Wouldn't it be great if we could be invisible? Ha, right? I mean, we could spy on people without being noticed and do whatever we want without being held responsible. Now, magicians have figured out how to utilize full-sized mirrors to bend light in order to create disappearing illusions. Scientists have created metamaterials to guide rays of light around tiny, two-dimensional objects. Cameras can also film what is behind you and project the image so you appear invisible from the front. However, none of these options can make an object as large as a person appear invisible for all angles and distances while its moving. But if you are truly invisible, as in from within, here are a few problems you may not have thought about before. To move around undetected by other people, you would have to be totally naked. Even if it's freezing outside! You can't carry anything, including your wallet and keys, otherwise people would just see your wallet and keys floating around. Drivers and people on the street can't see you either, therefore they can and will run into you at some point. Oh, and you better not wear any perfume or make any noise breathing, otherwise they'll know you're there. And, just because you start off invisible, doesn't mean you'll stay that way. What if someone accidentally spills scolding hot coffee on you? And what if it rains? But if you think only liquid can make you visible, you're wrong. Dust consists of dead skin cells from humans, soil particles, and fibers from clothes made from cotton and other materials. Dust sticks to the moisture on our skin when we sweat and the tiny hairs on our skin when we are dry. So, even if you are invisible, dust would still land on every part of you. We usually don't notice the dust on our skin because we can't see a thin layer of dust on top of our skin color. But, if you're invisible, people would see a human-shaped blob of dust walking around with extremely dirty soles. Gross! What do you think the world looks like if you are invisible? Well, the answer is nothing. The reason you can't see in the dark is because there is no light. To see an apple, light has to hit the apple and return it to your eyes. Then, the retinas in your eyes catch the light reflection for your brain to interpret into the image of an apple. If you're invisible, then, by definition, light would travel through you or around you instead of bouncing off you for people to see. But that means that retinas in your eyes are not catching the light, either. Therefore, your brain has nothing to interpret into an image. Can you see your reflection without a mirror to stop the light? No. So, when you can't be seen by others, you also cannot see. Ouch! Now, have you given any thought as of whether the invisibility is permanent? If it is, how can you receive medical treatment from a doctor if you're injured? The doctor wouldn't know where to apply ointments or bandages because they cannot access your injury. For that matter, you can't see it either. I mean, what if you have an illness or an infection? How can the doctor diagnose you without being able to see the color change or inflammation? And what if everyone is permanently invisible? Well, think about how boring the world would be without seeing people on the streets, on TV, or at home on your computer like right now. It's lonely being invisible. Now, which superpower physics lesson will you explore next? Shifting body size and content, super speed, flight, super strength, immortality, and invisibility.
如果我們能隱形 那不是超棒的嗎? 哈,不是嗎? 我們偷窺別人不會被發現 也可以為所欲為 卻不用負什麼責任 現在,魔術師已經知道 如何利用全身鏡折射光線 製造出隱形的假象 科學家製造出超材料 能引導光線 繞過微細的 2D 物體 照相機也可以拍攝你背後的景象 投射出影像 如此一來,你就像隱形了一樣 然而,這些方式 都沒辦法讓一個真人大小的物體 在移動的情況下 從所有角度和距離看 都保持隱形 即使你真的做到 從內到外都隱形 這裡還有一些問題 你之前可能沒列入考慮 要在別人無法察覺的情況下行動 你必須完全裸體 就算外面天寒地凍 你也不能攜帶任何東西 連你的錢包和鑰匙都不能帶 否則人們就會只看到 你的錢包和鑰匙在空中飄浮移動 路上的駕駛和行人也看不到你 他們可能會直接撞上你 喔,你最好別用任何香水 呼吸也不能出聲 否則人們會注意到你的存在 而且就算你真的開始隱形 也不表示你可以一直如此 假使有人不小心 把熱咖啡潑到你身上? 又或是下起雨了? 如果你以為只有液體會讓你現形 那你可就錯了 灰塵包含人體代謝的皮膚細胞 土壤顆粒 衣服上的棉絮纖維 以及其它材質 我們流汗時 灰塵會附著在潮濕的皮膚上 而乾燥時灰塵會附在毛髮上 所以就算隱形了 灰塵還是會落在你全身上下 我們通常不會注意到皮膚上的灰塵 是因為我們有膚色為底 所以看不到有薄薄的灰塵覆蓋 但如果隱形了 大家就會看到一個覆滿灰塵的人型 到處走動還留下超髒的腳印 太噁心了! 你有沒有想過當你隱形的時候 這世界看起來是什麼樣子? 答案是什麼都沒有 你在黑暗中看不到東西 是因為沒有光線 你要能看到一個蘋果 得要有光線照到這個蘋果 再回到你的眼睛 然後你眼睛裡的視網膜 會將這光線反射到你的腦中 轉譯為一個蘋果的影像 如果你隱形了 在這定義下 光線會穿越你,或是繞過你 並不會有任何反射讓人們看到你 但這代表你的視網膜 也無法捕捉到任何光線 所以你的腦不會收到任何訊息 能被轉譯為影像 如果沒有鏡子阻擋光線前進 你能看到你自己的影像嗎? 不能 所以當你不能被其他人看到時 你自己也看不到 哎喲! 你有想過 要不要永遠隱形嗎? 如果永遠隱形,哪天你受傷了 醫生要怎麼為你治療? 醫生無法知道 要在哪裡塗藥膏或是上繃帶 因為他們看不到你的傷口 而且連你自己也看不到啊 如果你生病或是感染了 醫生看不到顏色的改變或是發炎的情況 要怎麼幫你診斷? 假如每個人都永遠隱形了呢? 你想想這世界會有多無趣 看不到任何人在街上 在電視裡 或者是在家裡的電腦上 就像現在一樣 隱形是很寂寞的 接下來,你想探索 哪個超能力物理學課程? 改變身體大小和成分? 超高速? 飛行能力? 超級大力士? 永生不死? 或者 隱形力