Tuesday, June 06, 2006

Woodstock ( Read it )

How Woodstock Happened ... Part 1

The last bedraggled fan sloshed out of Max Yasgur's muddy pasture more than 25 years ago. That's when the debate began about Woodstock's historical significance. True believers still call Woodstock the capstone of an era devoted to human advancement. Cynics say it was a fitting, ridiculous end to an era of naivete. Then there are those who say it was just a hell of a party.

The Woodstock Music and Art Fair in 1969 drew more than 450,000 people to a pasture in Sullivan County. For four days, the site became a countercultural mini-nation in which minds were open, drugs were all but legal and love was "free". The music began Friday afternoon at 5:07pm August 15 and continued until mid-morning Monday August 18. The festival closed the New York State Thruway and created one of the nation's worst traffic jams. It also inspired a slew of local and state laws to ensure that nothing like it would ever happen again.

Woodstock, like only a handful of historical events, has become part of the cultural lexicon. As Watergate is the codeword for a national crisis of confidence and Waterloo stands for ignominious defeat, Woodstock has become an instant adjective denoting youthful hedonism and 60's excess. "What we had here was a once-in-a-lifetime occurrence," said Bethel town historian Bert Feldman. "Dickens said it first: 'It was the best of times. It was the worst of times'. It's an amalgam that will never be reproduced again."

Gathered that weekend in 1969 were liars and lovers, prophets and profiteers. They made love, they made money and they made a little history. Arnold Skolnick, the artist who designed Woodstock's dove-and-guitar symbol, described it this way: "Something was tapped, a nerve, in this country. And everybody just came."

The counterculture's biggest bash - it ultimately cost more than $2.4 million - was sponsored by four very different, and very young, men: John Roberts, Joel Rosenman, Artie Kornfeld and Michael Lang. The oldest of the four was 26. John Roberts supplied the money. He was heir to a drugstore and toothpaste manufacturing fortune. He had a multimillion-dollar trust fund, a University of Pennsylvania degree and a lieutenant's commission in the Army. He had seen exactly one rock concert, by the Beach Boys.

Robert's slightly hipper friend, Joel Rosenman, the son of a prominent Long Island orthodontist, had just graduated from Yale Law School. In 1967, the mustachioed Rosenman, 24, was playing guitar for a lounge band in motels from Long Island to Las Vegas.

Roberts and Rosenman met on a golf course in the fall of 1966. By winter 1967, they shared an apartment and were trying to figure out what they ought to do with the rest of their lives. They had one idea: to create a screwball situation comedy for television, kind of like a male version of "I Love Lucy".

"It was an office comedy about two pals with more money than brains and a thirst for adventure." Rosenman said. "Every week they would get into a different business venture in some nutty scheme. And every week they would be rescued in the nick of time from their fate. "
To get plot ideas for their sitcom, Roberts and Rosenman put a classified ad in the Wall Street Journal and The New York Times in March 1968: "Young Men With Unlimited Capital looking for interesting, legitimate investment opportunities and business propositions. " They got thousands of replies, including one for biodegradable golf balls. Another seemed strange enough to work as a real business venture; Ski-bobs, bicycles on skis that were a fad in Europe. Roberts and Rosenman researched the idea before abandoning it. In the process, the two went from would-be television writers to wanna-be venture capitalists. "Somehow, we became the characters in our own show," Rosenman said.

Artie Kornfield, 25, wore a suit, but the lapels were a little wide and his hair brushed the top of his ears. He was a vice president at Capitol Records. He smoked hash in the office and was the company's connection with the rockers who were starting to sell millions of records. Kornfeld had written maybe 30 hit singles, among them "Dead Man's Curve," recorded by Jan and Dean. He also wrote songs and produced the music for the Cowsills.

Michael Lang didn't wear shoes very often. Friends described him as a cosmic pixie, with a head full of curly black hair that bounced to his shoulders. At 23, he owned what may have been the first head shop inthe state of Flordia. In 1968, Lang had produced one of the biggest rock shows ever, the two-day Miami Pop Festival, which drew 40,000 people. At 24, Lang was the manager of a rock group called Train, which he wanted to sign to a record deal. He bought his proposal to Kornfeld at Capitol Records in late December 1968.

