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? Depends on how good your letter is. You have the chance to say something to your future self. What would you want to say? 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 reach.

    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. 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. Ready to write to yourself two and a half years down the road?

    The Healthy Habits Survey shows that only about one third of American seniors have correct habits. Here are some findings and expert advice.

    That the US stock market dropped sharply immediately after the US government put forward the proposal on Tuesday to tighten the control on exports of various artificial intelligence technologies indicates what the market thinks of the move.

    Multi-national corporations have led the way in the profound compressing(压缩) of time and space that has flattened and changed the world over the last couple of decades, and the overwhelming majority of international technological transfers have been conducted among multi-national companies in pursuit of profits.

    Thus the proposal the US government put forward on Tuesday to tighten the control to "avoid negatively impacting US leadership in the science, technology, engineering and manufacturing sector" is being viewed not only as a brake on the US economy but also as a barrier to maintaining that leadership since it will reduce cooperation with the rest of the world and shrink the market for US companies preventing them from investing research and development.

    The bigger its market, the more profits a technology company can earn, and the more money it then has to invest in developing even more advanced technologies. This is as true for US companies as it is for others.

    Behind the proposal is the narrow-mindedness of policymakers in the US administration, who choose to ignore the fact that the United States would not have become the world leader in science and technology if it had kept its doors closed.

    If such controls are intended to contain China's development, they will certainly fail.

    It is true that China has a lot to do to catch up with the US and other developed countries. Yet it has made great steps forward by opening its doors and cooperating with other economies.

    As it opens its door wider, it will have even more opportunities to cooperate with other countries in science and technology.

The de-materialization of economic activities — with economic output and income generation increasingly reliant on information rather than inputs of raw materials — only increases the need for cooperative agreements and a cross-disciplinary approach to increase the capabilities of AI and advance its application.

    By trying to enforce and exploit an invented-here ideal that is untenable, the US will undoubtedly lose the leadership in science and technology gradually to which it has become accustomed, and prevent the progress of both humans and machines.

    In Europe, there is no escape for those who do not appreciate art and architecture(建筑). It is a heaven for people who want to feel like they have been transported to famous historical time periods from America. For me, Europe was a complete contrast from America. London and France had a more royal feel than New York, and Rome felt more ancient. I wasn't just on a different continent; it felt like I was in a different century.

    My parents and I visited London, Paris and Rome this summer in celebration of the end of my high school experience. It was supposed to be a break from a life as busy as a bee in New York, the constant stress, the crowded subway rides, and the weary body that had accompanied me for the last four years. It was an opportunity to appreciate Europe the way I couldn't do it just by reading history books.

    My favorite parts of London were the Tower of London and the Churchill War Rooms. As a site of past executions(刑场), the Tower of London displayed punishing devices from the 16^th and 17^th century and told stories of various members of the royal family who had ever been imprisoned in the tower, some even imprisoned by their own family members when they were seen as a threat to the crown. Besides that, I also got to see the royal family's crown jewels, amazingly beautiful.

    The Churchchill War Rooms, though very different from the Tower of London, were also spellbinding from a historic perspective. I am not a history fan, but I enjoy museums, and I took fancy in the Churchchill Museum inside the War Rooms that detailed the events of Churchchill's life and World War II. Everything I saw in it built up his life from his childhood to his last years, creating a three-dimensional Churchchill in my mind who was a person just like myself. He longed for more, he made mistakes, he experienced loneliness and sadness. But he had also done some remarkable things like uniting Britain during World War II.

    Our rewarding trip ended in Rome a couple of days later.

    Friends always ask why I, a middle-aged woman with no athletic talent, travel to perilous places—the jungles of Thailand or Borneo, for example, where the water is often unsafe and the food risky; places with infectious diseases, poisonous snakes and the wildest animals; some places where the locals are just a few generations past headhunting.

    I never know how to answer. My travel decisions assumed a new gravity nine years ago after I suffered a stroke. To prevent another stroke, my doctors told me, I'd have to take dangerously high levels of blood thinner (血液稀释剂) for the rest of my life and any travel would be risky.

    I had to think about what was important to me: family, of course, and friends. But then what? No matter how many times I thought about it, no bucket list was complete without travel. Then I had to decide how I might manage the risk. I had to decide how lucky I felt.

    My return to travel after my stroke came in baby steps. The first real test of my travel courage came nine months after my stroke when I joined my husband, Jack, on a business trip to China. After we'd toured the remains of a Tang dynasty temple on a high mountain, Jack wanted to ride down on a toboggan (长雪橇).

    Before the stroke it would've seemed like fun. But now? I hesitated. My mental klaxon (高音喇叭) screamed warnings about the consequences of a cut, a fall, and a crash. Then, gaining confidence from who knows where, I lowered myself carefully into the toboggan, which marked my adventure travel comeback.

    In the years since then, I've traveled about twenty-five percent of the time. Through it all, my lucks held out—no deadly falls, no car accidents or serious infections. For me, adventure travel is a risk worth taking. Travel broadens my world and keeps me connected to nature. What's more, saying "yes" to travel keeps me connected to myself.

    It's already challenging enough for environmentalists to keep beaches clear of washed up trash(垃圾) and plastic debris(残骸), but the most difficult problem lies in cleaning up all of the millions of tiny microplastics that are impossible to pick up and separate from the sand.

    Fortunately, a group of engineering students succeeded in developing a massive new vacuum cleaner that can collect microplastics without removing any of the sand from the beach. The 12 Canadian students from the University of Sherbrooke in Quebec built their Hoola One plastic vacuum cleaner as a class project.

    "We did some research and we realized there was no machine around the world to do this kind of job," Hoola One co-founder Sam Duval told Hawaii Public Radio. "So we told each other, 'We will invent it,' and we did it."

    As a means of testing their machine's efficiency, they recently used it on the sands of Hawaii's Kamilo Beach, which is also notorious for being one of the dirtiest beaches in the world. Though their first prototype(原型)experienced a number of technical issues, the students managed to fix the problems and tidy up the beach.

    Using a handheld tube, the machine sucks(吸入)up plastic and sand and dumps them all into a massive tank of water. Since rocks and sand are heavier than plastic, they sink to the bottom of the tank so they can be dumped back onto the beach. The plastic, on the other hand, floats to the top of the tank.

    According to Hawaii Public Radio, the team left the Hoola One vacuum on the island as a donation to the state department- They are now researching the ecological effects of the vacuum on the beach while they search for funding and sponsorships(赞助)to produce more Hoola One vacuums.