For years, people have wondered whether there's life on other planets. Scientists may now be closer than ever to answering that question.

    Using powerful telescopes, a team of astronomers in South America discovered a new planet, called Proxima b. It circles a star named Proxima Centauri, in the same way Earth circles the sun. Proxima Centauri is the closest star to our solar system.

    Scientists believe the new planet has a rocky surface and is similar in size to Earth. More important, they've determined that the distance between Proxima b and its “sun” gives the planet a similar temperature to Earth's.This means it could have liquid water. The presence of water on a planet makes it possible for life to exist there. Scientists refer to planets like Proxima b as “Goldilocks planets” because they are not too hot or too cold, but just right to possibly support life.

    Astronomers have found other Goldilocks planets in the past, but none are as close to Earth as Proxima b. Still, the new planet is 4.2 light years from Earth—that is about 25 trillion miles away.

    Despite the long distance, astronomers hope to get a much better look at our new-found neighbor one day. But they'll need to wait until more advanced telescopes are developed. They may also send a robotic spacecraft to investigate the planet.

    A “lost tribe” that reached America from Australia may have been the first Native Americans, according to a new theory.

    If proved by DNA evidence, the theory will break long established beliefs about the southerly migration of people who entered America across the Bering Strait, found it empty and occupied it.

    On this theory rests the belief of Native Americans to have been the first true Americans. They would be classified to the ranks of escapee, beaten to the New World by Aboriginals (土著人) in boats.

    To a European, this may seem like an academic argument, but to Americans it is a philosophical question about identity, Silvia Gonzales, of Liverpool University said.

    Her claims are based on skeletons found in the California Peninsula of Mexico that have skulls quite unlike the broad Mongolian features of Native Americans. These narrow-skulled people have more in common with southern Asians, Aboriginal Australians and people of the South Pacific Region.

    The bones, stored at the National Museum of Anthropology (人类学) in Mexico City, have been carbon-dated and one is 12,700 years old, which places it several thousand years before the arrival of people from the North. “We think there were several migration waves into the Americas at different times by different human groups,” Dr. Gonzales said. “The timing, route and point of origin of the first colonization of the Americas remains a most contentious topic in human evolution.”

    But comparisons based on skull shape are not considered conclusive by anthropologists, so a team of Mexican and British scientists, backed by the Natural Environment Research Council, has also attempted to take out DNA from the bones. Dr. Gonzales declined yesterday to say exactly what the results were, as they need to be checked, but indicated that they were consistent (一致) with an Australian origin.

    A cancer-stricken British teenager said on Thursday she had been moved by messages of support from around the world after writing an online “Bucket List” of things she wanted to do before dying.

    Alice Pyne, 15, created an Internet blog in which she described her fight against a cancer of the white blood cells. “I've been fighting cancer for almost four years and now I know that the cancer is gaining on me and it doesn't look like I'm going to win this one,” she wrote.

    For her list, at the site www. alicepyne. blogspot. com, she has included making everyone sign up to be a bone marrow donor (骨髓捐赠者), swimming with sharks, meeting boy band Take That and getting a purple iPad computer.

Messages of support and offers of help quickly flooded her webpage and it became one of the most talked about subjects on Twitter.

     “Oh dear! And I thought that I was just doing a little blog for a few friends!” she wrote after her site attracted huge attention. “Thank you so much for all your lovely messages to me.”

    Alice, who lives with her family in the northwest English town of Ulverston, said the manager of Take That had arranged for her to see the band after reading her blog. A group of local lawmakers have also made efforts with the Anthony blood cancer charity to encourage people to join its stem cell (干细胞) projects.

    AlphaGo is a computer program that plays the board game Go.

    In March, 2016, the pride of humankind was crushed (粉碎) by a computer. Google's AlphaGo defeated the South Korean grandmaster (围棋大师) Lee Sedol four games to one, as the world looked on with shock and awe (敬畏). Artificial intelligence (AI, 人工智能) had suddenly reached a new and unexpected height.