Lang knew Kornfeld had grown up in Bensonhurst, Queens, like he had. Lang got an appointment by telling the record company's receptionist that he was "from the neighborhood." The two hit it off immediately. Not long after they met, Lang moved in with Kornfeld and his wife, Linda. The three had rambling, all-night conversations, fueled by a few joints, in their New York City apartment.

One of their ideas was for a cultural exposition/rock concert/extravaganza. Another was for a recording studio, to be tucked off in the woods more than 100 miles from Manhattan in a town called Woodstock. The location would reflect the back-to-the-land spirit of the counterculture. Besides, the Ulster County town had been an artists' mecca for a century. By the late 1960s, musicians like Bob Dylan, The Band, Tim Hardin, Van Morrison, Jimi Hendrix and Janis Joplin were moving to the area and wanted a state-of-the-art studio.

Lang and Kornfeld were searching for seed money for the festival and money to build the recording studio. They never saw the "young men with unlimited capital" ad, but their lawyer recommended they talk to Roberts and Rosenman. The four met in February 1969. "We met with them in their apartment on 83rd Street in a high-rise," Lang recalls. "They were kind of preppy. Today, I guess they'd be yuppies. They were wearing suits. Artie did most of the talking, because I think they seemed puzzled by me. They were curious about the counterculture, and they were somewhat interested in the project. They wanted a written proposal, which we had but we didn't bring with us. We told them that we would meet again with a budget for the festival.

To this day, the founders of Woodstock disagree on who came up with the original idea for the concert. And, dulled by time, competition and countess retelling, no one recollection is consistent. Lang and Kornfeld say Woodstock was always planned as the largest music festival ever held. At the second meeting, Lang recalls discussing a budget of $500,000 and attendance of 100,000. Lang said he had started looking at festival sites in the fall of 1968, which would have been well before he'd hooked up with Kornfeld or Roberts and Rosenman. But Rosenman and Roberts maintain that they were the driving force behind the festival. As Rosenman and Roberts recall it, Kornfeld and Lang primarily wanted a studio, hyped by a party for rock'n'roll critics and record company executives. "We would have cocktails and canapes in a tent or something," Rosenman said. "We'd send limos down to New York to pick everyone up. Tim Hardin or someone could sing. Maybe, if we were lucky, Joan Baez would get up and do a couple of songs."

At some point, Rosenman and Roberts focused on the party idea and decided that it really ought to be a rock concert. "We made a deal," Rosenman said. "We'd have the party, and the profits from the party would be used to pay for the recording studio. Ultimately, we had the money, so what we said went."

By the end of their third meeting, the little party up in Woodstock had snowballed into a bucolic concert for 50,000 people, the world's biggest rock'n'roll show. The four partners formed a corporation in March. Each held 25 percent. The company was called Woodstock Ventures, Inc., after the hip little Ulster County town where Dylan lived.

The Woodstock Ventures team scurried to find a site. Real estate agents across the mid-Hudson were scouring the countryside for land to rent for just a few months. Feelers went out in Rockland County, then in Orange. For $10,000, Woodstock Ventures had leased a tract of land in the Town of Wallkill owned by Howard Mills, Jr. "It was a Sunday in late March," Rosenman said. "We drove up to Wallkill and saw the industrial park. We talked to Howard Mills and we made a deal." "The vibes weren't right there. It was an industrial park," Roberts interjected. "I just said, 'We gotta have a site now.'"

The 300-acre Mills Industrial Park offered perfect access. It was less than a mile from Route 17, which hooked into the New York State Thruway, and it was right off Route 211, a major local thoroughfare. It has the essentials, electricity and water lines.

The land was zoned for industry; among the permitted uses were cultural exhibitions and concerts. The promoters approached the town planning board and were given a verbal go-ahead because of the zoning. Nonetheless, Lang was unhappy with the site. It was missing the back-to-the-land ambience Woodstock Ventures was selling. "I hated Wallkill," Lang said. Ventures set to work on the Mills property, all the while searching for an alternative.

