【推荐1】Have you ever wondered why certain pop songs just make you feel so good? Researchers studying the question found that uncertainty and surprise give listeners the most pleasure. The study included 80,000 chords（和弦）in 745 pop songs between 1958 and 1991.

Each song was stripped of its melody（旋律）and lyrics（歌词）so that only chords were left and the results couldn^’t be misunderstood by other imaginations of the songs that listeners might have had.

They found two things. Listeners got great pleasure from unexpected chords when they knew what would happen. However, they still found it pleasant to hear familiar chords when they did not know what would follow.

Vincent Cheung, the lead researcher, said, "Pleasant songs are likely those which keep a good balance（平衡）between knowing what is going to happen next and surprising us with something we did not expect. Understanding how music starts our pleasure system in the brain could explain why listening to music might help us feel better when we are feeling blue.”

Cheung told CNN that pleasure in music is connected to expectation. The study before had looked into the effects of surprise on pleasure, but his team's study also paid attention to the uncertainty of listeners' expectations.

【推荐2】A few hours after my first mission, returning to Earth on the space shuttle Endeavour, I completed all of my medical tests after the flight, met with NASA officials, and reunited with my family. Finally, I was alone in my office room in astronaut crew quarters at the Kennedy Space Center. I turned on the TV. The television news started up: Such and such happened, people were shocked, blah blah blah. Sports scores. Silly commercials.

It didn’t take more than a minute before I had to turn it off. It felt like my body was refusing all this input, just as it would refuse an organ donation that had the wrong blood type. All of this noise was just completely foreign to who I was—or, more appropriately, who I had become. A few hours before, I had been orbiting Earth, seeing our planet from space, flying the most amazing machine ever built by human hands, and working with a team that was the absolute success of humans. And now here in my room watching what was being sold as news, and with my newfound perspective, I just could not stomach it. My world view was changed forever in a profound (深刻的) way.

The biggest change by far and the one for which I will always be most grateful is this big-picture perspective. That will stick with me for the rest of my life.

Whenever I feel the pressure of modern life, the stress about work, or worry about the future, I remember my time in the space station. Back to seeing the sun set. Or watching our galaxy rise on the horizon. Or seeing a sea of lightning flash a hundred times a second. Or simply back to floating weightlessly.

When I’m there in my mind and realize how many billions of these beautiful sunsets there have been and will be in the future, the cares of the world just don’t seem that pressing. It goes that, “Do not worry about tomorrow, for tomorrow will worry about itself.” Living daily life down here on the planet is so much better with this attitude!