2015年10月29日 星期四

Blockchain technology


Block chain (database) - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Block_chain_(database)
block chain or blockchain is a distributed database that maintains a continuously growing list of data records that are hardened against tampering and revision ...

Block chain - Bitcoin Wiki

https://en.bitcoin.it/wiki/Block_chain
block chain is a transaction database shared by all nodes participating in a system based on the Bitcoin protocol. A full copy of a currency's block chain ...
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Blockchain technology is mundane and unsexy, but has the potential to transform how people and businesses co-operate

The technology behind bitcoin could transform how the economy works
ECON.ST

Scientist Can Put Your Immune System Into A Mouse's Body

She's a Columbia immunologist!
“I can take your immune system and transplant it into a mouse that I’ve genetically engineered to have no immune system of it’s own, so that I can model the genetics of your immune system and find immunoregulatory defects that will determine how you are going to respond to the cellular therapy needed to treat your disease.”

We caught up with Nichole Danzi to talk about her work on autoimmunity.
HUFFINGTONPOST.COM

2015年10月27日 星期二

Robert Langer, Jr.

"The discoveries that I made went against conventional wisdom. I just believed in it, so I kept working on it": The multi award-winning scientist whose work may have helped 2 billion people worldwide.

World renowned scientist, Dr Robert Langer, on how 'engineering can…
BBC.IN


羅伯特·薩母耳·蘭格二世英語Robert Samuel Langer, Jr.,1948年8月29日),生於美國紐約州奧爾巴尼,生物工程學者,是麻省理工學院(MIT)的戴維·H·科克學院教授(MIT一共有14位學院教授,學院教授是MIT教授所能獲得的最高榮譽)。蘭格教授發表了超過1175篇論文。他還擁有超過800個專利(包括正在審核和已經通過的)。這些專利授權給了超過250個製藥、化學、生物技術和醫學儀器公司。蘭格教授是迄今被引用次數最多的工程學家。.....

蘭格教授是生物工程學領域的著名學者,尤其以對靶向藥物輸送系統和組織工程學的研究而知名。蘭格在麻省理工的實驗室是世界最大的生物醫學工程實驗室,年度經費超過$1000萬,有超過100名研究人員。[2]

Langer is recognized as the most cited engineer in history.[3] Langer's research laboratory at MIT is the largest biomedical engineering lab in the world, maintaining over $10 million in annual grants and over 100 researchers.[5]Langer is also currently[when?] on the board of directors at Bind Therapeutics and Ocata Therapeutics.[6] In 2015, Langer was awarded the Queen Elizabeth Prize for Engineering, the most influential prize in the world for engineering.[7][8][9]