Rosenman told Wallkill officials in late March or early April that the concert would feature Jazz bands and folk singers. He also said that 50,000 people would attend if they were lucky. Town Supervisor Jack Schlosser throught something was fishy. "More than anything else, I really feel they were deliberately misleading the town," Schlosser said. "The point is, they were less than truthful about the numbers. I became more and more aware, as discussions with them progressed, they did not really know what they were doing. I was in the Army when divisions were 40,000 or 50,000 men," he said. "Christ almighty, the logistics involved in moving men around... I said at one point, 'I don't care if was a convention of 50,000 ministers," I would have felt the same way."

In the cultural-political atmosphere of 1969, promoters Kornfeld and Lang knew it was important to pitch Woodstock in a way that would appeal to their peer's sense of independence. Lang wanted to call the festival an "Aquarian Exposition," capitalizing on the zodiacal reference from the musical "Hair". He had an ornate poster designed, featuring the water-bearer.

By early April, the promoters were carefully cultivating the Woodstock image in the underground press, in publications like the Village Voice and Rolling Stone magazine. Ads began to run in The New York Times and The Times Herald-Record in May. For Kornfeld, Woodstock wasn't a matter of building stages, signing acts or even selling tickets. For him, the festival was always a state of mind, a happening that would exemplify the generation. The event's publicity shrewdly appropriated the counterculture's symbols and catch phrases. "The cool PR image was intentional, "he said.

The group settled on the concrete slogan of "Three Days of Peace and Music" and downplayed the highly conceptual theme of Aquarius. The promoters figured "peace" would link the anti-war sentiment to the rock concert. They also wanted to avoid any violence and figured that a slogan with "peace" in it would help keep order.

The Woodstock dove is really a catbird; originally, it perched on a flute. "I was staying on Shelter Island off Long Island, and I was drawing catbirds all the time," said artist Arnold Skolnick. "As soon as Ira Arnold (a copywriter on the project) called with the copy-approved 'Three Days of Peace and Music,' I just took the razor blade and cut that catbird out of the sketchpad I was using. "First, it sat on a flute. I was listening to jazz at the time, and I guess that's why. But anyway, it sat on a flute for a day, and I finally ended up putting it on a guitar."
Melanie Safka had a song on the radio called "Beautiful People. "An extremely hip DJ named Roscoe on WNEW-FM played it. One day, Melanie ran into a curly-haired music-business guy named Michael Lang, who was talking about a festival he was producing. When Melanie asked if she could play there, Lang's answer was a very laid-back, "Sure." "I thought it would be very low key," recalled Melanie.

Woodstock Ventures was trying to book the biggest rock'n'roll bands in America, but the rockers were reluctant to sign with an untested outfit that might be unable to deliver. "To get the contracts, we had to have the credibility, and to get the credibility, we had to have the contracts, "Rosenman said. Ventures solved the problem by promising paychecks unheard of in 1969. The big breakthrough came with the signing of the top psychedelic band of the day, The Jefferson Airplane, for the incredible sum of $12,000. The Airplane usually took gigs for $5,000 to $6,000. Creedence Clearwater Revival signed for $11,500. The Who then came in for $12,500. The rest of the acts started to fall in line. In all, Ventures spent $180,000 on talent. "I made a decision that we needed three major acts, and I told them I didn't care what it cost," Lang said. "If they had been asking $5,000, I'd say, 'Pay 'em $10,000.' So we paid the deposits, signed the contracts, and that was it: instant credibility."In the spring of 1969, John Sebastian's career was on hold. From 1965 to 1967, Sebastian's band, the Lovin' Spoonful, had cranked out hit after hit - "Do You Believe in Magic," "You Didn't Have To Be So Nice," "Did You Ever Have To Make Up Your Mind," "(What a Day For a) Daydream" and "Summer In The City." But in 1967, after the Lovin' Spoonful appeared on "The Ed Sullivan Show", things began to go wrong. Two band members were busted for pot possession and left the group. Their replacements never quite fit in. In 1968, the group broke up, and Sebastian tried going solo. But his performing career wasn't taking off. So, in the spring of 1969, Sebastian headed west to do a little soul searching. He ended up at a California commune where the hippies made money by making brightly colored shirts and jackets by a process they called tie-dye.

