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.

How did Robert Boyle prove the properties of sound waves?

Flowing water causes sediment to move. Flowing water can erode both rocks and soil. You have already learned that materials can dissolve in water. With enough time, even rocks can be dissolved by water. This process happens really slowly. It may take over a million years to dissolve a rock. It doesnt matter how big the rock is. With enough time, flowing water can dissolve it. Moving water also has the ability to move small pieces of rock and soil. How can water move a rock? Doesnt it need energy? Of course, water gets its energy because it is moving. Moving water has kinetic energy. Things that have more energy can do more work. When water stops moving it will have no energy. It will no longer be able to move the rock and soil. When this happens the rock and soil will settle to the bottom of the calm water. Scientists call this process deposition.

What are some things flowing water causes?

New Legitimacy: Organized crime was soon to have a formidable adversary in its bid to control Las Vegascorporate cash. Though Las Vegas had developed a powerful local economy, few major outside investments were made in the city, due primarily to mob infiltration and its inherent ties to illegal activities. That would change dramatically with the 1966 arrival of billionaire Howard Hughes. A legitimate businessman, Hughes was nonetheless eccentric and dramatic, a style suited to the Las Vegas ethos. True to the myth, the reclusive Hughes immediately cloistered himself in the Desert Inn's penthouse. Several weeks later he was askedthen orderedto vacate the room to make room for high rollers, whereupon he promptly bought the property and fired the management. Thus began Hughes' legendary three-year, $300-million Las Vegas buying spree. When it was over, Hughes owned six casinos, an airport, and an airline, along with numerous plots of land stretching from the Strip to the mountains. Hughes' actions would have beneficial repercussions, both immediate and lasting. Because of the new legitimacy Las Vegas acquired from Hughes' investments, established companies such as Hilton Hotels bought into the gaming business, and their influence helped draw a line in the desert sand between legitimate operations and mob casinos, where illegal skimming of profits was rampant. That, combined with the formation of the Nevada Gaming Control Board, would signal the beginning of the end for heavy mob influence in the city. Las Vegas with a Vision As corporations moved in and the mob was slowly pushed out, a new Las Vegas emerged. The legitimization of gambling led to its increased legalization across the US. What was once a sure thing became much more competitive. Casino operators had to reassess the nature of their business. The first to really do so was Steve Wynn, a Las Vegas resident and owner of the Golden Nugget. In the mid-1980s, Wynn began plans to reinvigorate Las Vegas with a new resort. He bought several Strip propertiesthe Silver Slipper and Castaways among themand demolished them to make way for a new kind of resortMirage which became an instant success.
What did Howard Hughes purchase during his Vegas buying spree?