Tuesday, March 23, 2010
Some things you will read about: Light year; the distance that light travels in one year. Neutron star; a dead star whose atoms have been squeezed into a very dense fluid. Supernova; an explosion in which a star suddenly flares to many times its former brightness. We do know that black holes exist. However, we can only speculate about their exact composition and function.
Every person aboard is a thorough professional who has spent years in training for this mission. So far everything has gone exactly according to plan. Yet, as we approach our target, the black hole Entram X-14, profound anxiety is felt in every corner of the starship. We know that the gravity of Entram X-14 will suck us down, down into its depths, where no human has ever been before. We know we may be trapped forever in a place where time, or even death, does not exist. Or, if all goes well, we may totally disappear from our universe, to emerge from the other end of the black hole in some other alien universe.
Terms such as "stars hip," "black hole," and "alien universe" place us squarely in the pages of a science fiction novel or the latest space movie. Or do they? The fact is that serious astronomers have come up with theories just as fantastic as anything in the movies.
Stars can be described as huge hydrogen bombs in a state of continuous explosion. Each may consume billions of tons of hydrogen per second, yet continue to shine for billions of years. There must come a time, however, for every star when its hydrogen runs out. Setting out to analyze what happens then, scientists have concluded that stars do not all die the same way.
Most of the stars in our universe will die slowly in definite, dramatic stages.
As the hydrogen reaches a certain level, the star first expands to become a "red giant." Ages later, it pulls together again, shrinking down to a "white dwarf." Our sun, billions of years from now, will expand as a red giant, beyond the orbits of Mercury and Venus, then shrink to a white dwarf no larger than its own planets.
Finally, the very last of the hydrogen gone, the dead star will become a "black dwarf": a small, cold object in the vast void of space.
As old as our universe is, it is not yet old enough to contain any black dwarf stars, but enough red giants and white dwarfs have been studied to confirm the theory. All matter is made up of atoms, which are in turn made up of even smaller particles. Because they are microscopic in size, we seldom realize that atoms, like the universe itself, consist mainly of empty space. The parts of the atom move about in a void which is, by comparison, huge. In the formation of a white dwarf, these particles are simply squeezed more tightly together than they were before.
Some stars are many times larger than our sun. The intense heat at the center of such a star causes a rapid and tremendous explosion, a supernova. In one day, a star becoming a supernova will increase to billions of times its former brightness. Then it contracts with fierce speed, smashing its atoms to a kind of soup.
The result is a neutron star, enormously heavy for its small size and difficult to detect by telescope. Some years after this theory was worked out, advanced equipment picked up signals which exactly matched those that had been predicted. So, scientists were able to confirm the existence of neutron stars.
The very largest stars presented still another problem. The laws of science suggested that once these most massive stars began to pull inward, they wouldn't be able to stop at the white dwarf or neutron star stage. In fact, they might not be able to stop at all. The profound pull of gravity on so large an object contracting with such force should cause that object to continue collapsing forever. Such a situation goes beyond the edge of human experience. We cannot imagine an object which has no surface at all, but which contains all the mass and gravity of a giant star. We cannot really picture in our minds this black hole in space.
The gravity of a black hole would be so powerful that nothing which came near could elude it. The more matter it sucked in, the stronger it would grow, so that it could, in time, "devour" neighboring stars or groups of stars. At the very end, the entire universe could consist of one eternal black hole. One theory holds that this has already happened, and that our whole universe is really inside a giant black hole!
Nothing can escape from the gravity of a black hole, not even light. So, having put forth the probability that such things exist, astronomers were not going to be able to find one by ordinary means. The black hole would allow no signal of any kind to escape. On the other hand, matter in the act of being pulled in, should give out a last frantic burst of X-ray before disappearing. On this fact, scientists based their hopes of identifying an actual black hole in space.
Certain strange sources of X-ray have already been discovered. One in particular, Cygnus X-I (pronounced Sig-nus,) seemed promising, but more facts were needed to confirm the belief that it was a black hole. Those facts finally arrived in 1971 via the X-ray detecting satellite, Uhuru, launched from the African nation of Kenya two years before. Once scientists were able to analyze Uhuru's findings, they knew that Cygnus X-I was, in fact, a black hole in space.