The residents of Wallkill had heard of hippies, drugs and rock concerts, and after the Woodstock advertising hit The New York Times, The Times Herald-Record and the radio stations, local residents knew that a three-day rock show, maybe the biggest ever, was coming. Besides, Woodstock Venture's employees sure looked like hippies. In the minds of many people, long hair and shabby clothes were associated with left-wing politics and drug use. The new ideas about re-ordering society were threatening to many people. In Wallkill, those feelings were unleashed upon Mills and his family. Residents would stop Mills at church to complain. Ventures tried to head off some of the complaints by hiring Wes Pomeroy, a former top assistant at the Justice Department, to head the security detail. A minister, the Rev. Donald Ganoung, was put on the payroll to head up local relations.

Allan Markoff watched the two freaks walk into his store in late April or early May. They were Lang and his buddy, Stan Goldstein. Goldstein, 35, had been one of the organizers of the 1968 Miami Pop Festival. For Woodstock, he was coordinator of campgrounds. "They wanted me to design a sound system for 50,000 or so people," said Markoff, who owned the only stereo store in Middletown, the Audio Center on North Street. "They said there could even be 100,000, might even go to 150,000."

He thought Lang and Goldstein were nuts. "There had never been a concert with 50,000; that was unbelievable," Markoff said. "Now, 100,000, that was impossible. It's tantamount to doing a sound system for 30 million people today." Markoff, then 24, was the only local resident listed in the Audio Engineering Society Magazine. Lang and Goldstein had picked his name out of the magazine; suddenly, Markoff was responsible for gathering sound gear for the greatest show on earth. He remembers one characteristic of the sound system. At the amplifier's lowest setting, the Woodstock speakers would cause pain for anyone standing within 10 feet.

Markoff had doubts about the sanity of the venture until he saw the promoters' office in a barn on the Mills' land. "That's when I saw all these people on these phones, with a switchboard," Markoff said. "When I saw that, I said, 'Hey, this could really happen.'"

Rosenman and Roberts couldn't entice any of the big movie studios into filming their weekend upstate. So they got Michael Wadleigh. Before Woodstock, rock documentation meant obscurity and few profits. A year before Woodstock, Monterey Pop had fizzled at the box office, making movie execs skittish over the idea of funding another rock film. During the summer of Woodstock, Wadleigh, 27, was gaining a reputation as a solid cameraman and director of independent films. Two years earlier, he had dropped out of Columbia University of Physicians and Surgeons, where he was studying to be a neurologist. Since then, he'd spent his time filming on the urban streets, the main battlefield for the cultural skirmishes of the 1960s. He'd filmed Martin Luther King Jr. He'd filmed Bobby Kennedy and George McGovern talking to middle Americans on the campaign trail in '68.

Wadleigh was experimenting with using rock'n'roll in his films as an adjunct to the day's social and political themes. He was also working with multiple images to make documentaries more entertaining than those featuring a bunch of talking heads. And then the Woodstock boys came to his door. Their idea was irresistable. The money was not. Wadleigh went for it anyway.

Goldstein went alone to his first town board meeting in Wallkill. "This was before we knew we had problems," he said. "It was probably in June. We had a full house. No more than 150 people. There were some accusations. Someone made some references to the Chicago convention. That it was young people, and this is the way the youth reacted, and that's what we could expect in our community. (Wallkill Supervisor Jack) Schlosser said that Mayor Daley knew how to handle that. Then I lost my temper. I said there was no need for the violence and that (the police) reaction caused the violence. I said that Daley ran one of the most corrupt political machines in history."

Schlosser, who attended the Chicago convention, didn't recall such a specific exchange about Daley. He did remember the convention, however "I saw these people throw golf clubs with nails in them," he said of the Chicago protesters. "I saw them throw excretion. The police, while I was there at least, showed remarkable restraint."

As the town meetings and the weeks wore on, the confrontation between Ventures and the residents of Wallkill got worse. Woodstock's landlord, Howard Mills, was getting anonymous phone calls. The police were called, but the culprits never were identified, much less caught. "They threatened to blow up his house," Goldstein said. "There were red faces and tempers flaring. People driven by fear to very strange things. They raise their voices and say stupid things they would never ordinarily say. "To this day, Howard Mills will not discuss how his neighbors turned against him in 1969. "I know that it is a part of history, but I don't want to bother about it," Mills said.

Friday, June 02, 2006

Chaos Rules..