2015年10月26日 星期一

Caltech Physicists Uncover Novel Phase of Matter

10/26/2015

Caltech Physicists Uncover Novel Phase of Matter

Finding could have implications for high-temperature superconductivity
A team of physicists led by Caltech's David Hsieh has discovered an unusual form of matter—not a conventional metal, insulator, or magnet, for example, but something entirely different. This phase, characterized by an unusual ordering of electrons, offers possibilities for new electronic device functionalities and could hold the solution to a long-standing mystery in condensed matter physics having to do with high-temperature superconductivity—the ability for some materials to conduct electricity without resistance, even at "high" temperatures approaching  –100 degrees Celsius.
"The discovery of this phase was completely unexpected and not based on any prior theoretical prediction," says Hsieh, an assistant professor of physics, who previously was on a team that discovered another form of matter called a topological insulator. "The whole field of electronic materials is driven by the discovery of new phases, which provide the playgrounds in which to search for new macroscopic physical properties."
Hsieh and his colleagues describe their findings in the November issue of Nature Physics, and the paper is now available online. Liuyan Zhao, a postdoctoral scholar in Hsieh's group, is lead author on the paper.
The physicists made the discovery while testing a laser-based measurement technique that they recently developed to look for what is called multipolar order. To understand multipolar order, first consider a crystal with electrons moving around throughout its interior. Under certain conditions, it can be energetically favorable for these electrical charges to pile up in a regular, repeating fashion inside the crystal, forming what is called a charge-ordered phase. The building block of this type of order, namely charge, is simply a scalar quantity—that is, it can be described by just a numerical value, or magnitude.
In addition to charge, electrons also have a degree of freedom known as spin. When spins line up parallel to each other (in a crystal, for example), they form a ferromagnet—the type of magnet you might use on your refrigerator and that is used in the strip on your credit card. Because spin has both a magnitude and a direction, a spin-ordered phase is described by a vector.
Over the last several decades, physicists have developed sophisticated techniques to look for both of these types of phases. But what if the electrons in a material are not ordered in one of those ways? In other words, what if the order were described not by a scalar or vector but by something with more dimensionality, like a matrix? This could happen, for example, if the building block of the ordered phase was a pair of oppositely pointing spins—one pointing north and one pointing south—described by what is known as a magnetic quadrupole. Such examples of multipolar-ordered phases of matter are difficult to detect using traditional experimental probes.
As it turns out, the new phase that the Hsieh group identified is precisely this type of multipolar order.  
To detect multipolar order, Hsieh's group utilized an effect called optical harmonic generation, which is exhibited by all solids but is usually extremely weak. Typically, when you look at an object illuminated by a single frequency of light, all of the light that you see reflected from the object is at that frequency. When you shine a red laser pointer at a wall, for example, your eye detects red light. However, for all materials, there is a tiny amount of light bouncing off at integer multiples of the incoming frequency. So with the red laser pointer, there will also be some blue light bouncing off of the wall. You just do not see it because it is such a small percentage of the total light. These multiples are called optical harmonics.
The Hsieh group's experiment exploited the fact that changes in the symmetry of a crystal will affect the strength of each harmonic differently. Since the emergence of multipolar ordering changes the symmetry of the crystal in a very specific way—a way that can be largely invisible to conventional probes—their idea was that the optical harmonic response of a crystal could serve as a fingerprint of multipolar order.   
"We found that light reflected at the second harmonic frequency revealed a set of symmetries completely different from those of the known crystal structure, whereas this effect was completely absent for light reflected at the fundamental frequency," says Hsieh. "This is a very clear fingerprint of a specific type of multipolar order."
The specific compound that the researchers studied was strontium-iridium oxide (Sr2IrO4), a member of the class of synthetic compounds broadly known as iridates. Over the past few years, there has been a lot of interest in Sr2IrOowing to certain features it shares with copper-oxide-based compounds, or cuprates. Cuprates are the only family of materials known to exhibit superconductivity at high temperatures—exceeding 100 Kelvin (–173 degrees Celsius). Structurally, iridates and cuprates are very similar. And like the cuprates, iridates are electrically insulating antiferromagnets that become increasingly metallic as electrons are added to or removed from them through a process called chemical doping. A high enough level of doping will transform cuprates into high-temperature superconductors, and as cuprates evolve from being insulators to superconductors, they first transition through a mysterious phase known as the pseudogap, where an additional amount of energy is required to strip electrons out of the material. For decades, scientists have debated the origin of the pseudogap and its relationship to superconductivity—whether it is a necessary precursor to superconductivity or a competing phase with a distinct set of symmetry properties. If that relationship were better understood, scientists believe, it might be possible to develop materials that superconduct at temperatures approaching room temperature.
Recently, a pseudogap phase also has been observed in Sr2IrO4—and Hsieh's group has found that the multipolar order they have identified exists over a doping and temperature window where the pseudogap is present. The researchers are still investigating whether the two overlap exactly, but Hsieh says the work suggests a connection between multipolar order and pseudogap phenomena.
"There is also very recent work by other groups showing signatures of superconductivity in Sr2IrOof the same variety as that found in cuprates," he says. "Given the highly similar phenomenology of the iridates and cuprates, perhaps iridates will help us resolve some of the longstanding debates about the relationship between the pseudogap and high-temperature superconductivity."
Hsieh says the finding emphasizes the importance of developing new tools to try to uncover new phenomena. "This was really enabled by a simultaneous technique advancement," he says.
Furthermore, he adds, these multipolar orders might exist in many more materials. "Sr2IrO4 is the first thing we looked at, so these orders could very well be lurking in other materials as well, and that's exactly what we are pursuing next."
Additional Caltech authors on the paper, "Evidence of an odd-parity hidden order in a spin–orbit coupled correlated iridate," are Darius H. Torchinsky, Hao Chu, and Vsevolod Ivanov. Ron Lifshitz of Tel Aviv University, Rebecca Flint of Iowa State University, and Tongfei Qi and Gang Cao of the University of Kentucky are also coauthors. The work was supported by funding from the Army Research Office, the National Science Foundation (NSF), and the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support from the Gordon and Betty Moore Foundation.
Written by Kimm Fesenmaier
- See more at: http://www.caltech.edu/news/caltech-physicists-uncover-novel-phase-matter-48573#sthash.DcK42pEh.dpuf




California Institute of Technology - Caltech
"The discovery of this phase was completely unexpected and not based on any prior theoretical prediction. The whole field of electronic materials is driven by the discovery of new phases, which provide the playgrounds in which to search for new macroscopic physical properties."—David Hsieh, assistant professor of physics
Artist's rendition of spatially segregated domains of multipolar order in the Sr2IrO4 crystal. The orientation of the multipolar order in each domain is depicted by the multi-lobed object.
Credit: Liuyan Zhao
- See more at: http://www.caltech.edu/news/caltech-physicists-uncover-novel-phase-matter-48573#sthash.DcK42pEh.dpuf


It is not a conventional metal, insulator, or magnet. It is something entirely…
CALTECH.EDU

