Wednesday, March 04, 2009

What does it all mean?

[This is the pre-edited version of my latest Muse for Nature News.]

Science depends on clear terms and definitions – but the world doesn’t always oblige.

What’s wrong with this statement: ‘The acceleration of an object is proportional to the force acting on it.’ You might think no one could object to this expression of Newton’s second law. But Nobel laureate physicist Frank Wilczek does. This law, he admits, ‘is the soul of classical mechanics.’ But he adds that, ‘like other souls, it is insubstantial’ [1].

Bertrand Russell went further. In 1925 he called for the abolition of the concept of force in physics, and claimed that if people learnt to do without it, this ‘would alter not only their physical imagination, but probably also their morals and politics.’ [2]

That seems an awfully heavy burden for a word that most scientists will use unquestioningly. Wilczek does not go as far as Russell, but he agrees that the concept of ‘force’ acquires meaning only through convention – through the culture of physics – and not because it refers to anything objective. He suspects that only ‘intellectual inertia’ accounts for its continued use.

It’s a disconcerting reminder that scientific terminology, supposed to be so precise and robust, is often much more mutable and ambiguous than we think – which makes it prone to misuse, abuse and confusion [3,4]. But why should that be so?

There are, broadly speaking, several potential problems with words in science. Let’s take each in turn.

Misuse

Some scientific words are simply misapplied, often because their definition is ignored in favour of something less precise. Can’t we just stamp out such transgressions? Not necessarily, for science can’t expect to evade the transformations that any language undergoes through changing conventions of usage. When misuse becomes endemic, we must sometimes accept that a word’s definition has changed de facto. ‘Fertility’ now often connotes birth rate, not just in general culture but among demographers. That is simply not its dictionary meaning, but is it now futile to argue against it? Similarly, it is now routine to speak of protein molecules undergoing phase transitions, which they cannot in the strict sense since phase transitions are only defined in systems that can be extrapolated to infinite size. Here, however, the implication is clear, and inventing a new term is arguably unhelpful.

Perhaps word misuse matters less when it simply alters or broadens meaning – the widespread use of ‘momentarily’ to indicate ‘in a moment’ is wrong and ugly, but it is scarcely disastrous to tolerate it. It’s more problematic when misuse threatens to traduce logic, as for example when the new meaning attached to ‘fertility’ allows the existence of fertile people who have zero fertility.

Everyday words used in science

In 1911 the geologist John W. Gregory, chairman of the British Association for the Advancement of Science, warned of the dangers of appropriating everyday words into science [5]. Worms, elements, rocks – all, he suggested, run risks of securing ‘specious simplicity at the price of subsequent confusion.’ Interestingly, Gregory also worried about the differing uses of ‘metal’ in chemistry and geology; what would he have said, one wonders, about the redefinition later placed on the term by astronomers (any element heavier than helium) which, whatever the historical justification, shows a deplorable lack of self-discipline. Such Humpty Dumpty-style assertions that a familiar word can mean whatever one chooses are more characteristic of the excesses of postmodern philosophy that scientists often lament.

There are hazards in trying to assign new and precise meanings to old and imprecise terms. Experts in nonlinear dynamics can scarcely complain about misuses of ‘chaos’ when it already had several perfectly good meanings before they came along. On the other hand, by either refusing or failing to provide a definition of everyday words that they appropriate – ‘life’ being a prime victim here – scientists risk breeding confusion. In this regard, science can’t win.

Fuzzy boundaries

When scientific words become fashionable, haziness is an exploitable commodity. One begins to suspect there are few areas of science that cannot be portrayed as complexity or nanotechnology. It recently became popular to assert a fractal nature in almost any convoluted shape, until some researchers eventually began to balk at the term being awarded to structures (like ferns) whose self-similarity barely extends beyond a couple of levels of magnification [6].

Heuristic value

The reasons for Wilczek’s scepticism about force are too subtle to describe here, but they don’t leave him calling for its abolition. He points out that it holds meaning because it fits our intuitions – we feel forces and see their effects, even if we don’t strictly need them theoretically. In short, the concept of force is easy to work with: it has heuristic value.

Science is full of concepts that lack sharp definition or even logic but which help us understand the world. Genes are another. The way things are going, it is possible that one day the notion of a gene may create more confusion than enlightenment [7], but at present it doesn’t seem feasible to understand heredity or evolution without their aid – and there’s nothing better yet on offer.

Chemists have recently got themselves into a funk over the concept of oxidation state [8,9]. Some say it is a meaningless measure of an atom’s character; but the fact remains that oxidation states bring into focus a welter of chemical facts, from balancing equations to understanding chemical colour and crystal structure. One could argue that ‘wrong’ ideas that nonetheless systematize observations are harmful only when they refuse to give way to better ones (pace Aristotelian physics and phlogiston), while teaching science is a matter of finding useful (as opposed to ‘true’) hierarchies of knowledge that organize natural phenomena.

The world doesn’t fit into boxes

We’ve known that for a long time: race and species are terms guaranteed to make biologists groan. Now astronomers fare little better, as the furore over the meaning of ‘planet’ illustrated [10] – a classic example of the tension between word use sanctioned by definition or by convention.

The same applies to ‘meteorite’. According to one, perfectly logical, definition of a meteorite, it is not possible for a meteorite ever to strike the Earth (since it becomes one only after having done so). Certainly, the common rule of thumb that meteors are extraterrestrial bodies that enter the atmosphere but don’t hit the surface, while meteorites do, is not one that planetary scientists will endorse. There is no apparent consensus about what they will endorse, which seems to be a result of trying to define processes on the basis of the objects they involve.

