugs that mask the signs of injury, including stimulants, muscle relaxants, sedatives, anti-inflammatories, and anabolic steroids. In 7 dimensions, they are termed G₂ manifolds. On the trails, volunteer veterinarians examine the dogs heart, hydration, appetite, attitude, weight, lungs, and joints; at most of the checkpoints, and look for signs of feet and shoulder injuries, respiration problems, dehydration, diarrhea, and exhaustion.

The 6-dimensional model's resolution is achieved with Calabi-Yau spaces. All dogs are identified and tracked by microchip implants and collar tags. The first is to compactify the extra dimensions; i.e., the 6 or 7 extra dimensions are so small as to be undetectable in our phenomenal experience. Starting in 1974, all dogs are examined by veterinarians before the start of the race, who check teeth, eyes, tonsils, heart, lungs, joints, and feet; and look for signs of illegal drugs, improperly healed wounds, and pregnancy. Physicists usually solve this problem in one of two different ways. They sleep with their tail curled over their nose, which provides extra insulation once they are buried in snow. However, these models appear to contradict observed phenomena. The huskies are a northern breed that prefer weather below freezing and above -50°F (-45°C).

(see technical details in the CERN preprint "Quantum Geometry of Bosonic Strings - Revisited"). Dogs bred for marathon races weight from 45 to 55 pounds (20-25 kg), and those bred for sprinting weigh 5 to 10 pounds (2-5 kg) less, but the best competitors of both types are interchangeable. In bosonic string theories, the 26 dimensions come from the Polyakov equation . The original dogs were chosen for strength and stamina, but modern racing dogs are all mixed-breed huskies bred for speed, tough feet, endurance, good attitude, and mostly importantly the desire to run. More precisely, bosonic string theories are 26-dimensional, while superstring and M-theories turn out to involve 10 or 11 dimensions. Siberian huskies were introduced in the early 20th century and became the most popular racing breed during the AAS. The only problem is that when the calculation is done, the universe's dimensionality is not four as one may expect (three axes of space and one of time), but twenty-six. As demand for dogs skyrocketed, a black market formed at the end of the 19th century, which funneled large dogs of any breed to the gold rush.

This is roughly like saying that if an observer measures the distance between two points, then rotates by some angle and measures again, the observed distance only stays the same if the universe has a particular number of dimensions. They were soon crossbred with Alaskan huskies, hounds, setters, spaniels, German shepherds, and wolves. Technically, this happens because Lorentz invariance can only be satisfied in a certain number of dimensions. The original sled dogs were Alaskan malamutes bred from wolves by the Mahlemuit tribe, and are one of the earliest domesticated breeds known. Instead, string theory allows one to compute the number of spacetime dimensions from first principles. "Mush" is rarely used by modern teams, having been replaced by "hike" or "let's go". The reason for the unobservability of the fifth dimension (its compactness) was suggested by the Swedish physicist Oskar Klein in 1926. Applying it to dogs is a 20th century coinage; prior to that time the term was "dog driver" or "dog puncher".

The first person to add a fifth dimension to Einstein's four was the German mathematician Theodor Kaluza in 1919. The term has been used to mean "move out" by foot or snowshoes since the middle of the 19th century. Nothing in Maxwell's theory of electromagnetism or Einstein's theory of relativity makes this kind of prediction; these theories require physicists to insert the number of dimensions "by hand". "Musher" is derived from the French marche, meaning "to march", and originated among the French fur trappers in Alaska. One intriguing feature of string theory is that it predicts the number of dimensions which the universe should possess. (Sherwonit, 1991) <!-- needs to be updated with more current numbers -->. Consequently, the minimum size of a string must be related to the string tension. In comparison, only the top three finishers won more than $25,000, and only the top ten won more than $10,000.

The characteristic size of the string loop will be a balance between the tension force, acting to make it small, and the uncertainty effect, which keeps it "stretched". In 1991, the combined cost of the entry fee, dog maintenance, and transportation was estimated at between USD $10,000 and $25,000. Classical intuition suggests that it might shrink to a single point, but this would violate Heisenberg's uncertainty principle. Only a handful of professionals make their living running large kennels; most are amateurs who make their living hunting, fishing, trapping, gardening, or with seasonal jobs; though lawyers, surgeons, airline pilots, veterinarians, biologists, and CEOs have competed. Its tension will tend to contract it into a smaller and smaller loop. Most are from rural South Central Alaska, the Interior, and the "Bush"; few are urban, and only a small percentage are from the Lower 48, Canada, or overseas. Consider a closed loop of string, left to move through space without external forces. More than 50 mushers enter each year.

