Have you ever wanted to travel back in time? What about traveling into the future? There's an easy way to do it.

    One way you can make a time travel journey is by writing a letter to your future self to be opened in the future. To your future self, the letter will be a visit from the past. What can be gained by writing a letter to yourself? It depends on how good your letter is. You have the chance to say something to your future self. What would you want to communicate? You'll be able to talk to yourself 5, 10, 15 years down the road. There may be instructions for your future self, or you may have goals that you will want to check up on.

    There are a lot of things you could include in your letter or letters to yourself. The more you include, the better the letter will be to you. Here are some ideas of things to include in your letter:

    Your thoughts and feelings about life, religion, politics, society, etc.

Your feelings for your family.

Your likes and dislikes.

Your dreams.

    The type of person you want yourself to become.…

    Be creative with what you put in your letter. Include a picture of yourself or family to show the period from which the letter came.

    You can store your letter in many different ways. You can give your letter to a friend or family member to keep and mail to you. If you can get others to take part, have them write letters to themselves as well and ask someone to be the letter holder until it's time to send the letters. You can also use a service online to store your letter and e-mail it to you.

    Make the most of your letter writing, and you will help your future self make the most of the present.

    Electrical devices (仪器) could soon use power made by human energy. Scientists say they have developed an experimental device that produces electricity from the physical movement of a person walking. British scientist Max Donelan and other scientists in Canada and the United States developed the device.

    The device connects to a person's knee. As the person walks, the device captures energy each time the person slows down. To do this, the device helps with the slowing down movement of the leg. The movements of the walking person push parts of a small machine that produces electricity. Using the device, an adult walking quickly could produce thirteen watts of electricity in just a minute. Donelan says walking at that speed could produce enough power to operate a laptop computer for six minutes.

    There are several possible uses for the device. Developers say it could help people who work in areas without electricity to operate small computers. The device could also be used in hospitals to operate heart pacemakers (起搏器). It could even be used to assist in the movement of robotic arms and legs.

    The experimental version of the device weighs about one and a half kilograms, but it is too costly for most people to buy. But the researchers hope to make a lighter, less costly version. An improved version should be ready in one year.

    The developers hope the device will one day help developing countries. Nearly twenty-five percent of people around the world live without electric power.

    A similar product was invented in 2005 by Larry Rome of the University of Pennsylvania. He created a bag carried on a person's back that also produces power from walking. The knee device does not produce as much electricity as the bag. But the bag requires the walker to carry a load of twenty to thirty kilograms.

    "Are you going to Seattle?" an anxious-looking woman asked a female traveler at the Amtrak Airport in Sacramento. "No, I'm going to Eugene," the traveler replied. "Oh, I was hoping you could watch out for my daughter, she's never been on a plane before."

    Now, as I am quite a seasoned plane traveler, I know that seats and cars are supplied by destination（目的地）. So I came up to the woman and her frightened-looking daughter, telling them that her daughter could sit with me and that I would take care of her during the journey.

    The plane had arrived 25 minutes late, and people walked in line to get their seats. The conductor wanted to know if there were people traveling together, so I went to the front of the line with the girl and we were arranged to sit next to each other. Once on board, I showed her where to put her package, and took her to the bathroom area. Then we settled down to sleep. In the morning, I showed her the dining room and bought her a drink. She became comfortable enough to do what most 15-year-olds do: talk and text on her mobile phone.

    All through the trip, I made sure she picked up her ID, which had fallen out of her backpack, some money, which had fallen into the crack （缝隙） of the reclining seat, and continuously kept an eye on her. I hope someone takes her under their wing when she flies back to Sacramento.

    I do hope that kindness will spread around the world through these ways. We're conditioned to think that our lives go on with great moments. But great moments often catch us unaware, beautifully wrapped（包裹）in what others may consider a small one.

    Wilbur and Orville Wright were the two youngest sons of Bishop Milton Wright, Wilbur was born on a farm near Millville and Orville was born in August in the house the family would come to occupy for more than 40 years in Dayton.

    Orville would discover in later years that he and Wilbur's first interests in flight began when they were children, with powered rubber-band-helicopter toys that their father would bring home for them from trips around the country. Orville and Wilbur would build duplicates（复制品）of these toys and bounce them off the ceiling. They were just crazy about these things for the reasons that they did not yet understand.

