Why Do We Yawn?
为什么我们会打哈欠？
Have you ever yawned in class and made your neighbour yawn too? Scientists call this "contagious yawning." But why do we yawn at all? One popular idea is that yawning cools the brain — like opening a window on a hot day. Another theory says yawning helps us stay alert when we feel tired. Even dogs and fish yawn! Nobody knows the full answer yet. Sometimes science is as mysterious as a good question.
你有没有在课上打了个哈欠，然后旁边的同学也跟着打？科学家把这叫做“传染性哈欠”。但我们为什么会打哈欠呢？一种流行的说法是，哈欠能给大脑降温——就像在炎热的天气里打开窗户。另一种理论认为，哈欠帮助我们在疲倦时保持清醒。连狗和鱼也会打哈欠！目前还没有人完全弄清楚原因。有时候，科学本身就像一个好问题一样神秘。
The Ocean Genius: Octopus
海洋天才：章鱼
An octopus has three hearts, blue blood, and nine brains — one central brain and one in each arm. Each arm can taste, touch, and even think on its own! Octopuses can open jars, escape from tanks, and change colour in less than a second. They have no bones, so they can squeeze through any hole big enough for their eyes. The ocean is full of surprises, and the octopus is one of its greatest.
章鱼有三颗心脏、蓝色的血液，还有九个大脑——一个中央脑，加上每条触手里各一个。每条触手都能感知味道、触觉，甚至独立“思考”！章鱼能打开瓶盖、逃出鱼缸，还能在不到一秒内改变体色。它们没有骨头，所以只要洞口够眼睛通过，全身就能穿过去。海洋充满惊喜，而章鱼就是其中最精彩的惊喜之一。
Salt: The Seasoning That Changed History
盐：改变历史的调味料
Salt is so common today that we forget how powerful it once was. Roman soldiers were sometimes paid in salt — that's where the word "salary" comes from. In ancient China, salt traders became some of the richest people in the country. Before refrigerators, salt was the only way to preserve meat and fish. Wars were fought over salt, and cities were built near salt mines. Something so simple shaped the whole world.
今天的盐太普通了，我们忘记了它曾经有多重要。古罗马士兵有时会用盐来代替薪水——“salary（薪水）”这个词就来源于此。在中国古代，盐商是国内最富有的人之一。冰箱发明之前，盐是保存肉类和鱼类的唯一方式。人们为盐而打仗，在盐矿附近建起城市。如此简单的东西，却塑造了整个世界。
The Moon Has No Weather
月球没有天气
On the Moon, there is no wind, no rain, and no clouds. The sky is always black, even during the day. Because there is no air, sound cannot travel — it is completely silent. The footprints left by Apollo astronauts in 1969 are still there today, perfectly unchanged. Nothing has moved them. On Earth, footprints disappear in minutes. On the Moon, they may last for millions of years. The Moon keeps every memory it has.
月球上没有风、没有雨、也没有云。天空永远是黑色的，即使在白天也一样。因为没有空气，声音无法传播——那里完全静默。1969年阿波罗宇航员留下的脚印至今还在，丝毫未变。没有任何东西能移动它们。在地球上，脚印几分钟就会消失。而在月球上，它们可能留存数百万年。月球珍藏着它所有的记忆。
Where Does Your Rubbish Go?
你的垃圾去了哪里？
After you throw something away, the journey is just beginning. Rubbish trucks collect waste from streets and homes. Some goes to recycling centres, where machines sort plastic, paper, and glass. Food waste can become compost for gardens. Some rubbish goes to landfill — huge holes in the ground — where it slowly breaks down over hundreds of years. A single plastic bottle takes 450 years to disappear. The bin is not the end. Think before you throw.
当你扔掉一样东西时，它的旅程才刚刚开始。垃圾车从街道和住宅收集废物。一部分被送往回收中心，机器在那里分拣塑料、纸张和玻璃。食物废料可以变成园艺用的堆肥。还有一些垃圾被送往垃圾填埋场——地面上的巨大坑洞——在那里缓慢分解，历时数百年。一个塑料瓶需要450年才能消失。垃圾桶不是终点，扔之前，先想一想。
Can Sound Be Dangerous?