The tension of a quantum string is closely related to its size. Brass belt buckles and special patches are given to everyone who completes the race. For example, quantum strings have tension, much like regular strings made of twine; this tension is considered a fundamental parameter of the theory. An awards banquet is held the Sunday after the winner's arrival. While understanding the details of string and superstring theories requires considerable mathematical sophistication, some qualitative properties of quantum strings can be understood in a fairly intuitive fashion. While the winner of the first race in 1973 completed the competition in just over 20 days, preparation of the trail in advance of the dog sled teams, and improvements in dog training have dropped the winning time to under 10 days, in every race since 1996. Nowadays, 'string theory' usually refers to the supersymmetric variant while the earlier is given its full name, 'bosonic string theory'. The city's fire siren is sounded as each musher crosses the finish line.

The term 'string theory' properly refers to both the 26-dimensional bosonic string theories and to the 10-dimensional superstring theories discovered by adding supersymmetry. On the way to the arch, each musher passes down Front Street, past a saloon once owned by Wyatt Earp, and down the fenced-off 50 yard end stretch. Many recent developments in the field relate to D-branes, objects which physicists discovered must also be included in any theory which includes open strings of the super string theory. The tradition is based on the kerosene lamp lit and hung outside a roadhouse, when a musher carrying goods or mail was en route. (Several meanings of the "M" have been proposed; physicists joke that the true meaning will only be chosen when the theory is finally understood.). A "Widow's Lamp" is lit and remains hanging on the arch until the last competitor crosses the finish line. These discoveries sparked the second superstring revolution. While the old arch spelled out "End of the Iditarod Dog Race", the new arch has an additional word: "End of the Iditarod Sled Dog Race".

In the 1990s, Edward Witten and others found strong evidence that the different superstring theories were different limits of an unknown 11-dimensional theory called M-theory. The new arch is a spruce log with two distinct burls, similar but not identical to the old arch. Several other ground-breaking discoveries, such as the heterotic string, were made in 1985. The original burled arch lasted from 1975, until it was destroyed by dry rot and years of inclement weather in 2001. The anomaly is cancelled due to the Green-Schwarz mechanism. The official finish line is the Red "Fox" Olson Trail Monument, more commonly known as the "burled arch", in Nome. This first superstring revolution was started by a discovery of anomaly cancellation in type I string theory by Michael Green and John Schwarz in 1984. As of 1991, the race has been decided by less than an hour seven different times, less than five minutes three times, and in the closest race the winner and the runner-up were only one second apart.

Roughly between 1984 and 1986, physicists realized that string theory could describe all elementary particles and interactions between them, and hundreds of them started to work on string theory as the most promising idea to unify theories of physics. The last leg is crucial because the lead teams are often within a few hours of each other at this point. String theories which include fermionic vibrations are now known as superstring theories; several different kinds have been described. From White Mountain to Safety is 77 miles (124 km), and from Safety to Nome is just 22 miles (35 km). Investigating how a string theory may include fermions in its spectrum led to supersymmetry, a mathematical relation between bosons and fermions which is now an independent area of study. All teams must rest their dogs for at least six hours at White Mountain, before the final sprint. While bosons are a critical ingredient of the Universe, they are not its only constituents. After the Bay, the route swings west along the south shore of Seward Peninsula though the tiny villages of Elim, Golovin and White Mountain.

Additionally, as the name implies, the spectrum of particles contains only bosons, particles like the photon which obey particular rules of behavior. The route then passes across the frozen Norton Bay, where the markers are young spruce trees that were dropped into holes in the ice, where they froze, to Koyuk. Most importantly, the theory has a fundamental instability, believed to result in the decay of space-time itself. From Unalakleet, the route passes through the hills to the Inupiat village of Shaktoolik, which is also buried in snow, after the northeast wind brings ground blizzards. However, the bosonic theory has problems. Racers are met by church bells or sirens, and mobbed by crowds. Not all modern string theories use both types; some incorporate only the closed variety. The town's name means the "place where the east wind blows", and the buildings are commonly buried under snowdrifts.