高富帥小鮮肉假科學: 叫聲最低沉響亮的公吼猴;男性身高

蘋論:高富帥小鮮肉

這兩天有兩則新聞十分有趣,說明了演化還是主宰我們行為的源頭,誰都擺脫不了演化對我們生命的主宰角色。
上周六,《紐約時報》報導英、美與奧地利科學家聯合發表的最新研究指出,嗓音低沉的男性擁有較多的性伴侶。他們以吼猴為例,叫聲最低沉響亮的公吼猴,身邊盡是成群的母猴,沒有其他公猴。但上帝很公平,有一好沒兩好,最受母猴歡迎的公猴的睪丸卻是公猴群中最小的,不知牠會不會遭到其他公猴們的訕笑?
科學家稱此現象為「演化的取捨」。研究者劍橋大學的鄧恩說,吼猴只能演化出低頻的吼聲或較大的睪丸,不可能兩者兼而有之。就像中國傳統的說法,富貴不可兼得一樣,否則叫其他人怎麼混?猶他大學教授說,該研究是第一份「吼聲與蛋蛋的論文」。
台灣研究團隊刊登在國際期刊《生物社會科學》上的研究指出,男性身高高人一等,把妹、娶妻真的有優勢,平均每高一公分,結婚的機率提高0.3個百分點,生子機率提高0.2個百分點;身高越高者,平均每周約會時間也越長,像是海拔170公分以下的男大生平均每周約會時間是3.93小時;而177公分以上的男大生平均每周約會5.63小時。海拔164公分的藝人黃子佼就說:「從我的案例來看,似乎屬實。」 

「三高男」最誘人

生物學家認為異性相吸的最初觸媒,第一是形貌,就是身高、長相、身材等外在條件;其次是聲音,第三是氣味。這三件滿足了,才講究財富、個性、地位、教育程度、幽默感等。台灣女人講究男性要三高──身材高、收入高、教育高,相當符合以上的研究。聲音是互相吸引的第二元素,與吼猴的條件差不多。 

矮男靠內涵取勝

在遠古時代,身材高有利於生存及覓食,很遠就可以看見火災及危險的來臨,而帶家人逃跑;狩獵、採集也是高個子強過矮個子,與高個子繁衍後代也可改良品種,生下高個子的兒女,這些都種下了女性喜歡高個子男性的意識與本能。現在流行姊姊的小鮮肉,也是高的較矮的吃香。
還好人類發展出精神層面的需求,矮的男性可以在這方面加強努力,像是智慧、能力、善良、體貼、學養、幽默、浪漫、品格等優點,如果加上財富,吸引異性的能力比平庸的高富帥鮮肉強得多了。 

2015年10月24日 星期六

The bizarre reactor that might save nuclear fusion

Ever heard of a stellarator? It might just crack the problem of nuclear fusion power.

Twisted Logic
ADAPTED FROM IPP BY C. BICKEL/ SCIENCE

Feature: The bizarre reactor that might save nuclear fusion

Daniel is a deputy news editor forScience.
If you’ve heard of fusion energy, you’ve probably heard of tokamaks. These doughnut-shaped devices are meant to cage ionized gases called plasmas in magnetic fields while heating them to the outlandish temperatures needed for hydrogen nuclei to fuse. Tokamaks are the workhorses of fusion—solid, symmetrical, and relatively straightforward to engineer—but progress with them has been plodding.
Now, tokamaks’ rebellious cousin is stepping out of the shadows. In a gleaming research lab in Germany’s northeastern corner, researchers are preparing to switch on a fusion device called a stellarator, the largest ever built. The €1 billion machine, known as Wendelstein 7-X (W7-X), appears now as a 16-meter-wide ring of gleaming metal bristling with devices of all shapes and sizes, innumerable cables trailing off to unknown destinations, and technicians tinkering with it here and there. It looks a bit like Han Solo’s Millennium Falcon, towed in for repairs after a run-in with the Imperial fleet. Inside are 50 6-tonne magnet coils, strangely twisted as if trampled by an angry giant.
Although stellarators are similar in principle to tokamaks, they have long been dark horses in fusion energy research because tokamaks are better at keeping gas trapped and holding on to the heat needed to keep reactions ticking along. But the Dali-esque devices have many attributes that could make them much better prospects for a commercial fusion power plant: Once started, stellarators naturally purr along in a steady state, and they don’t spawn the potentially metal-bending magnetic disruptions that plague tokamaks. Unfortunately, they are devilishly hard to build, making them perhaps even more prone to cost overruns and delays than other fusion projects. “No one imagined what it means” to build one, says Thomas Klinger, leader of the German effort.
W7-X could mark a turning point. The machine, housed at a branch of the Max Planck Institute for Plasma Physics (IPP) that Klinger directs, is awaiting regulatory approval for a startup in November. It is the first large-scale example of a new breed of supercomputer-designed stellarators that have had most of their containment problems computed out. If W7-X matches or beats the performance of a similarly sized tokamak, fusion researchers may have to reassess the future course of their field. “Tokamak people are waiting to see what happens. There’s an excitement around the world about W7-X,” says engineer David Anderson of the University of Wisconsin (UW), Madison.
Adapted from IPP by C. Bickel and A. Cuadra/Science
Wendelstein 7-X, the first large-scale optimized stellarator, took 1.1 million working hours to assemble, using one of the most complex engineering models ever devised, and must withstand huge temperature ranges and enormous forces.
Stellarators face the same challenge as all fusion devices: They must heat and hold on to a gas at more than 100 million degrees Celsius—seven times the temperature of the sun’s core. Such heat strips electrons from atoms, leaving a plasma of electrons and ions, and it makes the ions travel fast enough to overcome their mutual repulsion and fuse. But it also makes the gas impossible to contain in a normal vessel.

