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已有 5147 次阅读 2011-10-5 01:10 |系统分类:海外观察|关键词:2011,诺贝尔奖,物理学,伯克利,宇宙学,创新,可持续发展,战略,大爆炸,导师,真理,科学,起源,归宿,冰川,美国,宇航,天文学,宇宙学,,星系,暗物质,暗能量,宇宙猜想,相对论,劳伦斯伯克利国家实验室,LBNL| 物理学, 诺贝尔奖, 宇宙学, 2011, 伯克利


大家可能还对2006年获得诺贝尔奖的伯克利劳伦斯伯克利国家实验室(LBNLGeorge Fitzgerald Smoot III记忆犹新,现在又有一位劳伦斯伯克利国家实验室(LBNL)的诺奖获得者产生,他就是Saul Perlmutter教授Saul Perlmutter教授现在成为伯克利近11年的第15位诺奖获得者、第9位物理奖获得者!牛!


Saul Perlmutter教授将在伯克利拥有专属的、永久的、蓝色的、只有诺贝尔奖获得者才有资格停车的停车位!




Saul Perlmutter awarded 2011 Nobel Prize in Physics

By Robert Sanders, Media Relations | October 4, 2011


Saul Perlmutter, who led one of two teams that simultaneously discovered the accelerating expansion of the universe, has been awarded the 2011 Nobel Prize in Physics, to be shared with two members of the rival team.

UC Berkeley and LBNL physicist Saul Perlmutter (Roy Kaltschmidt, LBNL)

Perlmutter, 52, a professor of physics at the University of California, Berkeley, and a faculty senior scientist at Lawrence Berkeley National Laboratory (LBNL), led the Supernova Cosmology Project that, in 1998, discovered that galaxies are receding from one another faster now than they were billions of years ago.

He will share the prize with Adam G. Riess, 41, of The Johns Hopkins University and Brian Schmidt, 44, of Australian National University’s Mount Stromlo and Siding Spring Observatories, two members of the competing High-Z Supernova Search team. When the discovery was made, Riess was a postdoctoral fellow at UC Berkeley working with astronomer Alex Filippenko, who at different times was a member of both teams.

Perlmutter is the fifth Nobel winner for UC Berkeley in the past 11 years, and the 22nd Nobelist overall. This is the ninth Nobel in Physics awarded to a UC Berkeley faculty member, the most recent winner being George Smoot in 2006.

The most recent National Research Council nationwide rankings identify theDepartment of Physics as among the best in the nation.

The accelerating expansion means that the universe could expand forever until, in the distant future, it is cold and dark. The teams’ discovery led to speculation that there is a “dark energy” that is pushing the universe apart. Though dark energy theoretically makes up 73 percent of the matter and energy of the universe, astronomers and physicists have so far failed to discover the nature of this strange, repulsive force.

In recent years, Perlmutter has been working with NASA and the U.S. Department of Energy (DOE) to build and launch the first space-based observatory designed specifically to understand the nature of dark energy. A dark-energy mission was named the top telescope-building priority in an August 2010 report from a blue-ribbon committee of the National Academy of Sciences.

Using supernovae as cosmic yardsticks

Perlmutter was a postdoctoral fellow at LBNL when he decided to focus on Type Ia supernovae as yardsticks to measure the geometry of the universe. Astronomers knew that the universe was expanding, but the main question at the time was whether the universe was open, and thus destined to expand forever, or closed, meaning that the expansion would eventually stop and the universe would collapse back on itself.

He and his LBNL team were puzzled by initial results in 1997 indicating that, not only was the universe’s expansion not slowing down, it was speeding up, contrary to all cosmological theories.

“The chain of analysis was so long that at first we were reluctant to believe our result,” Perlmutter said. “But the more we analyzed it, the more it wouldn’t go away.”

The High-Z team came to the same conclusion at the same time, based on an independent set of Type Ia supernovae.