The two types of string behave in slightly different ways, yielding two spectra. The majority of the residents are Inupiat, the Inuit people of the Bering Strait region. These early models included both open strings, which have two distinct endpoints, and closed strings, where the endpoints are joined to make a complete loop. According to the 2000 census, the village of Unalakleet has a population of 747, making it the largest Native American town along the Iditarod. The scale of notes, each corresponding to a different kind of particle, is termed the "spectrum" of the theory. Now that the race is more competitive, the last stretch has become one long dash to the finish. The mass the particle has, and the fashion with which it can interact, are determined by the way the string vibrates—in essence, by the "note" which the string sounds. In the early years of the Iditarod, the last stretch along the shores of the Norton Sound of the Bering Sea to Nome was a slow, easy trip.

By applying the ideas of quantum mechanics to the Polyakov action—a procedure known as quantization—one can deduce that each string can vibrate in many different ways, and that each vibrational state appears to be a different particle. The "Kaltag Portage" runs through a 1,000 feet (300 m) pass down to the Inuit town of Unalakleet, on the shore of the Bering Sea. Bosonic string theory is formulated in terms of the Polyakov action, a mathematical quantity which can be used to predict how strings move through space and time. Both trails meet again in Kaltag, which for hundreds of years has been a gateway between the Athapaskan villages in the Interior, and the Inuit settlements on the coast of the Bering Sea. It is now hoped that string theory or some descendant of it will provide a fundamental understanding of the quarks themselves.). A greater hazard is the uniformity of this long stretch: Suffering from sleep deprivation, many mushers report hallucinations (Sherwonit, 1991). (The original need for a viable theory of hadrons has been fulfilled by quantum chromodynamics, the theory of quarks and their interactions. Ruby and Anvik are on the longest river in Alaska, the Yukon, which is swept by strong winds which can wipe out the trail and drop the windchill below -100 °F (-75 °C).

This led to the development of bosonic string theory, which is still the version first taught to many students. From Iditarod the route goes through the Athapaskan villages of Shageluk, Anvik, Grayling, and Eagle Island. Schwarz and Scherk argued that string theory had failed to catch on because physicists had underestimated its scope. On odd years, the southern route first passes through the ghost town of Iditarod, which is the alternate halfway mark, at 599 miles (964 km) from Anchorage, and 532 miles (856 km) from Nome (ITC, Southern). Then, in 1974, John Schwarz and Joel Scherk studied the messenger-like patterns of string vibration and found that their properties exactly matched those of the gravitational force’s hypothetical messenger particle -- graviton. Ruby is another former gold rush town which became an Athapaskan village. The scientific community soon lost interest in string theory, and the standard model, with its particles and fields, remained unthreatened. From Cripple, the route passes through Sulatna Crossing to Ruby, on the Yukon River.

But even after physicists understood the physical explanation for Veneziano’s insight, the string description of the strong force made many predictions that directly contradicted experimental findings. On even years, the northern route first passes through Cripple, which is 503 miles (810 km) from Anchorage, and 609 miles (980 km) from Nome (ITC, Northern), making it the middlemost checkpoint. By representing nuclear forces as vibrating, one-dimensional strings, these physicists showed how Euler’s function accurately described those forces. The two routes differ by less than 10 miles (16 km). In 1970, Yoichiro Nambu, Holger Bech Nielsen, and Leonard Susskind unveiled the physics beneath Euler’s strictly theoretical formula. In the late 1970s, the southern leg of the route was added to give the southern villages a chance to host the Iditarod, and also to allow the route to pass through the trail's namesake, the historical town of Iditarod. Veneziano applied the Euler beta function to the strong force, but no one could explain why it worked. During the first few Iditarods there was only one trail, which followed the route of what is now the northern trail.