About Chaos --

In the 17th and 18th centuries, Newtonian mechanics was triumphant in its explanation of the solar system. In fact, many theologians at that time pictured God as a great clockmaker, who had only to start the universe and then step back and let Newton’s laws determine the future. But does everything in the universe run like a fine clock? The nineteenth century mathematician Poincaré found an exception—the motion of three mutually interacting astronomical objects. When the three objects have comparable mass, as suggested in the drawing, the motion of each body produces a substantial change in the gravitational field experienced by the other two, thereby making a solution impossible.

The only way to tackle this kind of problem is by a series of iterations—calculate the gravitational forces, let the objects move for a short time under these forces, then recalculate the forces based on the objects’ new positions, etc. Even without a computer, Poincaré could see that the resulting orbits were aperiodic and wildly disordered. Moreover he discovered that a small change in the initial conditions—the initial positions and velocities of the three objects—produced a huge change in the orbits. This important observation was to lie fallow for eighty years, awaiting the development of chaos theory.
Step outside and behold a chaotic system—the weather. Although there are short-term patterns, the system never repeats, and long-range forecasting remains an unsolved problem. Back in the 1960s, meteorologist Ed Lorenz build a simple computer weather model that, when given some initial values, chugged out numbers that corresponded to wind speed, precipitation, and temperature. Then this output went back in as the new input, and the model generated simple predictions over time.

Desiring to repeat a particular computer run, Lorenz restarted the computer but rounded down the initial values from six significant figures to three. Since temperatures weren’t measured to three significant figures of accuracy anyway, this approximation should have had no effect. And indeed, the output of the new run at first followed that of the old, but slowly and steadily the two diverged, as shown in the first graph, until the results were completely different and continued so, as shown in the graph. Lorenz was stunned—a change in input too small to correspond to a measurable difference had totally altered the output. Lorenz’ result exemplifies “exquisite sensitivity to initial conditions,” otherwise known as the butterfly effect—the beat of a butterfly’s wing in China could, in principle, change the weather in New York .

This image is a phase space graph for a pendulum with friction. Each point corresponds to a state of particular position and momentum, and the succession of points around the curve correspond to the evolution of the system with time. As friction erodes the amplitude and speed of the bob, the phase space plot spirals in to the equilibrium position and zero momentum (zero speed)
Lorenz presented his simulation results with a graph of what physicists call “phase space.” In this space, each axis of the graph corresponds to a system variable, such as the position and momentum of a particle, so the entire state of the system can be expressed by the point in phase space it occupies at a certain time. A pendulum with friction would have a phase space diagram like that shown in the second graph, a spiral that winds in to a point, as energy dissipates and the pendulum amplitude and speed progressively decrease. For more on the phase space of a pendulum, see the first link.

The Lorenz attractor, displaying the order present in a chaotic system. The graph never crosses itself, so the system never repeats its state. (image courtesy of Glenn Elert)

When Lorenz drew a phase space plot for his weather simulation, the results were quite different, as shown in the third graph, where the curve continues indefinitely without repeating itself and winds around and around the two points. This graph, dubbed the “strange attractor,” eventually became a potent symbol for the young field of chaos research.
Many systems show chaotic behavior. To name just a few—

  • animal populations
  • the red spot of Jupiter
  • electrical signals in the human heart
  • convection

Ecology can lead to chaos. In describing population dynamics, one of the key variables is the rate of growth, which is related to the animal’s fertility. As this rate increases, the equilibrium population at first goes up. But with further increase, the population alternates between two different values, as shown in the first graph. In fact, such seemingly implausible behavior had been observed, but ecologists assumed that there was an equilibrium in between the alternating populations, obscured by some ecological complication .

An animal population plotted vs time. The population gyrates between two values, so there is no equilibrium.
In the 1970s, the biologist Robert May, who began as a theoretical physicist, made a thorough study of the simple quadratic equation .
xn+1 = rxn(xn – 1)
Here xn is equal to the population in the n th generation, and it has been scaled to a maximum value of one for convenience. This equation describes how a population changes from the nth generation to the (n+1)th. In other words, the population in each generation is a function of the population in the previous generation. The symbol “r” is the rate of growth. The factor (xn – 1) expresses the effects on a large population of limited food supply or overcrowding—in this simple model, when the population reaches one, all the organisms die.