Instead, it is held in a magnetic cage. A current-carrying wire wound around a tube creates a straight magnetic field down the center of the tube that draws the plasma away from the walls. To keep particles from escaping at the ends, many early fusion researchers bent the tube into a doughnut-shaped ring, or torus, creating an endless track.
But the torus shape creates another problem: Because the windings of the wire are closer together inside the hole of the doughnut, the magnetic field is stronger there and weaker toward the doughnut’s outer rim. The imbalance causes particles to drift off course and hit the wall. The solution is to add a twist that forces particles through regions of high and low magnetic fields, so the effects of the two cancel each other out.
Stellarators impose the twist from outside. The first stellarator, invented by astro-physicist Lyman Spitzer at Princeton University in 1951, did it by bending the tube into a figure-eight shape. But the lab he set up—the Princeton Plasma Physics Laboratory (PPPL) in New Jersey—switched to a simpler method for later stellarators: winding more coils of wire around a conventional torus tube like stripes on a candy cane to create a twisting magnetic field inside.
In a tokamak, a design invented in the Soviet Union in the 1950s, the twist comes from within. Tokamaks use a setup like an electrical transformer to induce the electrons and ions to flow around the tube as an electric current. This current produces a vertical looping magnetic field that, when added to the field already running the length of the tube, creates the required spiraling field lines.
Both methods work, but the tokamak is better at holding on to a plasma. In part that’s because a tokamak’s symmetry gives particles smoother paths to follow. In stellarators, Anderson says, “particles see lots of ripples and wiggles” that cause many of them to be lost. As a result, most fusion research since the 1970s has focused on tokamaks—culminating in the huge ITER reactor project in France, a €16 billion international effort to build a tokamak that produces more energy than it consumes, paving the way for commercial power reactors.
But tokamaks have serious drawbacks. A transformer can drive a current in the plasma only in short pulses that would not suit a commercial fusion reactor. Current in the plasma can also falter unexpectedly, resulting in “disruptions”: sudden losses of plasma confinement that can unleash magnetic forces powerful enough to damage the reactor. Such problems plague even up-and-coming designs such as the spherical tokamak (Science, 22 May, p. 854).
Stellarators, however, are immune. Their fields come entirely from external coils, which don’t need to be pulsed, and there is no plasma current to suffer disruptions. Those two factors have kept some teams pursuing the concept.
The largest working stellarator is the Large Helical Device (LHD) in Toki, Japan, which began operating in 1998. Lyman Spitzer would recognize the design, a variation on the classic stellarator with two helical coils to twist the plasma and other coils to add further control. The LHD holds all major records for stellarator performance, shows good steady-state operation, and is approaching the performance of a similarly sized tokamak.
Two researchers—IPP’s Jürgen Nührenberg and Allen Boozer of PPPL (now at Columbia University)—calculated that they could do better with a different design that would confine plasma with a magnetic field of constant strength but changing direction. Such a “quasi-symmetric” field wouldn’t be a perfect particle trap, says IPP theorist Per Helander, “but you can get arbitrarily close and get losses to a satisfactory level.” In principle, it could make a stellarator perform as well as a tokamak.
The design strategy, known as optimization, involves defining the shape of magnetic field that best confines the plasma, then designing a set of magnets to produce the field. That takes considerable computing power, and supercomputers weren’t up to the job until the 1980s.
The first attempt at a partially optimized stellarator, dubbed Wendelstein 7-AS, was built at the IPP branch in Garching near Munich and operated between 1988 and 2002. It broke all stellarator records for machines of its size. Researchers at UW Madison set out to build the first fully optimized device in 1993. The result, a small machine called the Helically Symmetric Experiment (HSX), began operating in 1999. “W7-AS and HSX showed the idea works,” says David Gates, head of stellarator physics at PPPL.
That success gave U.S. researchers confidence to try something bigger. PPPL began building the National Compact Stellarator Experiment (NCSX) in 2004 using an optimization strategy different from IPP’s. But the difficulty of assembling the intricately shaped parts with millimeter accuracy led to cost hikes and schedule slips. In 2008, with 80% of the major components either built or purchased, the Department of Energy pulled the plug on the project (Science, 30 May 2008, p. 1142). “We flat out underestimated the cost and the schedule,” says PPPL’s George “Hutch” Neilson, manager of NCSX.
IPP/Wolfgang Filser
Wendelstein 7-X’s bizarrely shaped components must be put together with millimeter precision. All welding was computer controlled and monitored with laser scanners.
BACK IN GERMANY, the project to build W7-X was well underway. The government of the recently reunified country had given the green light in 1993 and 1994 and decided to establish a new branch institute at Greifswald, in former East Germany, to build the machine. Fifty staff members from IPP moved from Garching to Greifswald, 800 kilometers away, and others made frequent trips between the sites, says Klinger, director of the Greifswald branch. New hires brought staff numbers up to today’s 400. W7-X was scheduled to start up in 2006 at a cost of €550 million.
But just like the ill-fated American NCSX, W7-X soon ran into problems. The machine has 425 tonnes of superconducting magnets and support structure that must be chilled close to absolute zero. Cooling the magnets with liquid helium is “hell on Earth,” Klinger says. “All cold components must work, leaks are not possible, and access is poor” because of the twisted magnets. Among the weirdly shaped magnets, engineers must squeeze more than 250 ports to supply and remove fuel, heat the plasma, and give access for diagnostic instruments. Everything needs extremely complex 3D modeling. “It can only be done on computer,” Klinger says. “You can’t adapt anything on site.”
By 2003, W7-X was in trouble. About a third of the magnets produced by industry failed in tests and had to be sent back. The forces acting on the reactor structure turned out to be greater than the team had calculated. “It would have broken apart,” Klinger says. So construction of some major components had to be halted for redesigning. One magnet supplier went bankrupt. The years 2003 to 2007 were a “crisis time,” Klinger says, and the project was “close to cancellation.” But civil servants in the research ministry fought hard for the project; finally, the minister allowed it to go ahead with a cost ceiling of €1.06 billion and first plasma scheduled for 2015.
After 1.1 million construction hours, the Greifswald institute finished the machine in May 2014 and spent the past year carrying out commissioning checks, which W7-X passed without a hitch. Tests with electron beams show that the magnetic field in the still-empty reactor is the right shape. “Everything looks, to an extremely high accuracy, exactly as it should,” IPP’s Thomas Sunn Pedersen says.
Approval to go ahead is expected from Germany’s nuclear regulators by the end of this month. The real test will come once W7-X is full of plasma and researchers finally see how it holds on to heat. The key measure is energy confinement time, the rate at which the plasma loses energy to the environment. “The world’s waiting to see if we get the confinement time and then hold it for a long pulse,” PPPL’s Gates says.
Success could mean a course change for fusion. The next step after ITER is a yet-to-be-designed prototype power plant called DEMO. Most experts have assumed it would be some sort of tokamak, but now some are starting to speculate about a stellarator. “People are already talking about it,” Gates says. “It depends how good the results are. If the results are positive, there’ll be a lot of excitement.”

