Tuesday, April 17, 2007

Tales of the expected

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

A recent claim of water on an extrasolar planet raises broader questions about how science news is reported.

“Scientists discover just what they expected” is not, for obvious reasons, a headline you see very often. But it could serve for probably a good half of the stories reported in the public media, and would certainly have been apt for the recent reports of water on a planet outside our solar system.

The story is this: astronomer Travis Barman of the Lowell Observatory in Flagstaff, Arizona, has claimed to find a fingerprint of water vapour in the light from a Sun-like star 150 light years away as it passes through the atmosphere of the star’s planet HD 209458b [T. Barman, Astrophys. J. in press (2007); see the paper here].

The claim is tentative and may be premature. But more to the point, at face value it confirms precisely what was expected for HD 209458b. Earlier observations of this Jupiter-sized planet had failed to see signs of water – but if it were truly absent, something would be seriously wrong with our understanding of planetary formation.

The potential interest of the story is that water is widely considered by planetary scientists to be the prerequisite for life. But if it’s necessary, it is almost certainly not sufficient. There is water on most of the other planets in our solar system, as well as several of their moons and indeed in the atmosphere of the Sun itself. But as yet there is no of sign of life on any of them.

The most significant rider is that to support life as we know it, water must be in the liquid state, not ice or vapour. That may be the case on Jupiter’s moons Europa and Callisto, as it surely once was (and may still be, sporadically) on Mars. But in fact we don’t even know for sure that water is a necessary condition for life: there is no reason to think, apart from our unique experience of terrestrial life, that other liquid solvents could not sustain living systems.

All of this makes Barman’s discovery – which he reported with such impeccable restraint that it could easily have gone unnoticed – intriguing, but very modestly so. Yet it has been presented as revelatory. “There may be water beyond our solar system after all”, exclaimed the New York Times. “First sign of water found on an alien world”, said New Scientist (nice to know that, in defiance of interplanetary xenophobia, Martians are no longer aliens).

As science writers are dismayingly prone to saying sniffily “oh, we knew that already”, I’m hesitant to make too much of this. It’s tricky to maintain a perspective on science stories without killing their excitement. But the plain fact is that there is water in the universe almost everywhere we look – certainly, it is a major component of the vast molecular clouds from which stars and planets condense.

And so it should be, given that its component atoms hydrogen and oxygen are respectively the most abundant and the third most common in the cosmos. Relatively speaking, ours is a ‘wet’ universe (though yes, liquid water is perhaps rather rare).

The truth is that scientists work awfully hard to verify what lazier types might be happy to take as proven. Few doubted that Arthur Eddington would see, in his observations of a solar eclipse in 1919, the bending of light predicted by Einstein’s theory of general relativity. But it would seem churlish in the extreme to begrudge the headlines that discovery generated.

Similarly, it would be unfair to suggest that we should greet the inevitable sighting of the Higgs boson (the so-called ‘God’ particle thought to give other particles their mass) with a shrug of the shoulders, once it turns up at the billion-dollar particle accelerator constructed at CERN in Geneva.

These painstaking experiments are conducted not so that their ‘success’ produces startling front-page news but because they test how well, or how poorly, we understand the universe. Both relativity and quantum mechanics emerged partly out of a failure to find the expected.

In the end, the interest of science news so often resides not in discovery but in context: not in what the experiment found, but in why we looked. Barman’s result, if true, tells us nothing we did not know before, except that we did not know it. Which is why it is still worth knowing.


Anonymous 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,

Anonymous said...


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,