No one is sure how the ancient Egyptians built the pyramids near Cairo. But a new study suggests they used a little rock‘n'roll. Long-ago builders could have attached wooden pole s to the stones and rolled then across the sand, the scientists say.
“Technically, I think what they're proposing is possible,” physicist Daniel Bonn said.
People have long puzzled over how the Egyptians moved such huge rocks. And there's no obvious answer. On average, each of the two million big stones weighed about as much as a large pickup truck. The Egyptians somehow moved the stone blocks to the pyramid site from about one kilometer away.
The most popular view is that Egyptian workers slid the blocks along smooth paths. Many scientists suspect workers first would have put the blocks on sleds(滑板). Then they would have dragged them along paths. To make the work easier, workers may have lubricated the paths either with wet clay or with the fat from cattle. Bonn has now tested this idea by building small sleds and dragging heavy objects over sand.
Evidence from the sand supports this idea. Researchers found small amounts of fat, as well as a large amount of stone and the remains of paths.

However, physicist Joseph West thinks there might have been a simpler way , who led the new study . West said , “I was inspired while watching a television program showing how sleds might have helped with pyramid construction . I thought , ‘Why don't they just try rolling the things?'“A square could be turned into a rough sort of wheel by attaching wooden poles to its sides , he realized . That , he notes , should make a block of stone” a lot easier to roll than a square”.
So he tried it.
He and his students tied some poles to each of four sides of a 30-kilogram stone block. That action turned the block into somewhat a wheel. Then they placed the block on the ground.
They wrapped one end of a rope around the block and pulled. The researchers found they could easily roll the block along different kinds of paths. They calculated that rolling the block required about as much force as moving it along a slippery(滑的)path.
West hasn't tested his idea on larger blocks, but he thinks rolling has clear advantages over sliding. At least, workers wouldn't have needed to carry cattle fat or water to smooth the paths.

    How to deal with waste has been a problem since humans started producing it. As more and more people choose to live close together in cities, the waste-disposal (处理) problem becomes increasingly difficult.

    During the eighteenth century, it was usual for several neighboring towns to get together to select a faraway spot as a dump site. Residents or trash haulers (垃圾拖运者) would transport household rubbish, rotted wood, and old possessions to the site. Periodically (定期的) some of the trash was burned and the rest was buried. The unpleasant sights and smells caused no problem because nobody lived close by.

    Factories, mills, and other industrial sites also had waste to be disposed of (处理). Those located on rivers often just dumped (倾倒) the unwanted remains into the water. Others built huge burners with chimneys (烟囱) to deal with the problem.

    Several facts make these choices unacceptable to modem society. The first problem is space. Dumps, which are now called landfills, are most needed in heavily populated areas. Such areas rarely have empty land suitable for this purpose. Property is either too expensive or too close to residential (住宅区的) neighborhoods. Long-distance trash hauling has been a common practice, but once farm areas are refusing to accept rubbish from elsewhere, cheap land within trucking distance of major city areas is almost nonexistent (不存在).

    Awareness (意识) of pollution dangers has led to more strict rules of waste disposal. Pollution of rivers, ground water, land and air is a price people can no longer pay to get rid of waste. The amount of waste, however, continues to grow.

    Recycling efforts have become commonplace, and many towns require their people to take part. Even the most efficient recycling programs, however, can hope to deal with only about 50 per cent of a city's reusable waste.

    The Dickens Exhibition

    Date： 9 June, 2018—10 December, 2018

    Location: Museum of London

    It celebrates the 205th anniversary of the birth of Charles Dickens. By recreating the atmosphere of Victorian London through sound and projections (投影画），you'll be taken on an unforgettable journey to discover the city that inspired his writings.

    Paintings, photographs， costumes and objects will explain different themes that Dickens wrote into his works， while rarely seen manuscripts (手稿）including Bleak House and David Copper field will offer introduction to his creative genius.

    During your visit you'll discover how Dickens' childhood experiences of London were introduced into the stories he wrote. The great social questions of the 19th century will also be examined, all of which set the scene for Dickens' greatest works.

    Highlights of the exhibition will include an exciting audio-visual experience, and a special film shot by one of the UK's leading documentary filmmakers.

    Packages include afternoon entry (1:00 pm—4:00 pm) to the exhibition plus overnight accommodation at a nearby hotel. If you wish to visit the exhibition the day after your hotel stay, please call our reservation department. Call： 08712212717.

    Book a trip online with us, with tickets to Dickens London Exhibition afternoon entry and hotel accommodation included in the price. All taxes included. No credit card fees No booking fees. No discount.

    Price Information： a package costs an adult £120 and a child (age 4 — ^5)尤⑻ afternoon entry costs an adult £28 and a child (age 4 — 15) £14.

    I went up to Peet's Coffee the other morning and there was a young man, Mike, probably my age. With him he had all his physical belongings on a small roll cart. I first thought, how nice to have so few possessions. That was followed with the thought of how ironic (讽刺的) it is that we live in one of the financially wealthiest areas of the U.S., if not the world, yet we can't, or don't, take care of the basic needs of human beings. Yes, we are financially wealthy, but we lack in wealth of compassion (同情), kindness, and understanding. I tear up as I ponder the inequality and injustice that exists.

    Anyway, I invited Mike in for a bite to eat and he eagerly accepted. He talked about looking up a friend for a place to stay that night. On Christmas Eve as many eagerly and greedily stuff their bellies with food in nice, warm homes and then open presents, Mike just wanted a place to spend the evening.

    Then I was really blown away. As he waited for his sandwich, Mike began cleaning up the condiment (佐料) area. He took some paper and wiped up the spills of others and rearranged the milks and other condiments, making everything neat and orderly. Here is a person with very little and he's serving others in a way that's just natural to him.

    I spoke with Mike about this afterward, thanking him. He said he always did that sort of thing—straightening up. To him, it was just common politeness. I just asked him for a hug and we parted to go our separate ways. There is a lot for us...me... to learn in the most unlikely place.

    Our most important institutions, our schools and our workplaces, are designed mostly for extroverts (性格外向者).

In the typical classroom, students are often divided into groups—four or five or more kids all facing each other. And kids are working on countless group assignments. Even in subjects like math and creative writing, which you think would depend on unaccompanied flights of thought, kids are now expected to act as committee members. As for the kids who prefer to go off by themselves or just to work alone, those kids are seen as outliers (局外人) often or, worse, as problem cases. And the vast majority of teachers believe that the ideal student is an extrovert as opposed to an introvert (性格内向者), even though introverts actually get better grades and are more knowledgeable, according to research.

The same thing is true in our workplaces. Now, most of us work in open plan offices, without walls, where we are subject to the constant noise and stare of our coworkers. And when it comes to leadership, introverts are routinely passed over for leadership positions, even though introverts tend to be very careful, much less likely to take outsize risks —which is something we might all favor nowadays. And interesting research by Adam Grant at the Wharton School has found that introverted leaders often deliver better outcomes than extroverts do, because when they are managing thoughtful employees, they're much more likely to let those employees run with their ideas.

    In fact, some of our great leaders in history have been introverts. I'll give you some examples. Eleanor Roosevelt, Rosa Parks, Gandhi -- all these people described themselves as quiet and soft-spoken and even shy. However, they all took the spotlight, even though every bone in their bodies was telling them not to. And this turns out to have a special power, because people could feel that these leaders were in control, not because they enjoyed directing others and not out of the pleasure of being looked at; they were there because they had no choice, because they were driven to do what they thought was right.