May investigated the effect of the rate of growth. At first, increasing this rate likewise increased the equilibrium population, as expected (see the second graph). But with further increase in growth rate, the curve splits, and the population has two values, which alternate, so there is no equilibrium. This case corresponds to the first graph above. As fertility increases further, the curve splits again, until it finally enters regions of chaotic behavior. The above equation had been around since the 1950s, yet biologists had been unable to recognize this prediction. They looked only for equilibrium, so they missed chaos.

The classic period-doubling graph, a hallmark of chaos. This particular graph shows the dependence of an animal population on its rate of growth. At a certain value of the rate, there is no equilibrium population, and the number gyrates between two values, as in the first graph on this page. This process of “bifurcation” continues, and the population then dissolves into chaos (the black region).
A surprising and compelling example of chaos turned out to be a familiar system that had never been investigated—the dripping faucet. Robert Shaw, a physics grad student in the 1970s, decided to investigate the faucet’s flow by timing the dripping. When the water flow is low, the result is a steady dripping that increases its rate as the faucet is turned. As the system is driven harder by increasing the flow, the constant interval between drops gives way to two alternating intervals (e.g., successive drips separated by .3 sec, .1 sec, .3 sec, .l sec), just as with May’s mathematical description of animal populations. Then, at higher flow rates, each of the two different intervals itself subdivides; a still higher rate provokes chaotic behavior, with no discernable pattern. The appearance of chaos in this everyday system, and the precise analysis of the time series, made a deep impression on many physicists.
Chaos became an accepted field of physics research only in the 1980s. Before then, physics journal editors were reluctant to publish chaos papers, so the early workers had to struggle for professional recognition. To many physicists, the emergence of chaos into the physics mainstream, and the overthrow of part of Newtonian determinism, have been nothing short of revolutionary. Chaos is studied actively, and you can read more about it in future Physics in Actions.

A different view of a Lorenz attractor (image courtesy of Paul Bourke, Centre for Astrophysics and Supercomputing, Swinburne University)

Sonic Shock

Shock waves from an F-18 in supersonic flight. (image courtesy of NASA).
Have you ever heard a sonic boom? Have you ever seen the shock waves that cause one? The first image shows shock waves from an F-18—a Navy jet—moving at supersonic speed. Shockwaves are regions of increased air pressure and temperature, and when these waves reach the ground, we hear the sonic boom. For another example, look at the “shadowgram” image of the speeding bullet. Here the first shock wave is curved and is actually slightly ahead of the bullet (it’s “detached”), and other shocks emanate from the bullet itself and even from the turbulent region of disturbed air directly behind.

A bullet moving faster than the speed of sound. In this kind of image, called a shadowgraph, the air within the shock waves, which has a different density from the surrounding air, bends light passing through to cast shadows on a screen (image courtesy of Andrew Davidhazy, Rochester Institute of Technology).

To understand these shock waves, take a look at the diagrams below, which show waves spreading out from an object moving through a fluid. Such waves are produced continually as the object moves. Each diagram shows a series snapshots taken at regular time intervals. These waves spread out in circles, like ripples from a stone dropped into a pond, and move at the speed of the waves in the fluid. Notice that if the object moves faster than the speed of the waves, the circles form a “V”-shaped wake, like the wake of a ship or the shock waves from the nose of the F-18 in the image above

Blunt nose of the Space Shuttle (image courtesy of NASA)

Unlike the needle-nosed Bell X-1, spacecraft reentry vehicles are blunt, like the nose of the Space Shuttle, shown in the photo. To understand how this design evolved, look at the shadowgrams of shock waves from various models of the reentry capsule for the first US manned spacecraft, Mercury, which first reached Earth orbit in 1962. Comparing the first image to the others shows that the shock wave detaches from a blunt body.

These shadowgraphs show shock waves from a series of models for the project Mercury reentry vehicle. Note how the rounded shapes detach the shock wave. (images courtesy of NASA) {TOP}

One of the two XB-70 bomber prototypes. The dark lines under the wings, near the wingtips, indicate the places where the wingtips fold down so the aircraft assumes an efficient shape for riding its shock wave. (image courtesy of NASA)
In the manned capsule concept, the larger radius of curvature—that is, the more smoothly rounded nose—reduces the rate of heat transfer from the hot shock wave to the vehicle surface, so the capsule can survive the fierce heating of reentry. Also, the blunt shape increases air resistance, slowing the reentering capsule at higher altitudes, where the lower air density produces a correspondingly lower rate of heating.