“There was no hint of this when we started the project,” Riess said in 1998 while still a Miller Postdoctoral Research Fellow at UC Berkeley. “We expected to see the universe slowing down, but instead, all the data fit a universe that is speeding up.”

The discovery, reported by both teams in 1998, has since been bolstered by independent measurements. The earliest and most important of these confirmations were by the Millimeter Anisotropy eXperiment IMaging Array (MAXIMA), a balloon-borne experiment led by UC Berkeley physicist Paul Richards, and the Balloon Observations Of Millimetric Extragalactic Radiation and Geophysics (BOOMERanG) experiment, led by the late Andrew Lange, a former UC Berkeley post-doctoral fellow, and Paolo De Bernardis.

Team effort

“This discovery was very much a team effort,” Perlmutter stressed, citing the efforts of the Supernova Cosmology Project’s individual members in theoretical studies of supernova dynamics, the detection of supernovae near and far, data analysis and interpretation, and other research components.

Perlmutter graduated magna cum laude in physics from Harvard University in 1981 and began graduate work at the UC Berkeley, where he gravitated toward the study of astrophysics. He completed his Ph.D. with Richard Muller, UC Berkeley professor of physics, in 1986.

While still a postdoctoral fellow, Perlmutter teamed up with fellow post-doc Carl Pennypacker to develop the technology to use Type Ia supernovae –which are bright enough to be seen across the universe – to measure cosmological distances. Other astronomers had observational data suggesting that Type Ias were all about the same intrinsic brightness, so that their apparent brightness from Earth could be used to calculate their distance.

With observing time on several telescopes around the world, the Supernova Cosmology Project was able to test and improve its techniques. When the team eventually sat down with new data on Type Ia supernovae to calculate the basic parameters of the universe, however, the results were too bizarre to be believed.

“The most striking part of the project was the huge skepticism,” recalled Pennypacker, now with UC Berkeley’s Space Sciences Laboratory and a guest in LBNL’s Physics Division. The skepticism was not only about proposed techniques, but about the underlying science. “Nobody believed we could do it,” he said,“and it was an enormous challenge to get things done.”

Perlmutter, a member of the National Academy of Sciences and a fellow of the American Academy of Arts and Sciences, has received numerous honors, including the 2006 Shaw Prize, shared with Schmidt and Riess; the 2007 Gruber Cosmology Prize, which he shared with his entire Supernova Cosmology Project team and the High-Z Supernova Search team; the 2003 California Scientist of the Year award; and the 2002 E. O. Lawrence Award in physics from the Department of Energy.

He lives in Berkeley with his wife and daughter.

Further information:



所属:沪江英语 来源:nobelprize.org

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2011 with one half to Saul Perlmutter, and the other half jointly to Brian P. Schmidt and Adam G. Riess, for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.


"Some say the world will end in fire, some say in ice..."


What will be the final destiny of the Universe? Probably it will end in ice, if we are to believe this year's Nobel Laureates in Physics. They have studied several dozen exploding stars, called supernovae, and discovered that the Universe is expanding at an ever-accelerating rate. The discovery came as a complete surprise even to the Laureates themselves.


In 1998, cosmology was shaken at its foundations as two research teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.


The research teams raced to map the Universe by locating the most distant supernovae. More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors (CCD, Nobel Prize in Physics in 2009), opened the possibility in the 1990s to add more pieces to the cosmological puzzle.

研究队伍用定位距离地球最远的超新星的办法来绘制宇宙地图。到了20世纪90年代,更精密的陆地和太空望眼镜装置、更强大的计算机系统以及全新的数字成像传感器(CCD, 2009年获得了诺贝尔物理学奖),为人类拼制宇宙这副拼图提供了可能性。

The teams used a particular kind of supernova, called type Ia supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected - this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.


For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.


The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma - perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.