Veneziano found that a 200-year-old formula created by Swiss mathematician Leonhard Euler (the Euler beta function) perfectly matched modern data on the strong force. On even years, the northern route is used; and on odd years the southern route is used. In 1968, theoretical physicist Gabriele Veneziano was trying to understand the strong nuclear force when he made a startling discovery. After Ophir, the trail diverges into a northern and a southern route, which rejoin at Kaltag. No simple model of the hadron, such as picturing it as a set of smaller particles held together by spring-like forces, was able to explain these relationships. By this stage in the race, the front-runners are several days ahead of those in the back of the pack. In particle-accelerator experiments, physicists observed that the spin of a hadron is never larger than a certain multiple of the square of its energy. Ophir, named for the reputed source of King Solomon's gold by religious prospectors, is the next checkpoint.

String theory was originally invented to explain peculiarities of hadron (subatomic particle which experiences the strong nuclear force) behavior. The next checkpoint is the ghost town of Takotna, which was a commercial hub during the gold rush. . It still has a good airfield, so journalists are common. String theory has also led to insight into supersymmetric gauge theories, which will be tested at the new Large Hadron Collider experiment. McGrath is also notable for being the first site in Alaska to receive mail by aircraft (in 1924), heralding the end of the sled dog era. Work on string theory has led to advances in mathematics, mainly in algebraic geometry. According to the 2000 census, it has a population of 401, making it the largest checkpoint in the Interior.

String theory as a whole has not yet made falsifiable predictions that would allow it to be experimentally tested, though various special corners of the theory are accessible to planned observations and experiments. The route then follows the south fork of the Kuskokwim to the former mining town of McGrath. It is not yet known whether string theory is able to describe a universe with the precise collection of forces and matter that is observed, nor how much freedom to choose those details the theory will allow. Nikolai, an Athapaskan settlement on the banks of the Kuskokwim River, is the first Native American village used as a checkpoint, and the arrival of the sled teams is one of the largest social events of the year. Superstring theories include fermions, the building blocks of matter, and incorporate supersymmetry. The Burn forces teams to move very slowly, and can cause paw injuries. It is a possible solution of the quantum gravity problem, and in addition to gravity it can naturally describe interactions similar to electromagnetism and the other forces of nature. Fallen trees, and falling through clumps of sedge or grass which balloon out into a canopy two feet (600 mm) above the ground, supporting a deceptively thin crust of snow, are common dangers.

Interest in string theory is driven largely by the hope that it will prove to be a theory of everything. In 1976, a wildfire turned 360,000 acres (1,500 km) of spruce into blackened badland of burnt timber. Study of string theories has revealed that they require not just strings but other objects, variously including points, membranes, and higher-dimensional objects. About 45 miles (70 km) from Rohn, the path leaves the river and passes into the Farewell Burn. For this reason, string theories are able to avoid problems associated with the presence of pointlike particles in a physical theory. In 1973, Terry Miller and his team were almost drawn into a hole in the river by the powerful current in an overflow, but were rescued by Tom Mercer who came back to save them. String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics. In 1975, Vaughan was hospitalized for frostbite after running through an overflow.

From Rohn, the trail follows the south fork of the Kuskokwim River, where freezing water running over a layer of ice (overflow) is a hazard. The isolation, and its location immediately after the rigors of Rainy Pass, and before the 75 mile haul to the next checkpoint, makes it a popular place for mushers to take their mandatory 24 hour stop. Rohn is the next checkpoint, and is located in a spruce forest with no wind and a poor airstrip. In 1997, Ramey Smyth lost the end of his pinkie when it hit an overhanging branch while negotiating the gorge[1].

The route then follows Tatina River, which is also hazardous; in 1986 Butcher's lead dogs fell through the ice, but landed on a second layer of ice instead of falling into the river. In 1988, rookie Peryll Kyzer fell through an ice bridge into a creek, and spent the night wet. Mushers have to ride the brake most of the way down, and use a snow hook for traction. Steep and twisting, it drops 1,000 feet (300 m) in elevation in just five miles (8 km), and there is little traction so the teams are hard to control.

The trail down Dalzell Gorge from the divide is regarded as the worst stretch of the trail. Byrd's 1928 expedition to the South Pole and competed in the only Olympic sled dog race, became lost for five days after leaving Rainy Pass, and nearly died. In 1976, retired colonel Norman Vaughan, who drove a dog team in Richard E. The wind also erases the trail and markers, making the path hard to follow.