A blunt body is not, however, the only possible way to get back from space. A quite different approach, called “Waverider,” is basically a sharp-edged flying delta wing, conceived in Scotland in the 1950s. Gliding at several times the speed of sound, this vehicle would ride on its own shock wave, which would provide high lift with low drag. The Air Force XB-70 (see photo) was the first Waverider, but only two were built, and one of these crashed. This aircraft had wing tips that folded down to capture the shockwave underneath the wing and provide additional lift. A more recent Waverider prototype is a joint NASA-US Air Force project, LoFLYTE, an eight-foot-long, computer-controlled prototype (see photo Top ).

This photo shows the eight-foot-long prototype LoFLYTE, a test vehicle for the Waverider concept. LoFLYTE, which first flew in 1997, has a wing designed to ride on top of its own shockwave. (photo courtesy of ASTRA, www.astra.org.uk which can be reached at info@astra.org.uk)

The study of shock waves provides valuable information about the fundamental physics of fluids and also leads to important applications in the design of spacecraft and aircraft. Many physicists work on fluids, both in private industry and in departments of physics and aerospace/mechanical engineering in universities.

Worm Hole...

Worm hole Thu ề @ 10:02 am

Worm hole is an interesting thought, and concept. Physicists tried to describe it mathematically by constructing a topological model. Everyone like the result of wormhole, especially, intra-universe worm hole which can bring you from one point to another point in the universe. As far as inter-universe wormhole is concerned, there are ideas showing that you just can see the light of another universe, and the price is exchanging your life for seeing that. Anyway, I am afraid of that there is no real phenonmenon that satisfied the mathematical model of worm-hole, since it affects spacetime too much. (Source:wikipedia)As for a sake of simple illustration, I will packet the result for you as following
First, believe that our universe is not flat. So it is arguably to claim that wormhole is physically existed.
Second, as far as physics has gone, also as far as what I read and learnt :-), I believed in Big Bang’s prediction of the size and the age of the universe. That is to say our universe is very huge, but it does have a boundary and an end, since the universe is expanding from a singularity and have its own age.
Third, if there are other universes, then the distance between any 2 universes is not space distance, but spacetime distance, therefore, it is hard to claim to bring you to other universe. For example, the distance between the earth and the moon is space distance, and universes are spacetime separated, which I think our topological model is hard to illustrate.
Fourth, it is theoretically to propose that a wormhole can help particle to escape the black hole, assumed that the particle falled inside the event horizon.

Antartica ( About Grace )

Remote and beautiful, Antarctica is covered by an ice sheet averaging several kilometers in thickness that locks up some 70% of Earth’s fresh water—if it all melted, the oceans would rise about 70 m. Melting of the ice sheet is an obvious concern, since temperatures in the polar regions are increasing at about two-and-a-half times the average rate for Earth. Nevertheless, as recently as 2004, substantial melting of the ice sheet had been dismissed because Antarctica is so cold. Except in the Antarctic Peninsula (which extends north in the direction of South America—see map), the average temperature on the continent is -7° C, and at no time in the year does the temperature rise above zero C, so no melting would occur. In the Antarctic Peninsula (see radar map), the average temperatures can reach -5°, and melting is possible during the two warmest months of the year. Given these low temperatures, only the huge floating ice shelves that extend out from the coast would be threatened by ocean warming, since their undersides are in contact with ocean water. But melting of the shelves (see photo) would not raise sea level, because floating ice displaces its weight, which does not change upon melting. Still, the shelves are believed to play a role in preventing the movement of the rest of the ice sheet towards the ocean, and it is at the coast, where the underside of the shelves ride on ocean water, that a global temperature rise could produce increased melting.