    Both boys loved to solve problems that seemed difficult to others. The more difficult the problem was, the more they saw it as a challenge. Exploring the unknown was such a joy for then that Orville once said, "I can remember when Wilbur and I could hardly wait for the morning to come to get at something that interested us. That's happiness."

    Putting their gift to work, the boys entered the printing business soon after high school. Orville designed and then built a printing press（印刷机）for this enterprise. At first, they did contract printing for other people, and soon one of their customers during the early 1890s was Father Milton's church. They also tried the newspaper business, and although their two newspapers, the West Side News and The Evening Item were considered to be of high quality, Dayton already had daily newspapers, so the Wrights soon returned to contract printing.

    Branching out into other areas, they also opened a bicycle business. Bicycling was the fastest growing sport in the country at that time, and their repair shop soon led them into building bicycles of their own design, often with tools of their own construction, such as the lathe（车床）driven by a one-cylinder gasoline engine built by Orville. The bicycle shop would provide the livelihood（生计）that would allow them to carry out their experiments on airplanes.

    I had an experience some years ago, which taught me something about the ways in which people make a bad situation worse by blaming themselves. One January, I had to hold two funerals for two elderly women in my community. Both had died "full of years", as the Bible would say. Their homes happened to be near each other, so I paid condolence(吊唁) calls on the two families on the same afternoon.

    At the first home, the son of the deceased(过世的)woman said to me, "If only I had sent my mother to Florida and gotten her out of this cold and snow, she would be alive today. It's my fault that she died." At the second home, the son of the other deceased woman said, "If only I hadn't insisted on my mother's going to Florida, she would be alive today. That long airplane ride, the sudden change of climate, was more than she could take. It's my fault that she's dead."

    You see that any time there is a death, the survivors will feel guilty. Because the course of action they took turned out bad, they believe that the opposite course—keeping Mother at home, putting off the operation—would have turned out better. After all, how could it have turned out any worse?

    There seem to be two elements involved in our willingness to feel guilty. The first is our need to believe that the world makes sense, that there is a cause for every effect and a reason for everything that happens. That leads us to find patterns and connections both where they really exist and where they exist only in our minds.

    The second element is the view that we are the cause of what happens, especially the bad things that happen. It seems to be a short step from believing that every event has a cause to believing that every disaster is our fault. The roots of this feeling may lie in our childhood.

    A baby comes to think that the world exists to meet his needs, and that he makes everything happen in it. He wakes up in the morning and summons the rest of the world to his tasks. He cries, and someone comes to attend to him. When he is hungry, people feed him, and when he is wet, people change him. Very often, we do not completely outgrow that childish view that our wishes cause things to happen.

Brilliant Ways to Deliver Secret Messages

Many effective ways are used now to deliver secret messages. But in the past when the science and technology was not developing, especially during the war, how did people send secret and important messages?

Shoelaces

In the 1950s, the U.S. Central Intelligence Agency created a book of tips to teach spies ways to communicate in public. One tip: Lace up your shoes. Tied one way, the laces might mean "I have information": tied another, "Follow me". The spies could communicate while everyone else probably thought, "That guy can't tie his shoes correctly!"

Tattooed (刺文身) Head

Around 513 B.C., Histiaeus was forced out as the ruler of an ancient city. So he wanted to send a message to his supporters: Rebel against the king who took away his power.

Histiaeus called in a slave, shaved his head and tattooed the message onto the man's skin on the top of head. After the slave's hair grew back, he travelled to Greece with orders to shave his head again. Message received!

Orange Juice

In 1597, John Gerard was imprisoned in the Tower of London in England. He asked the prison guard to let him send letters written in charcoal (木炭). But then he wrote another message on top using the juice from an orange-which was only visible when the juice was dry and the page heated. With his invisible ink, he escaped successfully.

Songs

In the 1800s, African American slaves couldn't talk openly about their plans to escape to freedom—so they secretly sang about it.

Swing Low, Sweet Chariot might sound like a religious song. But for slaves, the "sweet chariot" was the code for the Underground Railroad, the network of people who helped slaves head to northern states and Canada. The song Wade in the Water warned escaped slaves to get in the water so dogs wouldn't smell them. With these songs, hundreds of people escaped slavery.