From boyhood he was interested in Astronomy, and while at Cambridge he would sit up at night to watch the stars. But he was dissatisfied with the telescopes of those days because they didn't show him a clear picture of things. At first he thought there must be something wrong with the lens（镜头）. But no matter how hard he tried to improve the lens, the trouble was still there.

This set Newton thinking. He began to study the nature of light and colours. In the end he found that sunlight, or white light, is actually made up of a row of colours. He counted seven colours in all. This was of course a great discovery. But Newton still wasn't satisfied. His mind was busy with another problem. Before Newton's time, scientists had already discovered that the sun, not the earth, was the centre of the universe, and they knew that the earth and the other planets moved round the sun. But they couldn't explain why this was so until Newton gave the answer.

One autumn evening while Newton was sitting under an apple tree thinking over these problems, he saw the moon rise in the sky. Why, he asked himself, should the moon round the earth, never leaving the same path? At that moment, he heard an apple drop from the tree. Why should the apple drop to the ground? Why didn't it go sideways or fly up? There seemed to be only one reason: The earth was drawing it-that is the force of gravity. If a stone is tied to the end of a string and whirled around, it flies round and round in circles because of the string. In the same way, the force of gravity, thought Newton, must be the force that keeps the moon going round the earth and the planets round the sun.

When talking to babies, humans slow down their speech, raise their pitch (音高) and change the “color” of their voice. This “baby talk”, as people know it, increases the baby’s attention and facilitates language learning. Among animals, mothers often engage in child-directed vocalizations (发声) too, but does this also imply voice changes? A team of scientists that included Smithsonian Tropical Research Institute (STRI) researchers explored whether child-directed communication in bats resulted in vocalization changes.

They focused on a bat called Saccopteryx bilineata, a common Central and South American species with a remarkable vocal skill. During their first three months of life, as S. bilineata pups (幼崽) start experimenting with their “speech”, female and male adult bats respond to them differently. Through sound recordings of their vocal interactions, the research team found that mother bats “babble” as they interact with pups, which could be interpreted as delightful feedback to pups during vocal practice.

Much like human “baby talk”, the child-directed vocalizations of adult females presented a different “color” and pitch than the calls directed towards other adult bats. Male bats also communicated with the pups, but in a way that seemed to carry the “vocal signature” of their social group. “Pup isolation calls sound more similar to those of males from the same social group than to those of other males,” said Mirjam Knornschild, STRI research associate. “These results suggest that adult male vocalizations may serve as guidance for the development of group signatures in pup calls.”

This is the first time that scientists describe a phenomenon that could resemble “baby talk” among bats, indicating that parent-offspring communication in bats is more complex than previous thought and opening new avenues for further research.

“These results show that social feedback is important during vocal development, not only in humans but also in other vocal-learning species like Saccopteryx bilineata,” said Mirjam. “I believe that bats are a very promising species to investigate key shared features of language, such as the vocal learning ability, and that this study will inspire further studies in the biolinguistics field.”

Are you having difficulty falling asleep? Try drinking a glass of warm milk. If that doesn't work, listen to beautiful soft music. Still no luck? Try thinking about sheep jumping over a fence. If you are still awake, take a sleeping pill. But people who take pills often become dependent on the drugs. So you lie awake knowing that the new workday will soon arrive. If you have been in such condition for at least one month, you may have primary insomnia（失眠症）.

A new study has found that you might fall asleep more quickly and stay asleep longer if you try "cerebral hypothermia". It is not a complex medical process. It just means cooling down your brain. Eric Nofzinger and Daniel Buysse from the University of Pittsburgh Medical School led the study. They examined twelve people who had sleeping problems. Twelve others had no sleeping problems. Each of them wore a soft plastic cap on their head at bedtime.

The caps had tubes inside filled with water. The researchers moved the water through the tubes and then changed the temperature of the water. Other studies showed that people who had sleeping problems often had more chemical reactions in the front of their brains. The researchers thought cooling down the brain might help.

On the first two nights of testing, the patients wore caps with no water. On the next two nights, the caps were worn, but the water was not cooled. Then the researchers cooled the water a little for another two nights. On the final two nights of the study, the temperature of the water was made much cooler.

The researchers found that the water caps didn't help the patients until the temperature was about 14℃. Most of the patients fell asleep faster and slept better when the coolest water was moving around their heads.

Dr. Nofzinger and Dr. Buysse noted that this was only the beginning of the brain temperature study. But they believed they had discovered something important that needed more research.