In 1974, there were several cases of frostbite when the temperature dropped to -50 Fahrenheit (-45C), and the 50 miles per hour (80 km/h) winds caused the windchill to drop to -130F (-90C). The valley up the mountains is exposed to blizzards. The elevation of the pass is 3,200 feet (975 m), and some nearby peaks exceed 5,000 feet (1,500 m). From Rainy Pass, the route continues up the mountain, past the tree line to the divide of the Alaska Range, and then passes down into the Alaska Interior.

Rainy Pass is part of the Historic Iditarod Trail, but until 1976 the pass was inaccessible and route detoured through Ptarmigan Pass, also known as Hell's Gate, because of the 1964 Good Friday Earthquake. In 1985, Jerry Austin broke a hand and two of his dogs were injured when the sled went out of control and hit a stand of trees. The stretch from Finger Lake to Rainy Pass, on Puntilla Lake, becomes more difficult, as the teams follow the narrow Happy River Gorge, where the trail balances on the side of a heavily forested incline. From Skwentna, the route follows the Skwentna River into the southern part of the Alaska Range to Finger Lake.

Skwentna is a 40 minute hop from Anchorage by aircraft, and dozens of planes land on the airstrip or on the Skwetna River, bringing journalists, photographers, and spectators. Most mushers push through the night, and the first teams usually arrive at Skwentna before dawn. Otherwise, the route to Skwentna is easy, over flat lowlands, and well marked by stakes or tripods with reflectors or flags. In 1982, Dick Mackey, Warner Vent, Jerry Austin, and their teams were driven into the forest by a charging moose, though there were no deaths.

It killed two dogs and seriously injured six more in the twenty minutes before Duane "Dewey" Halverson arrived and shot it. In 1985, Susan Butcher lost her chance at becoming the first woman to win the Iditarod when her team made a sharp turn, and encountered a pregnant moose. Moose kill more people each year than bears, and have been known to attack when starving, or when they feel threatened. As a result, the large deer use pre-existing trails, and stubbornly refuse to move, forcing mushers to make a wide half-circle through the deep snow before returning to the trail.

The many moose in the area find it difficult to move and forage for food when the ground is thick with snow. The first 100 miles (160 km) from Eagle River through the checkpoints at Knik, and Yetna Station, to Skwentna are known as "moose alley", and are one of the most hazardous stretches of the trail. While not as chaotic as the ceremonial start in Anchorage, thousands of spectators also mob the restart. The mushers depart, separated by the same intervals as their arrival at the second checkpoint.

The traditional restart location is the headquarters of the Iditarod Trail Committee, in Wasilla, but warm weather and poor trail conditions can push the restart further north to Willow Lake, and in 2003 it was bumped 300 miles (500 km) north to Fairbanks. Prior to 2004, the race was restarted at 10 A.M., but the time has been moved back so the dogs will be starting in colder weather, and the first mushers arrive at Skwentna well after dark, which reduces the crowds of fans who fly into the checkpoint. AST. After the dogs are shuttled to the third checkpoint, the race restarts the next day (Sunday) at 2 P.M.

The second checkpoint also occasionally changes due to weather; in 2005, the checkpoint was changed from Eagle River to Campbell Airstrip, only 11 miles (18 km) away. During the first two races in 1973 and 1974, the teams crossed the mudflats of Cook Inlet to Knik (the original restart location), but this was discontinued because the weather frequently hovers around freezing, turning it into a muddy hazard. Once they arrive at the Veterans of Foreign Wars building, the mushers check in, unharness their teams, return them to their boxes, and drive 30 miles (50 km) of highway to the restart point. The teams then follow Glenn Highway for 2 to 3 hours until they reach Eagle River, 20 miles (30 km) away.

They cover several miles of city streets and city trails before reaching the foothills to the east of Anchorage, in Chugach State Park in the Chugach Mountains. The mushers then continue through the city streets, where police halt traffic at intersections to allow them to pass. But despite the problems, Anchorage is the largest city situated close to the Historic Iditarod Trail, and provides access to the facilities of a full city, including press coverage. To compensate, some mushers use a lead dog more accustomed to the chaos during this first leg.