In 1978, a second black hole, Scorpii V -861 (pronounced Scorpi,) was identified. There is a strong probability that many others will be added to the list as new and better methods of finding them are developed. Hard facts about black holes elude us almost as successfully as black holes themselves, and scientific reasoning leads us to theories stranger than any we could imagine. Physical laws worked out by Einstein and others prove that gravity has an effect on time and space. Taken to its absolute limit, in the center of a black hole, total gravity would cause time and space to cease existing. The laws of science, as we know them, would no longer apply.
Having accepted that, we open the door to all kinds of speculation. We know that everything in its vicinity is sucked into a black hole, and nothing ever comes out. That matter disappears forever. But where does it go? Nothing comes out of a black hole, at least not the same way it went in. Some scientists suggest, though, that there may be an exit after all, at the other end. Matter may pass through a black hole and come out somewhere else, light-years away. Or it may come out in a completely different universe. In fact, there may be billions of universes at the far ends of our black holes.
Since time actually ceases to exist in them, black holes could also act as time tunnels. It might be possible to travel through them into the distant past or future. Entering a black hole, matter will collapse into a state beyond our understanding. Emerging, though, it could simply expand again to normal size and shape to find itself in another time, another place. Scientists have other dreams as well. Huge amounts of energy are released by every object pulled into a black hole. If we could harness a small black hole and put it into orbit around the Earth, we could feed it anything at all, and the result would always be energy. Catching one, of course, would be a difficult trick. But where black holes are concerned, it may be that nothing is really impossible.
1. A black hole is a _____
2. If an extremely large and nearby star burned out tomorrow, the earth _____
3. According to the selection, which of the following is not a characteristic of a black hole?
4. Stars ______
5. Atoms are mostly made up of _____
6. Once you are inside a black hole, ________
7. Ages after a star shrinks to a white dwarf, it ________
8. Scientists are able to locate black holes in space by using ______
9. Another name for this selection could be _______
10.This selection is mainly about _______
A very good explanation of Black Holes by Stephen Hawking. He makes it very clear and easy to understand.
A Youtube Video: Mysteries of Deep Space: Black Holes.
For more on this subject, read "A Planetarium is a Theater".
Sunday, March 14, 2010
This is Bob Doughty.
And this is Phoebe Zimmermann with the VOA Special English program EXPLORATIONS. Today we tell the second part of our story about the discovery of gold in the area of Canada called the Yukon.
We tell about the thousands of people who traveled to Alaska and on to Canada hoping that they would become rich.
Last week, we told how three men discovered huge amounts of gold near the Yukon River in northwestern Canada. Their discovery started a rush of people traveling to the American territory of Alaska and across the border to Canada. History experts believe that between twenty and thirty thousand people traveled to the area.
Newspapers printed stories that said it was easy to become rich. All you had to do was pick up the gold from the ground. Books and magazines told how to travel to the area and the best method of finding gold. However, most of this information was false. It was not easy to find gold. It was extremely hard work under very difficult conditions.
The first ship carrying the gold seekers arrived in the port town of Skagway, Alaska, on July twenty-sixth, eighteen ninety-seven. These people were very lucky. It was summer and the weather was warm. However, they found few places to live in Skagway. Most people had to make temporary houses out of cloth.
Skagway was a very small port town. It had very few stores. And everything was very costly.
Skagway also had a crime problem. One of the chief criminals was a man named Jefferson Randolph Smith. He was better known as "Soapy" Smith. He did his best to take money from men who were on their way to seek gold.
One method he used seems funny, now. Soapy Smith had signs printed that said a person could send a telegram for five dollars. Many people paid the money to send telegrams to their families back home to say they had arrived safely in Skagway.
But they did not know that the telegraph office wires only went into the nearby forest. It was not a real telegraph office. It was a lie Soapy Smith used to take money from people who passed through Skagway.
Most of the gold seekers wanted to quickly travel to the area where gold had been discovered. However, the Canadian government required that each person had to bring enough supplies to last for one year if they wanted to cross the border into Canada. This was about nine hundred kilograms of supplies.