Posted in Physics



Research into fusion has gone down a blind alley, but a means of escape…
ECON.ST

2015年10月23日 星期五

幼稚的核能發電科學教育

10月24日周末的晨間新聞:苗栗政府的臨時雇員太多 (這種問題台北市也有,柯市長不敢碰)---辦公室擠滿人---必須裁撤,不過他們要求採用勞基法的解雇待遇,抗議、發傳單。現在的中央政府採用無政府管理方式,出錯了,無法負荷再自己"砍人"。

民視的"科學再發現"探討核能發電,完全淪為台電的代言:"核能最廉價"的說詞,完全不考慮風險與壽命周期總成本--污染處理成本等,所以是幼稚的宣傳品

2015年10月21日 星期三

Sorry, Einstein. ‘Spooky Action’ Looks Real.

The Economist

Einstein was troubled by how two particles can communicate with each other even if they are on opposite sides of the galaxy. Could it be true? Yes, scientists have now shown

The two final loopholes in how quantum entanglement works have just been closed
ECON.ST



Sorry, Einstein. ‘Spooky Action’ Looks Real.

A study in the Netherlands supports a long-held claim of quantum theory, one that Einstein refused to accept, that objects separated by great distance could affect each other’s behavior.

日本物理界的壯舉─從神岡微中子到ILC計劃 (陳健邦)