All of this suggests some possible rules of thumb for anyone contemplating a scientific neologism. Don’t invent a new word without really good reason (for example, don’t use it to patch over ignorance). Don’t neglect to check if one exists already (we don’t want both amphiphilic and amphipathic). Don’t assume you can put an old word to new use. Make the definition transparent, and think carefully about its boundaries. Oh, and try to make it easy to pronounce - not just in Cambridge but in Tokyo too.

References

1. Wilczek, F. Physics Today 57(10), 11-12 (2004).
2. Russell, B. The ABC of Relativity, 5th edn, p.135 (Routledge, London, 1997).
3. Nature 455, 1023-1028 (2008).
4. Parsons, J. & Wand, Y., Nature 455, 1040-1041 (2008).
5. Gregory, J. W. Nature 87, 538-541 (1911).
6. Avnir, D., Biham, O., Lidar, D. & Malcar, O. Science 279, 39-40 (1998).
7. Pearson, H. Nature 441, 398-401 (2006).
8. Raebinger, H., Lany, S. & Zunger, A. Nature 453, 763 (2008).
9. Jansen, M. & Wedig, U. Angew. Chem. Int. Ed. doi:10.1002/anie.200803605.
10. Giles, J. Nature 437, 456-457 (2005).

4 comments:

Pat said...

This is a nice overview of the fluidity (everyday example!) of terms we often assume to be, or use as, static definitions.

It seems that the need for fixed definitions would be at home in mathematics, and perhaps the concerns reflect a desire to "ground" our definitions in a similar basis.

Adrian said...

In my opinion, those leads that you propose should suffice but I still encourage the use of neologisms and new words in order to enclose a concept or phenomenon. We must not think that adding up new words creates confusion, rather, we should make new "words" in which the meaning is tightly bound to the iconic representation itself (such as the "cepstrum" or Hooke's "ceiiinossstuv") If we dared to make new meanings by tinkering with the box (language) we wouldn't be arguing about meanings and ambiguities with other fields. I guess someday creativity and dominion of language will become commonplace in science again someday. Someday, we'll dare to have the periodic table inertia again.

uhfdf said...

歐美a免費線上看,熊貓貼圖區,ec成人,聊天室080,aaa片免費看短片,dodo豆豆聊天室,一對一電話視訊聊天,自拍圖片集,走光露點,123456免費電影,本土自拍,美女裸體寫真,影片轉檔程式,成人視訊聊天,貼圖俱樂部,辣妹自拍影片,自拍電影免費下載,電話辣妹視訊,情色自拍貼圖,卡通做愛影片下載,日本辣妹自拍全裸,美女裸體模特兒,showlive影音聊天網,日本美女寫真,色情網,台灣自拍貼圖,情色貼圖貼片,百分百成人圖片 ,情色網站,a片網站,ukiss聊天室,卡通成人網,3級女星寫真,080 苗栗人聊天室,成人情色小說,免費成人片觀賞,

傑克論壇,維納斯成人用品,免費漫畫,內衣廣告美女,免費成人影城,a漫,國中女孩寫真自拍照片,ut男同志聊天室,女優,網友自拍,aa片免費看影片,玩美女人短片試看片,草莓論壇,kiss911貼圖片區,免費電影,免費成人,歐美 性感 美女 桌布,視訊交友高雄網,工藤靜香寫真集,金瓶梅免費影片,成人圖片 ,女明星裸體寫真,台灣處女貼圖貼片區,成人小遊戲,布蘭妮貼圖片區,美女視訊聊天,免費情色卡通短片,免費av18禁影片,小高聊天室,小老鼠論壇,免費a長片線上看,真愛love777聊天室,聊天ukiss,情色自拍貼圖,寵物女孩自拍網,免費a片下載,日本情色寫真,美女內衣秀,色情網,

liwo said...

av自拍,臺灣18歲成人免費,avon,正妹強力牆,免費線上成人影片,免費遊戲,a片貼圖,正妹圖片,3d美女圖,杜蕾斯免費a片,蓬萊仙山寫真集,a片網站,哈拉網路成人區,sex女優王國,性感美女,自拍密錄館,18禁卡通,爽翻天成人網,go2av,網拍模特兒應徵,台灣18成人,制服美女,小老鼠成人,成人光碟,金瓶影片交流區,85cc免費影城,成人交友,蓬萊仙山寫真集,無碼,正妹強力牆,嘟嘟情色網,影片轉檔程式,免費成人片觀賞,拓網交友,松島楓免費影片,色美眉部落格,18成人avooo,美腿論壇,辣媽辣妹,露點寫真,哈雷聊天室,18禁影片,看a片,美女工廠,影音城論壇,美女影片,免費遊戲,免費算,小魔女貼影片,a片貼圖,美腿褲襪高跟鞋,av女優王國,觀月雛乃影片,性感美女,

女優王國,免費無碼a片,0800a片區,免費線上遊戲,無名正妹牆,成人圖片,寫真美女,av1688影音娛樂網,dodo豆豆聊天室,網拍模特兒,成人文學,免費試看a片,a片免費看,成人情色小說,美腿絲襪,影片下載,美女a片,人體寫真模特兒,熊貓成人貼,kiss情色,美女遊戲區,104 貼圖區,線上看,aaa片免費看影片,天堂情色,躺伯虎聊天室,洪爺情色網,kiss情色網,貼影區,雄貓貼圖,080苗栗人聊天室,都都成人站,尋夢園聊天室,a片線上觀看,無碼影片,情慾自拍,免費成人片,影音城論壇,情色成人,最新免費線上遊戲,a383影音城,美腿,色情寫真,xxx383成人視訊,視訊交友90739,av女優影片,