Each person had to bring food, tools, clothing, and everything else needed for one year. There were no stores in the Yukon. There was no place to buy food.
People who brought their supplies with them on the ship were lucky. Others had to buy their supplies in Skagway. They had to pay extremely high prices for everything they needed.
When they had gathered all the supplies, the gold seekers then faced the extremely hard trip into Canada. Their first problem was crossing over a huge mountain. They could cross the mountain in one of two places -- the White Pass and the Chilkoot Pass. Each gold seeker began by moving his supplies to the bottom of the mountain. Their progress to the mountain was painfully slow.
A man named Fred Dewey wrote to friends back home that it took him two weeks just to move his supplies from Skagway to the mountain. His wrote that his body hurt because of the extremely hard work.
Then the gold seekers had to move their supplies up the mountain.
Some men made as many as thirty trips before they had all of their supplies at the top. But others looked at the mountain and gave up. They sold their supplies and went back to Skagway.
At the top of the mountain was the United States border with Canada. Canadian officials weighed the supplies of each man. If the supplies did not weigh enough, the men were sent back. They were not permitted to cross into Canada.
A gold seeker who had successfully traveled up the mountain still faced the most difficult and dangerous part of the trip. Both trails up the mountain ended near Lake Bennett in British Columbia. From there it was almost nine hundred kilometers by boat down the Yukon River to the town of Dawson where gold had been discovered.
But there was no boat service. Each person or small group had to build their own boat. They cut down many trees to build the boats. Within a few months, some forests in the area were gone.
The summer quickly passed and winter began. The gold seekers were still building their boats. The Yukon River turned to ice. Winter in this area was extremely cold. The temperature often dropped to sixty degrees below zero Celsius. The cold could kill an unprotected person in just a few minutes.
American writer Jack London was among the gold seekers. He became famous for writing about his experiences in Alaska and Canada. He wrote a short story that perhaps best explains the terrible conditions gold seekers faced. It is called "The White Silence."
In the story, Mister London explained how the extreme cold made the world seem dead. It caused strange thoughts. He said the cold and silence of this frozen world seemed to increase a man's fear of death. This cruel cold could make a man afraid of his own voice.
The story also tells what could happen to a person who had an accident. There were not many doctors in the gold fields. A seriously injured person could only expect to die. Jack London's many stories truthfully explained just how hard it was to be a gold seeker in eighteen ninety-seven.
By the end of winter, the area around Lake Bennett was a huge temporary town of more than ten thousand people. They were all waiting for the ice to melt so they could continue on to the gold fields. On May twenty-eighth, eighteen ninety-eight, the Yukon River could again hold boats. The ice was melting. That day, more than seven thousand boats began the trip to Dawson.
Many of these gold seekers did not survive the trip on the Yukon River. All of the boats had to pass through an area called the White Horse Rapids. The water there was fast and dangerous. Many boats turned over. Many of the gold seekers died.
At last, the remaining gold seekers reached the city of Dawson. Dawson had been a small village before the discovery of gold. It became a big city within a short time. Stores and hotels were quickly built. The price of everything increased.
One man named Miller brought a cow to Dawson. He sold the milk for thirty dollars for a little less than four liters.
For the rest of his life he was known as "Cow Miller." He did not get rich seeking gold. But he made a great deal of money selling milk.
Many people did the same thing. They bought supplies in the United States and moved them to Dawson. Then they sold everything at extremely high prices.
The gold seekers quickly learned that most of the valuable areas of land had already been claimed by others. Many gave up and went home. Some gold seekers searched in other areas. Others went to work for people who had found gold.
Experts say about four thousand people became rich during the great Klondike gold rush. Groups of men formed large companies and began buying land in the area. The large companies used huge machines to dig for gold. One of these companies continued to make a profit digging gold until nineteen sixty-six. History records say that in only four years the area around Dawson produced more than fifty-one million dollars in gold. This would be worth more than one thousand million dollars today.
The great Yukon gold rush was over by the end of eighteen ninety-nine. As many of the gold seekers began to leave, news spread of another huge discovery of gold. Gold had been found in Nome, Alaska. Thousands of people rushed to Nome. Gold was later discovered in another part of Alaska in nineteen-oh-two.