In 1979, Gayle Nienhueser fell and sprained a wrist, and in 1985 there was a three-sled pileup around a sharp curve. Teams occasionally come to a complete stop, or run into the crowds. This is the most trying portion of the race for many dogs, who are unused to the noise and flashing cameras of city crowds; or the unusual terrain including tunnels, bridges, and sharp corners. The additional riders also help curb the enthusiasm of the dogs.

In 2005, the average bid was USD $1918.09, and raised a total of $140,021.00. The Idita-Riders are chosen by an auction in January, which was held entirely online for the first time in 2005. One is a family member or friend, and the other is an "Idita-Rider". In addition to the normal load, each team also carries two passengers.

The start order is determined by a lottery during a banquet held two days prior. The first competitor leaves at 10:02, and the rest follow, separated by 2 minute intervals. From the first race in 1973 until 1980, the honorary musher was Leonhard Seppala, who covered the longest distance in the 1925 diphtheria serum run. The first musher to depart at 10AM AST is an honorary musher, selected for their contributions to dog sledding.

Shortly before the race, a ribbon cutting ceremony is held under the flags representing the home countries and states of all competitors in the race. At 8:30AM AST, the crowds of spectators are sent behind the slatwood barriers. Race officials, dog handlers, veterinarians, and journalists mob the mushers in staging area for last minute interviews and checkups. Hundreds of dogs are unloaded from "dog boxes", honeycomb-like compartments in the back of a truck, and marked with identifying paint.

Prior to 1983, the race started at Mulcahy Park. A five-block section of the street is barricaded off as a staging area, and snow is stockpiled and shipped in by truck the night before to cover the route to the first checkpoint. The race starts the first Saturday in March, at the first checkpoint on Fourth Street, in downtown Anchorage. Weather also halted the race later at McGrath, and the two stops added almost a week to the winning time.

Fifty-eight mushers and 508 dogs congregated at the small lodge in Rainy Pass for three days, while emergency shipments of food were flown in from Anchorage. In 1985, the race was suspended for the first time for safety reasons when weather prevented the Iditarod Air Force from delivering supplies to Rohn and Nikolai, the first two checkpoints in the Alaska Interior. Each team is required to stop for 6 hours at White Mountain to rest their dogs, and to spend at least 24 hours at one other checkpoint, frequently choosing Rohn. Mushers can also drop injured or exhausted dogs at most checkpoints, where they are flown to a veterinary station.

The gear includes food, extra booties for the dogs, headlamps for night travel, batteries (for the lamps, music, or radios), tools and sled parts for repairs, and even lightweight sleds for the final dash to Nome. Mushers purchase supplies and equipment in Anchorage, which are flown ahead to each checkpoint by the Iditarod Air Force. Some mushers prefer to camp on the trail and immediately press on, but others stay and rest. There are currently 25 checkpoints on the northern route, and 26 on the southern route where mushers must sign in.

The length of the race is also frequently rounded to either 1,050, 1,100, or 1,150 miles (1690, 1770 or 1850 km), but is officially set at 1,049 miles (1688 km), which honors Alaska's status as the 49th state. As a result the exact measured distance of the race varies, but according to the official website the northern route is 1,112 miles (1,790 km) long, and the southern route is 1,131 miles (1820 km) long (ITC, Southern & Northern). Checkpoints along the route are also occasionally added or dropped, and the ceremonial start of the route and the restart point are commonly adjusted due to weather. The largest changes were the addition of the restart location in 1975, and the shift from Ptarmidgan to Rainy Pass in 1976.

Aside from the addition of the southern route, the route has remained relatively constant. Passing through the historic town of Iditarod was a secondary benefit. The race used the northern route until 1977, when the southern route was added to distribute the impact of the event on the small villages in the area, none of which have more than a few hundred inhabitants. Both follow the same trail for 444 miles (715 km), from Anchorage to Ophir, where they diverge and then rejoin at Kaltag, 441 miles (710 km) from Nome.