The thickness of Antarctic ice has been measured by satellite-bourne radar. A pulsed radar beam is bounced off the ice, and the travel time from satellite to the surface and back is precisely measured. This method, though, has the disadvantage that the radar beam sweeps only a small area of land in each pass. Moreover, it is difficult to obtain results from regions where the height of the ice changes in the area swept by the radar, typically 15 km or more in diameter. The height of the ice sheet tends to be especially variable near the coast, where melting ice shelves have their largest impact. A very different approach to measuring ice sheet thickness comes from the study of Earth’s gravity. If some of the sheet melts, the thickness of the sheet decreases and so does the acceleration of gravity over it, slightly changing the orbit of a satellite that passes overhead. A satellite in a circular orbit over a region of reduced mass would experience a decreased acceleration of gravity, increase its altitude (since the lower acceleration of gravity would not be sufficient to maintain the circular orbit) and slow down. Once clear of the area of lower gravity, the satellite would speed back up.

This orbital effect is utilized in the Gravity Recovery and Climate Experiment (GRACE), a joint venture among NASA, the Jet Propulsion Lab (JPL), and the German space agency DLR. GRACE employs two identical satellites flying in formation in the same polar orbit (see drawing) at a separation of 219 km (137 mi). As the pair flies over Antarctica, the first satellite slows down, due to the melting of the ice sheet, so the separation between the two decreases. Later, when both have cleared the continent, the separation returns to its prior value. Since all Antarctic ice contributes to the gravity that the satellites experience, GRACE determines the thickness of the entire ice sheet, as opposed to the limited coverage of the radar studies.

Antartica ( GRACE Project )

The two GRACE satellites flying in formation and communicating by a microwave beam, which is shown as a blue line; (image courtesy of NASA)

To precisely measure the separation between the two GRACE satellites, each one sends out a microwave signal, which the other detects, as shown in the drawing. On-board instrumentation measures the time of transmission and relative phase of the generated and received microwave signals. In addition, the global positioning system accurately specifies the satellites’ positions in three dimensions to within a few centimeters.

Since the measured change in gravity is so small, there are many corrections. The atmosphere beneath the satellites has mass and therefore exerts a small gravitational force. This effect can be modeled and accounted for using global air pressure data. Also, they are subject to non-gravitational forces, such as atmospheric drag, the pressure of sunlight, and even the pressure of reflected sunlight from Earth. Accelerometers on each satellite detect the effects of these forces, and a star-tracker determines the attitude of the spacecraft so that atmospheric drag can be determined.
When these data are combined, the separation of the pair of satellites can be specified to within a micron, about 1/50 the diameter of a human hair. Since the satellites fly in and out of sunlight, thermal expansion must be minimized, so their frames are constructed of plastic reinforced with carbon fiber.

Iceberg formed when a part of the ice shelf broke off. The shelves are believed to play a role in preventing the movement of the rest of the ice sheet towards the ocean. (photo by Robert Reeves © Commonwealth of Australia)

A big complication in the GRACE measurement of the Antarctic ice sheet thickness is the fact that the land beneath is lifting, part of the “post-glacial rebound” after the last Ice Age, which ended only about 10,000 years ago (melting in Antarctica continued up until only about 4,000 years ago). The crust—the uppermost layer of Earth—floats on the rock beneath, which is plastic and responds to changes in its “load” (see last link). The melting of the huge ice age glaciers removed a large mass from Antarctica, and the continent is slowly lifting to reestablish equilibrium. The GRACE scientific team used geological estimates of ice thickness changes and a model of rock flow beneath Earth’s surface to estimate the uplifting of the land, which is a significant effect.
After taking into account all the above effects, the GRACE scientists find that from 2002 through 2005, the volume of the Antarctic ice sheet decreased substantially, corresponding to .4 mm plus or minus .2 mm of sea-level increase per year. This result was a surprise, both because of the extremely low temperatures in Antarctica, as mentioned above, and because forecasts of global warming had predicted increased snowfall in Antarctica.

In an earlier study, GRACE determined that the Greenland ice sheet is melting more rapidly than previously thought—in fact, the melting in Greenland and in Antarctica each produce about the same rate of sea level rise. So these ice sheets together add about .8 mm/yr. The overall rate of sea level rise over the last ten years, as obtained from statistical studies of radar measurements, is about 3 mm/year, and roughly half of this increase is due to thermal expansion of the oceans.
As the GRACE project continues, more data will accumulate and delineate the trend in ice sheet thickness over a longer time interval. Also, any change in the rate of melting would be unaffected by the correction for post-glacial rebound, which is presumed to be constant over long periods of time.
A meltstream in high summer on the Greenland ice sheet, (photo by Roger J. Braithwaite, The University of Manchester)