    But as smart as AlphaGo is, it's no longer the best Go “player” in the world. Google's artificial intelligence group, DeepMind, has created the next generation of its Go-playing program, called AlphaGo Zero. The new AI program is unique in the way it learned to play Go. Instead of learning from thousands of human matches, as its predecessor (前任) did, AlphaGo Zero mastered Go in just two days without any human knowledge of the game and defeated AlphaGo by day three, reported The Guardian. It then went on to defeat AlphaGo 100 games to zero.

    To learn how to play Go, AlphaGo Zero played millions of matches against itself using only the basic rules of the game to rapidly create its own knowledge of it. Like the previous version, it used “reinforcement (增强) learning to become its own teacher,” according to DeepMind's website.

    “It's more powerful than previous approaches,” David Silver, AlphaGo's lead researcher, told The Guardian, “because by not using human data, or human expertise in any fashion, we've removed the constraints (约束) of human knowledge and it is able to create knowledge itself.”

    AlphaGo Zero's approach to self-learning is a significant advancement in AI that could be applied to help solve some of the world's biggest problems, according to a recent research report published in the journal Nature. For example, DeepMind co-founder Demis Hassabis argues that AlphaGo Zero could probably find cures for a number of serious diseases within weeks, according to The Telegraph. Indeed, the AI is now being used to study protein folding, which is connected to diseases such as Parkinson's and Alzheimer's.

    So now that AI has exceeded (超过) the bounds of human knowledge, perhaps the question is not about what AI can learn from humans, but what humans can learn from AI. We can only wait and see.

    A great invention by an 18-year-old high school student grew out of a simple problem most teenagers meet with.

    “I'm a teenager and I have a cellphone and my cellphone battery always dies，so I was really looking for a way to improve energy storage，” Eesha Khare said on Tuesday. “That's how I came across the super capacitor.”

    The teenager who came from California, and graduated from high school last week，won a $50，000 prize on May 17，2013 at the Intel International Science and Engineering Fair for creating a device that can store enough energy to charge a cellphone in 20 to 30 seconds.

    “It charges very quickly and can store a lot of energy，” Khare said. “The cool thing is that it's a lot thinner than one strand of hair.”

    Khare hasn't used her invention to recharge a cellphone yet，but she used it to power a light-emitting diode (LED) in order to show its capability(容量). If used on cellphones，the supercharger would slide on to the phone's battery to juice it up in a matter of seconds. The technology isn't available to consumers yet，and it could be years until it is.

    At an Intel event in Phoenix，Khare won the Intel Foundation Young Scientist Award，taking second place overall in the world's largest high school science research competition. She beat out more than 1，600 finalists from 70 countries. She said that she has been approached by several companies to continue her research，but she is now focused on attending Harvard University in autumn.

    “Right now，just my education，but hopefully we'll see what happens in the future，” she said about her plans. “I have a lot of interests，so we'll see what I do in the future.”

    Most birds produce short, simple calls, but songbirds also have the ability of many complex vocal (发声的) patterns that help them attract mates, defend territory (领地), and strengthen their social bonds. Each songbird species has its own unique song patterns, some with characteristic regional dialects. Experienced listeners can even distinguish individual birds by their unique songs.

    A lot of what scientists know about bird song comes from studying zebra finches. A baby male zebra finch typically learns to sing from its father or other males, starting while it's still a baby bird in the nest. First comes the sensory learning stage, when the baby finch hears the songs sung around it and commits them to memory. The bird starts to vocalize during the motor learning stage, practicing until it can match the song it memorized. As the bird learns, hearing the tutor's song over and over again is helpful — up to a point. If it hears the song too many times, the imitation (模仿) becomes worse -- and the source matters. If the song is played through a loudspeaker, he can't pick it up as easily. But hide the same loudspeaker inside a toy painted to look like a zebra finch, and his learning improves.

    What if the baby never hears another zebra finch's song? Interestingly enough, it'll sing anyway. Isolated finches still produce what are called innate songs or isolate songs. A specific tune might be taught, but the instinct to sing seems to exist in a songbird's brain. Innate songs sound different from the “cultured” songs learned from other finches - at first. If isolate zebra finches start a new colony, the young birds pick up the isolate song from their fathers. But the song changes from generation to generation. And after a few generations, the melody actually starts to resemble the cultured songs sung by zebra finches in the wild.