声音会伤人吗？
Sound is just waves moving through air, but some waves are extremely powerful. Very loud sounds — over 150 decibels — can burst your eardrums instantly. A jet engine reaches about 140 decibels. Scientists have also discovered "infrasound": sounds too low for humans to hear. Some animals use infrasound to communicate across hundreds of kilometres. Large waterfalls and storms produce infrasound too. Scientists believe infrasound can make people feel uneasy or even frightened without knowing why. Sound is everywhere — and not always friendly.
声音只是在空气中传播的波，但有些波极其强大。非常响的声音——超过150分贝——能瞬间震破耳膜。喷气发动机大约能达到140分贝。科学家还发现了“次声波”：低到人耳无法听见的声音。一些动物用次声波进行跨越数百公里的交流。大型瀑布和风暴也会产生次声波。科学家认为，次声波能让人莫名地感到不安甚至恐惧。声音无处不在——但并不总是友好的。
China's High-Speed Secret
中国高铁的秘密
China has the world's longest high-speed railway network — over 45,000 kilometres. A train from Beijing to Shanghai, once a 12-hour journey, now takes just four hours. How does it work? The tracks are built on raised platforms to avoid bumps. The trains are shaped like dolphins to cut through air smoothly. Special sensors detect earthquakes and stop trains automatically. Every detail is engineered for safety and speed. China did not just build railways — it redefined what a railway could be.
中国拥有世界上最长的高铁网络——超过4.5万公里。从北京到上海，曾经需要12个小时，现在只需4个小时。它是怎么做到的？轨道建在高架平台上以避免颠簸；列车设计成海豚形状以顺畅穿越空气；特殊传感器能检测地震并自动停车。每一个细节都经过精心设计，以保障安全与速度。中国不只是建了铁路——它重新定义了铁路的可能性。
The World's Most Helpful Cats
世界上最有用的猫
Cats and libraries have a long history together. In medieval Europe, cats lived in monasteries to protect ancient books from mice. Today, many libraries around the world still have official "library cats." The most famous was Dewey, who lived in a small-town library in Iowa, USA for 19 years. He greeted every visitor, cheered up lonely readers, and even appeared in a best-selling book. Libraries store human knowledge. Cats, it seems, store something warmer — comfort.
猫与图书馆有着悠久的渊源。在中世纪的欧洲，猫生活在修道院里，保护古老的书籍不被老鼠啃咬。如今，世界上许多图书馆仍有官方认定的“馆猫”。其中最著名的是杜威，它在美国爱荷华州一个小镇的图书馆里生活了19年。它迎接每一位来访者，给孤独的读者带来安慰，甚至出现在一本畅销书里。图书馆储存人类的知识，而猫，似乎储存着更温暖的东西——慰藉。
Colours That Change How You Feel
颜色会影响你的心情
Did you know that colour can change how you feel — even how fast your heart beats? Red makes people feel excited and hungry, which is why fast-food restaurants use it. Blue makes people feel calm and focused, so many offices and schools paint their walls blue. Yellow brings energy and happiness but can cause anxiety if overused. Green reminds us of nature and helps reduce stress. Your bedroom colour might be affecting your sleep right now. Colours are silent, but very powerful.
你知道颜色能改变你的感受——甚至改变你的心跳速率吗？红色让人感到兴奋和饥饿，这就是为什么快餐店常用红色。蓝色让人感到平静和专注，因此许多办公室和学校把墙壁涂成蓝色。黄色带来活力和快乐，但过多使用会引发焦虑。绿色让人想到自然，有助于减轻压力。你卧室的颜色，也许此刻正在影响你的睡眠。颜色无声无息，却力量强大。
Why Does Time Fly When You're Having Fun?
为什么开心的时候时间过得特别快？
One hour of maths feels like three. One hour of gaming feels like ten minutes. Why? It is all in the brain. When we are bored or scared, our brains record every small detail — time feels longer. When we are happy or focused, the brain records less — time feels shorter. As we grow older, each year becomes a smaller fraction of our whole life, so years seem to speed up. Time is not just on the clock. It lives in your mind.
一节数学课感觉有三个小时那么长，而玩游戏的一个小时感觉只有十分钟。为什么？这都是大脑在作怪。当我们感到无聊或恐惧时，大脑会记录每一个细小的细节——时间感觉更长。当我们快乐或专注时，大脑记录的信息更少——时间感觉更短。随着年龄增长，每一年在我们整个生命中所占的比例越来越小，所以岁月似乎越来越快。时间不只存在于钟表上，它住在你的大脑里。