QUES: Sound waves are mechanical waves. They can travel only through matter. They cannot travel through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air out of the jar. The clock was still running, but the ticking could not be heard. Thats because the sound couldnt travel without air particles to transfer the sound energy. Is there any other place where sound cannot be heard? Here is a hint: is there any other place that does not have air molecules? Thats right, in space sound cannot be transferred. So can astronauts hear each other? Yes, they can, because they are in enclosed space stations or pressurized suits.In both cases, they are surrounded by air molecules. If they left their space ship and did not use their electronics, they would not be able to hear each other. Next time you watch a science fiction movie, think about this factoid. When spaceships are destroyed by hostile alien beings, there would be no sound heard. Sound waves can travel through many kinds of matter.
Do you have any questions?
MY QUESTION: How do astronauts hear each other?

QUES: Tuesday, September 11, 2001, dawned temperate and nearly cloudless in the eastern United States. Millions of men and women readied themselves for work. Some made their way to the Twin Towers, the signature structures of the World Trade Center complex in New York City. Others went to Arlington, Virginia, to the Pentagon. Across the Potomac River, the United States Congress was back in session. At the other end of Pennsylvania Avenue, people began to line up for a White House tour. In Sarasota, Florida, President George W. Bush went for an early morning run. For those heading to an airport, weather conditions could not have been better for a safe and pleasant journey. Among the travelers were Mohamed Atta and Abdul Aziz al Omari, who arrived at the airport in Portland, Maine. Boston: American 11 and United 175. Atta and Omari boarded a 6:00 A.M. flight from Portland to Boston's Logan International Airport. When he checked in for his flight to Boston, Atta was selected by a computerized prescreening system known as CAPPS (Computer Assisted Passenger Prescreening System), created to identify passengers who should be subject to special security measures. Under security rules in place at the time, the only consequence of Atta's selection by CAPPS was that his checked bags were held off the plane until it was confirmed that he had boarded the aircraft. This did not hinder Atta's plans. Atta and Omari arrived in Boston at 6:45. Seven minutes later, Atta apparently took a call from Marwan al Shehhi, a longtime colleague who was at another terminal at Logan Airport. They spoke for three minutes. It would be their final conversation.
Do you have any questions?
MY QUESTION: What was the weather like when President George W. Bush went for his early morning run?

QUES: The inhabited history of the Las Vegas Valley stretches to 23,000 b.c. , when much of the area was covered by a prehistoric lake. During this period, the indigenous people lived in caves, hunting the mammals that gathered at the shoreline. The landscape of the valley changed dramatically over the next 200 centuries. The glaciers feeding the lake melted away and the lake evaporated. Fossils tell an obscure story of man's slow and sporadic development. Around 3000 b.c. , native Archaic Indians began to develop a lasting hunting and gathering culture. By this time, the valley was in much the same geographic state as it exists in today, with one exceptionthe presence of artesian springs that bubbled to the surface in several areas. These springs fed a network of streams draining through the Las Vegas Wash to the Colorado River. The areas surrounding the springs were desert oases: sprawling collections of grasses, trees, and wildlife. Many springs lay in areas that would eventually become the center of the modern Las Vegas metropolis. For about 4000 years, the Archaics thrived in a culture that included many signs of early civilization. Signs of even more advancement appeared halfway through the first millennium a.d. , when the Anasazi Indians inhabited the valley. Far more progressive than the Archaics, the Anasazi utilized such formal agricultural techniques as irrigation to assist their harvest. This permitted the Anasazi to achieve a benchmark of advanced societythe ability to live in permanent shelters year-round without need to follow wildlife. Mysteriously, the Anasazi vanished from the valley around a.d.
Do you have any questions?
MY QUESTION: Who was the most advance early civilization that disappeared in Las Vegas?

QUES: Over the centuries, the living here has always been easy enough to attract a steady stream of immigrants. Bountiful food sources might have made Malaysia an inviting place for the contemporaries of Java Manin 230,000 b.c. But thus far, the country's earliest traces of homo sapiens, found in the Niah Caves of northern Sarawak, are fragments of a skull dating to 40,000 b.c. On the peninsula, the oldest human-related relics (10,000 b.c. ) are Stone Age tools of the Negritos. These small, dark Melanesians are related in type to Australian aborigines and are confined today to the forests of the northern highlands. By 2,000 b.c. , these timid, gentle nomads hunting with bow and arrow were driven back from the coasts by waves of sturdy immigrants arriving in outrigger canoes equipped with sails. Mongolians from South China and Polynesian and Malay peoples from the Philippines and the Indonesian islands settled along the rivers of the peninsula and northern Borneo. They practiced a slash-and-burn agriculture of yams and millet, a technique that exhausted the soil and imposed a semi-nomadic existence from one jungle clearing to another. Families lived in wooden longhouses like those still to be seen today among the Iban peoples of Sarawak. Another unit was added on to the communal dwelling each time a marriage created a new family. Other tough migrants from the South Seas settled along the coastssailors, fishermen, traders (for the most part pirates)known euphemistically as orang laut (sea people).
Do you have any questions?
MY QUESTION:
Why did the wooden longhouses grow larger over time?