陳健邦觀點:日本物理界的壯舉─從神岡微中子到ILC計劃

 2015年10月21日 06:10

探測微中子的超級神岡探測器(Super-Kamiokande)
探測微中子的超級神岡探測器(Super-Kamiokande)
2015年10月6日、在日本東北的岩手縣立大學,聚集了近百位的大學員工和媒体工作者,等待收看網路傳來的諾貝爾物理獎消息。午後6時45分, 瑞典皇家科學院的祕書長揭曉說: 「今年獲獎的,是有關於某一宇宙中人數最眾多的族群,其身份特徵可能轉變的發現。」 "This year's prize is about changes of identity among some of the most abundant inhabitants of the universe." 此一敘述的精確物理含義,對大多數人而言,是難以掌握的。接著,人們清楚聽到了,物理獎授予加拿大的亞瑟·麥克唐納(Arthur Bruce McDonald)和日本東京大學的梶田隆章,表彰他們發現了微中子振盪(neutrino oscillation)現象,從而證實了微中子的質量不為零。岩手縣立大學現場的人群,在啊的一聲之後,是嘆息,是一片靜默。
梶田隆章的得獎,其他日本人普遍興奮。岩手大學的人群反應為何卻有失落之情?岩手大學2015年4月才上任的校長鈴木厚人,是梶田隆章的同門前輩,也是微中子實驗物理的專家。這嘆息,一是為鈴木厚人,另外則是為了一振興東北的雄圖,國際直線對撞機,ILC計劃之難產而嘆。
2015年諾貝爾物理學獎得主梶田隆章(美聯社)
2015年諾貝爾物理學獎得主梶田隆章(美聯社)
岐阜縣的飛驒高山一帶是富有舊日本風情的旅遊勝地,在往神岡的公路旁,建有一特殊造型的神岡星空小巨蛋(Skydom) 。此一星星和旅人的驛站,販賣土產和提供餐飲服務及旅游資訊。為什麼日本人會蓋了這樣一座外太空造型的公路休息站來迎接旅客?
這個「星星和旅人的驛站」,是在等待微中子,也等待諾貝爾物理獎的到來。終於在2002年10月,神岡町的緊急廣播響起,播放出:「我們大家長年的好鄰居,東京大學宇宙線研究所神岡實驗室的小柴昌俊教授,得到了諾貝爾物理獎。」這離上一次日本人的諾貝爾物理獎,1973年的江崎玲於奈,隔了29年,對日本的學術界而言,意義重大。
神岡星空小巨蛋圖示。(網頁截圖)
神岡星空小巨蛋圖示。(網頁截圖)
話說1950至1970年代,高能物理是物理學的研究主流。歐洲和美國紛紛投入經費建造大型的粒子加速器。由於所需的費用太高,又很難說會有什麼實用價值,不易得到足夠預算的支持。日本東京大學的小柴昌俊決定另闢途徑,利用來自外太空具有高能量的宇宙線,「靠天吃飯」來進行「窮人的高能物理」實驗。小柴昌俊提新計劃,將實驗設備埋設在深山中一個廢棄礦坑之中。1981年,小柴昌俊開始指揮弟子們在神岡礦坑地下的實驗進行建設工程。
最初,神岡實驗的設計是為了觀測質子的衰變,必須排除來自其他輻射雜訊的干擾,而深入地下一公里。小柴昌俊的團隊花了兩年,可是找不到質子衰變的跡象。於是轉移目標,又花了兩年改善提升儀器的靈敏度,準備觀測來自太陽內部核融合反應所產生的微中子。一九八七年二月,設備完成改善並運轉。就在此時,一位天文學家給在神岡做研究的朋友發來傳真信說:「大麥哲倫星雲內發生超新星爆炸,你們有看到嗎?」這次超新星爆炸,在十六萬光年之外,人生百年難得一見,根據理論會放出大量光子和大量高能量微中子。神岡的研究者取出實驗記錄磁帶送回到二百多公里之外的東京大學本部做分析,證實在十秒間共觀測到來自超新星的十一個微中子。當時,小柴再過一個月就要由東大退休了,這真是從天而降的禮物。神岡設施也意外地變身為「微中子天文觀測站」,吸引了國外的支持合作。
從前人們觀測星空,只能使用天文望遠鏡,利用可見光、無線電波來探索宇宙和天體之謎。小柴昌俊利用神岡町礦山地下的實驗設備,偵測到來自遙遠星空的微中子,得以藉之研究天體物理,開拓了「微中子天文學」的領域,他的學生戶塚洋二著書《從地下探索天上的奧秘》,回顧了他們從基本粒子研究轉向探索宇宙物理的歷程。小柴昌俊因此得到日本國民的最高榮譽「文化勳章」,也得到以色列的沃爾夫獎。
神岡實驗室的Logo,涵義:從地下探索星空的奧秘。
神岡實驗室的Logo,涵義:從地下探索星空的奧秘。
小柴常對學生提示兩件事:其一,「我們是用國民納稅的血汗錢來追求我們的夢想,買儀器時要努力省錢,不可依生意人所開的價格。」得獎後,他特別感謝濱松公司,當年為製造實驗所需的大型光電子倍增管,容忍了他的無理要求,賠了三億日圓,交出成品,成就了神岡實驗。其二,「想成為研究者,先要隨時抱著三、四個有希望的「研究鳥蛋」,機緣成熟時,該會有鳥破殼飛出吧。」好好把握,幸運會來拜訪有準備的人。
大學時代,小柴必須打工維持家中生計,很少去上課,他在2001年東大畢業典禮中應邀致詞時,特意展示他的「爛成績單」。他說:「成績單不是未來人生的保證。」
記者問他何以能得到諾貝爾獎,小柴回答:「白天專心做研究,回家後看水戶黃門(指為民除害的德川光國,可說是,日本的包青天)電視劇。」記者再問:「為什麼愛看水戶黃門?」小柴說:「看到壞傢伙被好人抓起來,就覺得很開心。」

