?An intrepid undergrad led the way to understanding the physics of snapping strands of spaghetti.一個(gè)勇于探索的大學(xué)生,開(kāi)辟了一條求解意面的斷裂原理的新思路。
? 播音\撰文:卡倫·霍普金(Karen Hopkin) 翻譯:陳美娟
? Physicists concern themselves with problems that are profound. The?origins of the universe, the?nature of time, the?composition of matter. And then, there’s spaghetti. A pasta problem has perplexed physicists as celebrated as?Richard Feynman, and has even been awarded an Ig Nobel prize. At issue: 物理學(xué)家一般會(huì)關(guān)注深刻的命題。例如宇宙的起源,時(shí)間的本質(zhì),物質(zhì)的構(gòu)成,以及,意面!“意面問(wèn)題”困住了一群像理查德·費(fèi)曼(Richard Feynman)一樣的著的名物理學(xué)家,該領(lǐng)域的研究成果甚至被評(píng)過(guò)搞笑諾貝爾獎(jiǎng)(IgNoble Price)。 “Why?spaghetti?doesn’t break into two pieces. Why it breaks into three pieces or more.” “為什么一根意面不能斷成兩段。為什么它只能斷成三段以上?!?/span> Ronald Heisser, now a grad student at Cornell, decided to explore the misbehavior of spaghetti for an undergraduate math course he took at MIT. 羅納德·海瑟(Ronald Heisser)現(xiàn)在是康奈爾大學(xué)的一名研究生,他在麻省理工大學(xué)的一次本科數(shù)學(xué)上并決定研究意面這種“不聽(tīng)話”的表現(xiàn)。 Now, you may never have noticed it, but it’s nearly impossible to break a single, dry piece of spaghetti in half. Feynman allegedly noodled with the puzzle. And Heisser became similarly possessed. 你可能永遠(yuǎn)不會(huì)注意到這個(gè)現(xiàn)象,不過(guò)想要把一根干意面條折成一半幾乎是不可能的。據(jù)說(shuō)費(fèi)曼一直糾結(jié)著這個(gè)謎,而海瑟也經(jīng)歷過(guò)相似的過(guò)程。 “I’m a little bit of a contrarian person. So I thought it would be fun to try and break it into two. ‘Cause no one said you couldn’t do that. They just said why it doesn’t break into two.” “我是一個(gè)有點(diǎn)叛逆的人。我想,試著把面條折成兩段會(huì)很好玩。因?yàn)闆](méi)人說(shuō)過(guò)你不能把意面折成兩段。他們只是說(shuō)為什么意面折不成兩段?!?/span> In fact, the French researchers who were awarded the Ig Nobel prize in 2006 found that when spaghetti is bent evenly from both ends it will crack near the center, where the stick is most curved. But this initial break sets up a vibrational wave that quickly fractures the rod further. So you get multiple fragments. 事實(shí)上,2006年獲得“搞笑諾貝爾獎(jiǎng)”的法國(guó)研究者發(fā)現(xiàn),將意面從距離兩端點(diǎn)相同的位置彎折的時(shí)候裂口離中心很近,此處面條達(dá)到最彎。但是折斷之后引發(fā)的振動(dòng)波迅速讓斷裂加劇。這就是最后你得到不止兩截面條的原因。 What Heisser wondered was whether he could somehow get around this vibrational “snapback” effect. And he found you have to do the twist.?Heisser built a device for torquing his pasta with precision and he observed the resulting fragmentation with a high-speed camera. He discovered that introducing a twist of around 360 degrees to the long strand allowed him to produce the desired single pair of pasta pieces. 海瑟想知道他是否能設(shè)法繞開(kāi)這種震動(dòng)“反彈”效應(yīng)。而他發(fā)現(xiàn)必須要制造扭曲的狀態(tài)才可以。海瑟制造了一個(gè)裝置用來(lái)精確地扭轉(zhuǎn)他的意大利面,并用高速攝影機(jī)觀察由此產(chǎn)生的碎片。他發(fā)現(xiàn)當(dāng)一長(zhǎng)條意面扭轉(zhuǎn)到360度時(shí)就能制造出他想要的單對(duì)意面段。 That’s where?Vishal Patil, a grad student in mathematics at MIT, comes in: 這就是另一個(gè)麻省理工數(shù)學(xué)專業(yè)研究生維薩爾·帕蒂爾(Vishal Patil)加入的原因: “So I first heard about this spaghetti problem from coauthors Ronald Heisser and Professor?J?rn Dunkel?when I first arrived at MIT…and after hearing about this problem, I became interested in developing mathematical models for the fracture of this elastic rod. And in particular, to see if using this model you could find out ways to control the fracture in the rod.” “當(dāng)我來(lái)到麻省第一次從合著者羅納德·海瑟和約翰恩·鄧克爾(J?rn Dunkel)教授那里聽(tīng)說(shuō)這個(gè)意面問(wèn)題的時(shí)候,我就對(duì)建造這種有彈性面條折斷時(shí)的數(shù)學(xué)模型非常感興趣,尤其是想利用這種模型找到控制折斷它的方法。” Controlling fractures is a big issue in materials science and could have applications in everything from the design of highways and bridges to the engineering of nanotubes. 在材料科學(xué)上,控制折斷反應(yīng)是一個(gè)大的課題,它有從高速公路設(shè)計(jì)到納米管的各類工程上的廣泛應(yīng)用。 Patil’s modeling showed that twisting the spaghetti dampens the snapback effect. That’s because once the twisted stick is broken, it will try to unwind. This rapid unwinding creates a “twisting wave” that basically blocks the vibrational snapback wave, leaving the spaghetti in two clean pieces. The work is served up in the?Proceedings of the National Academy of Sciences. [Ronald H. Heisser et al.,?Controlling fracture cascades through twisting and quenching] 帕蒂爾的模型顯示,扭轉(zhuǎn)意面能抑制回彈反應(yīng)。這是因?yàn)橐坏┍慌まD(zhuǎn)的面條破裂,它就會(huì)舒展開(kāi)。這種迅速的舒展反應(yīng)制造了能阻斷振動(dòng)回彈波的“扭轉(zhuǎn)波”,因此讓意面利落地?cái)喑蓛山?。這項(xiàng)研究發(fā)表在《國(guó)家科學(xué)學(xué)報(bào)》上。 VP: “Although the project was a bit of fun I think it’s quite nice when you can find interesting physics and maths lurking behind everyday, mundane objects.” 維薩爾·帕蒂爾說(shuō):“盡管這個(gè)研究項(xiàng)目聽(tīng)著有點(diǎn)不正經(jīng),我覺(jué)得能從每天的日常生活中發(fā)現(xiàn)隱藏的物理和數(shù)學(xué)現(xiàn)象還是很棒的?!?/span>