Today, people visiting the area of the great Klondike gold rush can still find very small amounts of gold. The amount of gold is not much. But it is enough to feel the excitement of those gold seekers more than one hundred years ago.
This program was written by Paul Thompson. It was produced by Mario Ritter. This is Phoebe Zimmermann.
And this is Bob Doughty. Join us again next week for another EXPLORATIONS program in Special English on the Voice of America.
1. If miners traveling to Canada didn't have enough weight in their packs, _____________________ .
2. Soapy promised the miners that for five dollars, he would ________________ .
3. When men finally built their boats and made ready to journey down the Yukon River to the gold site, they could not make the trip because ___________________.
4. Many died journeying on the Yukon River because ___________________________ .
5. The number of people who became rich from the Yukon gold rush amounted to ___________________ .
6. More people made money selling ____________________ than actually finding gold.
7. The famous writer, ___________________ , went to the Yukon and described the very nightmarish conditions there.
8. By the time many miners arrived at the gold fields, they discovered that _________________________ .
9. The miners saw telegraph lines going up into the trees, but these hopeful miners didn't know that those telegraph lines __________________________ .
10. The great Yukon gold rush was over _______________________ .
The Yukon Gold Rush, Part One
Tuesday, March 2, 2010
BOB DOUGHTY: I’m Bob Doughty.
FAITH LAPIDUS: And I’m Faith Lapidus with EXPLORATIONS in VOA Special English. Today we go to New York City to visit the Museum of Chinese in America. Last year, MOCA reopened in a new and much larger building in the city’s Chinatown neighborhood.
The museum’s exhibits teach visitors about the art, culture and history of Chinese-Americans. MOCA says its aim is to show both the many layers of their experience and America’s development as a nation of immigrants.
BOB DOUGHTY: The Museum of Chinese in America may be in a newly restored building, but its roots go back thirty years. It began in nineteen eighty as a community organization called the New York Chinatown History Project. Activist Charles Lai and historian Jack Tchen were its creators. They realized that the memories and experiences of older generations of Chinese people in America were slowly disappearing. So, they decided to document these experiences by recording stories, taking pictures and collecting objects.
Jack Tchen has said that when he and Charles Lai started, there was no place to find true stories of Chinese people in New York. But he said there were many places to find stereotypes. A stereotype is a simplified and generalized idea about a group of people.
FAITH LAPIDUS: Ting-Chi Wang is exhibitions manager at MOCA. She took us on a guided visit of the museum. She leads us to a two-level room in the middle of the museum.
BOB DOUGHTY: Maya Lin is a Chinese-American building designer and artist. She is best known for designing the Vietnam Veterans Memorial in Washington, D.C. MOCA hired Maya Lin to design their new building. She turned an old industrial machine repair shop into a warm and inviting space for exhibitions, offices and classrooms.
TING-CHI WANG: “Maya Lin knew that history is very important for us, while we also want to emphasize the importance of looking forward.”
FAITH LAPIDUS: With this in mind, Maya Lin designed the building so that it has two entrances. They represent past and present, old and new. The main entrance faces the traditions of Chinatown. The other entrance faces the modernity of the neighborhood called SOHO.
The main exhibit wraps around the central courtyard. The courtyard walls contain several glass openings where videos are shown. They represent different periods of Chinese-American history.
BOB DOUGHTY: Ting-Chi Wang leads us to the permanent exhibition called “With a Single Step.” She says that the exhibition about Chinese immigrants in America was based on the idea of a hero’s travels.
TING-CHI WANG: “The concept of journey works out very well. In the sense that it’s literally, of course, a journey that the immigrants have taken, but also it’s the journey of America as country.”
FAITH LAPIDUS: The exhibit begins in the late seventeen hundreds and eighteen hundreds. It tells about the exchange of goods and people between China and western countries. And it tells about the role Chinese workers played in helping to build America into an industrial power.
The exhibit discusses the Opium Wars that took place in the middle of the nineteenth century. These trade disputes between China and Britain resulted in China being forced to open more of its ports to trade with western countries.