While always longer than 1,000 miles (1,600 km), the trail is actually composed of a northern route, which is run on even-numbered years; and a southern route, which is run on odd-numbered years. The route of the race was chosen to test the mettle of the sled dogs and their drivers ("mushers"), and passes through largely unpopulated tundra. Except for the start in Anchorage, the modern race follows parts of the historic trail. The entire network of branching paths covers a total of 2,450 miles (3,945 km).

The main route of the Iditarod trail extends 938 miles (1,500 km) from Seward in the south to Nome in the northwest, and was first surveyed by Walter Goodwin in 1908, and then cleared and marked by the Alaska Road Commission in 1910 and 1911. Iditarod may be derived from the Athabaskan haiditarod, meaning "far distant place". The trail in turn is named for the town of Iditarod, which was an Athabaskan village before becoming the center of the Inland Empire's Iditarod Mining District in 1910, and then turning into a ghost town at the end of the local gold rush. The race's namesake is the Iditarod Trail, which was designated as one of the first four National Historic Trails in 1978.

While the race was originally patterned after the AAS, it has also been deliberately associated with other symbols from the history of Alaska, including Leonhard Seppala, the gold rush, and most importantly the 1925 serum run, to which it is now inseparately connected. Despite the loss of sponsors during a dog abuse scandal in 1976, the Iditarod caused a resurgence of recreational mushing in the 1970s, and has continued to grow until it is now the largest sporting event in the state. The event was a success; even though the purse dropped in the 1974 race, the popularity caused the field of mushers to rise to 44, and corporate sponsorship in 1975 put the race on secure financial footing. The first true Iditarod was held in 1973, and attracted a field 34 mushers, 22 of whom completed the race.

Redington was the impetus behind extending the race more than 1,000 miles along the historic route to Nome, and a major fund raising campaign which raised a purse of $51,000. The next race in 1968 was canceled due to lack of snow, and the small $1,000 purse in 1969 only drew 12 mushers. The purse of USD $25,000 attracted a field of 58 racers including the winner, Isaac Okleasik. With the support of Joe Redington, Senior (the "Father of the Iditarod"), the first Iditarod Trail Seppala Memorial Race was held in 1967 and covered 25 miles (40 km) near Anchorage.

Page (the "Mother of the Iditarod"), who wanted to sponsor a sled dog race to commemorate the 100th anniversary of the purchase of Alaska from Russia. The Iditarod was the brainchild of Dorothy G. Together they covered the most hazardous stretch of the route, and carried the serum further than any other team. However, most mushers consider Leonhard Seppala and his lead dog Togo to be the true heroes of the run.

The two became media celebrities, and a statue of Balto was erected at Central Park in New York City in 1925, where it has become one of the most popular tourist attractions. The Norwegian Gunnar Kaasen and his lead dog Balto, arrived on Front Street in Nome on February 2 at 5:30 AM just five and a half days later. The 20 pound (9 kg) cylinder of serum was sent by train 298 miles (480 km) from the southern port of Seward to Nenana, where it was passed just before midnight on January 27 to the first of twenty mushers and more than 100 dogs who relayed the package 674 miles (1,085 km) from Nenana to Nome. Since the two available planes were both dismantled and had never been flown in the winter, Governor Scott Bone approved a safer route.

A diphtheria epidemic threatened Nome, especially the Inuit children who had no immunity to the "white man's disease", and the nearest quantity of antitoxin was in Anchorage. The most famous event in the history of Alaskan mushing is the 1925 serum run to Nome, also known as the "Great Race of Mercy". In 1914, the Norwegian immigrant Leonhard Seppala first appeared, and went on to win race in 1915, 1916, and 1917, before the race was discontinued in 1918 during World War I. The event introduced the first Siberian huskies to Alaska in 1910, where they quickly became the favored racing dog, replacing the Alaskan malamute, and mongrels bred from imported huskies and other large breeds, like setters and pointers.

The first major competition was the tremendously popular 1908 All-Alaska Sweepstakes (AAS), which was started by Allan "Scotty" Alexander Allan, and ran 408 miles (657 km) from Nome to Candle and back. During its heyday, mushing was also a popular sport during the winter, when mining towns shut down. Dog sledding persisted in the rural parts of Alaska, but was almost driven into extinction by the spread of snowmobiles in the 1960s. Roadhouses where travelers could spend the night sprang up every 14 to 30 miles (23-48 km) until the end of the 1920s when the mail carriers were replaced by bush pilots flying small aircraft, and the roadhouses vanished.