神岡實驗的中挫與復原

自1930年,沃爾夫岡·包立(Pauli)為了解釋原子核的貝他衰變,而提出了微中子(neutrino) 存在的假說。直到1956年,物理學家才從核反應堆中的誘發反應,得在微中子存在的證據。
理論上,微中子彌漫在宇宙之中,無所不在。可是,微中子僅參與弱交互作用,與普通物質不產生反應,在宇宙中穿行無阻,難以被偵測,被視做基本粒子族群中的「隱身人」,長久以來,認為微中子的質量為零。自大爆炸宇宙創生後,微中子即佈滿於太空中,微中子的質量雖然微乎其微,但只要不是零,其質量的大小對宇宙演化和物理學的大統一理論有重大意義。
在小柴昌俊的突破之後,微中子實驗成為宇宙論和基本粒子物理交會的最前線。神岡實驗室原本只有數十人的研究小組,在觀測到來自超新星的微中子之後,得到日本政府的經費支持,建造功能更好的超級神岡探測器,聚集了數百名的國際團隊。戶塚洋二接棒主持研究。於1996年啟用新的超級神岡探測器。
2002諾貝爾物理獎得主小柴昌俊。
2002諾貝爾物理獎得主小柴昌俊。
1998年,在高山市「微中子物理學・宇宙物理學國際會議」,梶田隆章代表美日的研究團隊宣讀論文,宣佈發現「微中子具有質量」,全場人員起立,不停的掌聲響起,有如在一場音樂盛會後,向演出者致敬。
擔任宇宙線研究所所長的戶塚洋二,人稱「鬼軍曹」(魔鬼教練), 2000年,戶塚洋二動了大腸癌手術。2001年11月,因為意外事故,超級神岡探測器的數千隻光電倍增管突然爆裂,實驗陷入困境之中。戶塚洋二忍病,領導重建再開啟實驗。    
梶田隆章分析觀測來自太陽的微中子時,發現數據有異樣,即太陽微中子在抵達地球之前的數目會變化,即有些會離奇消失,依此推測有中微子振盪現象的存在,即三種不同的微中子,在行進中會互相轉變類型,而未能被特定的探測器所檢出。
亞瑟·麥克唐納在加拿大安大略省所領導的SNO實驗室,也在長期的國際合作下,得到和超級神岡實驗互為佐證的結果。

物理巨匠的師生情

小柴昌俊何以能克服萬難完成了戰後日本物理學界最重要的實驗?為何神岡實驗室在微中子物理實驗能領先?日本的物理學家,為何能走出自己獨特的道路?
小柴昌俊的大學時代是日本戰後的艱困期,小柴必須打工維持家中生計,很少去上課,他在2001年東大畢業典禮中應邀致詞時,特意展示他的“爛成績單”。他說:「成績單不是未來人生的保證。」
2006年在京都的「湯川、朝永生誕一百年紀念研討會」上,小柴昌俊用以下故事做開場白,追思朝永振一郎(1965年諾貝爾獎得主)對他的影響:「有一次在同學的婚宴上,朝永先生做為證婚人,指著新郎說,這是跟我學物理的學生。在座的小柴君,是向我學喝酒的學生。那一瞬間,我感動的落淚。」小柴昌俊沒跟朝永振一郎學過物理,但因長輩的介紹,得到朝永振一郎的關照,時相過從一起喝酒暢談。東大畢業後,因朝永振一郎的推薦信,小柴昌俊得到獎學金去美國的羅徹斯特大學留學。
從左到右:1965年諾貝爾獎得主朝永振一郎及共同獲獎的理察·費曼及朱利安·施溫格。(維基百科)
從左到右:1965年諾貝爾獎得主朝永振一郎及共同獲獎的理察·費曼及朱利安·施溫格。(維基百科)
小柴昌俊拿到美國的博士之後,回到東京大學任副教授,但不吃香。當時,日本沒有高能量的加速器,小柴昌俊的幾位學生:須田英博、戶塚洋二、折戶周治、鈴木厚人都被派去德國、義大利合作,從中學習累積了儀器設計和實驗數據分析的技術。這四位是小柴昌俊的第一代骨幹學生,成為日本高能物理學界獨領風騷的學派。可惜其中三位都壯年早逝,可說是物理學界中的過勞死族群。梶田隆章受業於小柴昌俊、戶塚洋二,算是第二代學生了。
小柴曾經說「在我的弟子當中,有二人夠格得諾貝爾獎」。2007年,亞瑟·麥克唐納和戸塚洋二共同獲得富蘭克林獎章,被認為離諾貝爾獎只差一步了。不幸,2008年7月,戶塚洋二因大腸癌去世。小柴在《文藝春秋》撰文追悼說,「戶塚只要再多活十八個月,必能獲得諾貝爾獎」。2014年,美國《今日物理》(Physics Today)預測,因戶塚洋二已故,梶田隆章可望與亞瑟·麥克唐納共享諾貝爾物理獎。這一預言終於實現。
鈴木厚人也是超級神岡探測器的主要研究人員,做出許多提升超級神岡探測器性能的貢獻。其實這些大團隊的合作實驗,追求靈敏度的一再提高,許多成果,往往是建立在別人的心血之上。
梶田隆章在得獎後,回到東京大學的安田講堂說:「在實驗現場日夜不休進行研究工作的是研究生和技術人員,這是結集了非常優秀的年輕力量才得到的成果,才有諾貝爾獎的成就。」對東京大學深表謝意。