By eighteen eighty-two, Congress passed the Chinese Exclusion Act. The Exclusion Act suspended the immigration of Chinese workers into the United States. This was the first law in American history to put restrictions on immigration targeting one nationality. Chinese people trying to enter the United States would say they were related to families already in America by using false documents. These immigrants who tried to prove their family history to American officials this way were called “paper sons.”
Immigration was not completely reopened until the Immigration Act of nineteen sixty-five.
FAITH LAPIDUS: The museum tells about this history with personal photographs, documents, objects and videos. For example, a toy from the nineteenth century has two forms, a man in western clothing and a Chinese man. When you press the toy gun’s trigger, the western man kicks the Chinese man in the back. The racism represented by this object is hard to believe today. But it tells a great deal about social and political tensions during the late eighteen hundreds.
BOB DOUGHTY: The museum explores the complex situation of Chinese-Americans and how it has changed over time. For example, China became an ally of the United States during World War Two. But this alliance ended when China became a communist country in the nineteen fifties. And, the countries’ relationship changed again as China became a major trading partner.
FAITH LAPIDUS: One room in the museum is called the General Store. It includes thrown away objects collected from old stores in Chinatowns across the United States. Chinese-Americans formed strong communities in Chinatown neighborhoods within many cities. These include San Francisco, Boston, Los Angeles and Chicago. The exhibit shows the importance of such stores in these communities. Chinese-Americans could buy goods, mail letters and money home, get news about the community and meet with friends. Here is a nineteen eighty-eight recording of a man’s memories of his local general store.
LUNG CHIN: “The workers would come into this store at seven o’clock in the morning and work until twelve o’clock at night. Eighteen hours a day was nothing. And they slept there, they ate there, they had their lunch there. Their whole life was in that store, making money: saving it to go home, giving up money to send it back annually.”
BOB DOUGHTY: Many areas of the museum celebrate the successes of individuals.
TING-CHI WANG: “And on the inner wall close to the courtyard actually what you see are some glittering tiles, that’s what we call the luminary wall.”
FAITH LAPIDUS: But MOCA is not just interested in the past. It wants to look at what it means to be Chinese-American today and what it will mean looking forward.
One of its projects is called the MOCA StoryMap. This online project allows Chinese-Americans across the country to tell about their history and experiences. Google technology allows each person who tells a story to show where he or she lives on a map of the United States.
BOB DOUGHTY: One woman in Indianapolis, Indiana wrote about feeling very un-American while celebrating the Thanksgiving holiday with her parents.
Another man in Seattle, Washington writes about his family’s terrible experience fleeing first from China, then from Cambodia and Vietnam before arriving in the United States.
Ting-Chi Wang says the online stories are part of the MOCA collection that she hopes will become part of the permanent exhibit.
FAITH LAPIDUS: The Museum of Chinese in America also has temporary shows. Its current exhibit includes the work of twelve artists of Chinese ancestry who live in New York. The show is one of MOCA’s many efforts to move beyond generational, geographical and cultural boundaries in exploring Chinese-American identity.
BOB DOUGHTY: This program was written and produced by Dana Demange. I’m Bob Doughty.
FAITH LAPIDUS: And I’m Faith Lapidus. For a link to MOCA’s StoryMap project, visit our Web site, voaspecialenglish.com. Join us again next week for Explorations in VOA Special English.
1. Before it was a museum, MOCA was __________________________ .
2. MOCA hired _______________ to design their new building.
3. The MOCA StoryMap is an online project that allows Chinese-Americans to __________________ .
4. The Museum of Chinese in America is located in ______________ .
5. You're going to learn about nuclear physicist Chien-Shiung Wu by looking at the ___________________ .
6. A stereotype is ________________________________ .
7. The function of a courtyard in a traditional Chinese house is to ______________
8. In the nineteen fifties, China became _______________________ .
9. MOCA's aim is not only to show the culture of Chinese-Americans, but also to show ______________________ .
10. The Exclusion Act of 1882 _________________ the immigration of Chinese workers into the United States.
11. Working in a _________________ was known as the "eight-pound livelihood".
From a film program shown at MOCA: "Let the Caged Bird Sing"