The primary communication and transportation link to the rest of the world during the summer was the steamship; but between October and June the northern ports like Nome became icebound, and dog sleds delivered mail, firewood, mining equipment, gold ore, food, furs, priests, and other needed supplies between the trading posts and settlements across the Interior and along the western coast. Portions of the Iditarod Trail were used by the Native American Inuit and Athapaskans hundreds of years before the arrival of Russian fur traders in the 1800s, but the trail reached its peak between the late 1880s and the mid 1920s as miners arrived to dig coal then gold, especially after the Alaska gold rushes at Nome in 1898, and at the "Inland Empire" along the Kuskokwim Mountains between the Yukon and Kuskokwim rivers, in 1908.
. Many who are familiar with the history of the Iditarod look back with nostalgia on the early days, when the mushers had smaller teams with bigger dogs, and the emphasis was not on winning the race; the emphasis was on completing the task.

With the money, came the huge dog lots breeding the scrawny (but fast) dogs that we see today. Then came the money, specifically the money that accompanies network TV coverage. When it began, it wasn't so much a "race" as an "event" to commemorate the tradition of dog mushing, where serious mushers got together to test themselves and their dogs. When the Iditarod began (1973), it was much different from what it is today.

Despite vast improvements in dog care deaths still occur, and a small but vocal group of activists continue to speak out against the race. On the negative side, the death of more than a dozen dogs on the trail during the first race in 1973 was widely criticized by animal rights groups. Print and television journalists and crowds of spectators attend the start at the intersection of Fourth Avenue and D Street in Anchorage, and in smaller numbers at the checkpoints along the trail. The Iditarod became famous outside the state largely because of media attention directed at Libby Riddles, a longshot who became the first woman to win the race in 1985; and then at Susan Butcher, who became the second woman to win the race in 1986, and went on to dominate the race for half a decade.

While the yearly field of more than fifty mushers and about a thousand dogs is still largely Alaskan, competitors from fourteen countries have completed the event including the Norwegian Robert Sørlie, who became the first international winner in 2003.
The race is the most popular sporting event in the state, and the top mushers and their teams of dogs are treated as celebrities; this popularity is credited with the resurgence of recreational mushing in the state since the 1970s. . The race is also associated with the spirit of "America's Last Frontier", including the traits of perseverance, testing one's own limits, and an adventuresome spirit.

The Iditarod is regarded as a symbolic link to the early history of the state, and has many traditions commemorating the legacy of dog mushing, most famously the diphtheria serum run of 1925 which saved the children of Nome from the "black death". While the start in Anchorage is in the middle of a large urban center, most of the route passes through widely-separated towns and villages, and small Athapaskan and Inuit settlements. The teams cross a harsh but starkly beautiful landscape under the canopy of the Northern Lights, through tundra and spruce forests, over hills and mountain passes, and across rivers. state of Alaska, from the city of Anchorage in the southeast, up the Rainy Pass of the Alaska Range into the sparsely populated Interior, and then along the shore of the Bering Sea, finally reaching Nome in the northwest.

The trail runs through the U.S. The Iditarod Trail Sled Dog Race, usually called the "Iditarod" and known as the "Last Great Race", is an annual dog sled race in Alaska, where mushers and teams of dogs cover more than 1,000 miles (1,600 km) in less than two weeks, frequently through blizzards causing whiteout conditions, and sub-zero weather and gale-force winds which can cause the wind chill to reach −100° F (−75° C). Retrieved March 5, 2005. Southern route.

--. Retrieved March 5, 2005. Northern route. --.

Retrieved March 5, 2005. Champions. Iditarod Trail Committee, Inc. --.

Retrieved March 5, 2005. 2005 Iditarod Mushers. Iditarod Trail Committee, Inc (March 5, 2005). ISBN 0-88240-411-3.

(1991) Iditarod: The Great Race to Nome. Bill Sherwonit and Jeff Schultz. ISBN 0-8061-3103-9. America's National Historic Trails.

Cordes (1999). Kathleen A.