振興東北的雄圖:ILC計劃

在歐洲CERN的大強子對撞機(LHC)實驗發現希格斯粒子之前,國際高能物理學界就寄望能早日建造下一世代大型實驗設施「國際直線對撞機」(ILC),扮演「希格斯粒子工廠」的角色。此國際合作計劃,經專家小組研究八年之後,完成初步設計,提出計劃書,打算建設全長31公里(可再延長至50公里)的直線隧道型超高能量的正負電子對撞機,並在世界各地進行研究基地的選址。日本的選址評估小組建議以日本東北岩手縣的北上山地為基地。
在311東日本大震災之後,東北人士不只是期望「復原」,而是有所突破振興。在許多學術會議、電視宣傳、說明會之後,岩手縣人士大力推動,將這項建設視為311東日本大震災災後重建事業的一環。又說,ILC計劃若能在日本成功進行,日本會成為一受人尊敬的國家。物理學界則希望,能在CERN之後,在日本打造出另一高能物理研究的聖地。
此計劃預估耗資50億至100億美金,環境整理和儀器設備的建設需費時十年,研究工作再進行十年。估計可吸引一萬名國際專家移居日本,研究園區可形成一國際化的新市鎮,對日本社會改造發揮影響,並提供25萬人的工作機會。因建設經費的約半數費用由興建地國家負擔,因此歐美國家對於爭取建設顯得消極。啟動之後,又有預算增加的疑慮,日後的營運也要巨大的支出。雖然高能物理學界極力遊說,日本政府在徵詢「日本學術會議」的意見之後,決定暫不向國際提出申請。
日本物理學界推動ILC計劃是以「高能加速器研究機構」為主力。之前,鈴木厚人從2006年4月開始擔任高能加速器研究機構長,至2015年才卸任。鈴木厚人,也一直被認為是有望得諾貝爾物理獎。地方人士認為,鈴木厚人如果得諾貝爾物理獎,對岩手縣爭取ILC會有大助益。因期望落空,才有失落之情。
鈴木厚人。(泉萩會官網)
與諾獎失之交臂的鈴木厚人。(泉萩會官網)
當年被問到:「捕捉到微中子,有什麼用?」小柴昌俊說:「沒有用。沒用的研究也是重要的。只要能增加人類的共通知識和智慧財產,我想也是好的。」今年,得知梶田隆章獲獎之後,鈴木厚人說:「就首先發現微中子的質量此一偉業而言,超級神岡團體成員的得獎是妥當的。微中子不再是『幽靈粒子』了、終於被證實和其他的基本粒子具有同様的性質。」
當年小柴昌俊找上他的高中同學,當時日本的大藏大臣宮澤喜一,請求支持神岡實驗預算,只要求四億日圓。如今ILC計劃已不是「窮人的高能物理」實驗,其預算上看一百億美金,預算相差在千倍以上,即使富人也玩不起,是其啟動的最大難題。ILC計劃的宣傳,以「逼近宇宙創生之謎」為口號。高能物理的尖端研究,畢竟離一般人太遠。希格斯粒子、微中子振盪,這些名詞意義的了解,要對量子力學理論有深度理解,非常人所能領悟。ILC計劃的推動,可能會再停擺一陣子。
微中子,中國大陸物理界譯為中微子。受到神岡實驗的刺激,中國也選擇在既有的核能發電廠附近,通過國際合作,先後建立了大亞灣、江門兩個中微子實驗站,希望不在高能物理的尖端研究中缺席。江門中微子實驗站設定的主題,更直指「測量中微子質量順序」,試圖領先其他團隊突破中微子質量之謎。當年方勵之在研究宇宙論時,想到中微子在宇宙中所扮演的角色和自己的命運,這麼說過:「常會覺得自己只不過是一個中微子,知識份子就像宇宙中的中微子,是微不足道的,但只要有很小的質量,宇宙的命運也就決定於這些不足道者。」或許,新一代中國的物理學家在探索中微子質量之謎時,會有人再思索方勵之的這一段話。
*作者為上市公司獨立董事,專欄作家