  首次发现宇宙微波背景辐射是在1964年。美国贝尔电话实验室的两位科学家阿罗·彭齐亚斯和罗伯特·威尔逊为此获得1978年诺贝尔物理学奖。他们起初曾将这种辐射误为是自己的接收机上不相关的噪声(实际上, 宇宙微波背景是每当我们的电视机正常传输中断时接受到的那种“雪花”噪声的一部分)。但是, 早在1940年代,伽莫夫、阿尔弗和赫尔曼就做出了微波背景的理论预言,对后来关于宇宙起源的持续讨论作出了重要贡献。

  当时主要有两种宇宙学理论在互相竞争: 或者宇宙在最初的大爆炸中诞生然后继续膨胀, 或者它总是处于在一种稳恒状态。大爆炸图景实际上预言了微波背景辐射的存在, 因此,彭齐亚斯和威尔逊的发现自然让那种理论格外令人可信。


  根据大爆炸图景, 我们的宇宙是从一种极热的状态发展而来。关于宇宙的这种原初条件迄今尚无完善的理论, 但看起来不久之后它就被密集得难以置信的辐射所充满。由这样一种发光“体”发出的辐射以特定方式分布于不同的波长,就像恒星一样,其发光的颜色(能谱)只取决于温度:温度低时,颜色发红;温度高时,颜色发蓝。除温度之外,我们对这种辐射一无所知,但是可以确切地预言它的能谱看起来像什么样子。这种被称为黑体辐射的能谱也可以在实验室产生, 德国科学家普朗克第一个描述了它们的特殊形状。我们自己的太阳实际上是“黑体”, 尽管它的光谱没有宇宙微波背景辐射那么完美。

  根据大爆炸图景, 背景辐射随宇宙膨胀逐渐变冷。然而能谱的原初黑体形状被保存下来。当辐射发出的时候, 后来形成我们宇宙的混沌物质仍然是非常热的,温度大约在3000℃左右。然而我们今天测量到的背景辐射已显著变冷, 现在对应于一个温度仅为绝对零度之上2.7度的物体散发的辐射。这意味着辐射的峰值波长增加了(黑体辐射的规律是温度越低, 峰值波长越长)。所以现在发现的背景辐射波长落到了毫米至厘米之间的微波区域。



宇宙微波背景的第一批测量是在高山、火箭和气球上做的。地球大气吸收了许多辐射, 因此测量需要在非常高的地方进行。但即使在这样的高处,可能实际上被测量的也只有属于背景辐射能谱的一小部分。能谱内一大部分波长的辐射被大气如此高效地吸收, 以至测量必须在地球大气之外进行。因为首先,地面测量(包括由彭齐亚斯和威尔逊所做的测量) 不能充分显示出辐射的黑体性质。这就使人们难于知道背景辐射是否真正是大爆炸图景预言的那种类型。此外, 局限于地面的仪器不容易探查宇宙的所有方向,使它难以证明这种辐射的确是各向同性的真实背景。从卫星上进行测量能同时解决这两个问题——仪器可能置于大气之上,并且测量可容易地及于四面八方。

1974年,美国宇航局邀请天文学家和宇宙学家为新的空基实验递交提案。这导致了COBE项目的启动。马瑟是这个庞大合作体(包含1000名科学家、工程师和其他人士)的真正动力。他也负责一台星载仪器(远红外绝对分光光度计), 用于探查背景辐射的黑体谱。斯穆特则负责另一台重要的仪器(较差微波辐射计), 用以寻找不同方向背景辐射温度的微小变化。

美国宇航局原来打算由一架航天飞机发射COBE 。但是,1986年挑战者号爆炸的悲剧事故以后, 航天飞机的运作被中断了几年。这意味着COBE的未来处于危险之中。圆熟的交涉最后使马瑟及其合作者为COBE获得了专用的火箭, 卫星最后在19891118日发射。 9分钟观察以后就得到第一批结果: COBE 记录了一条完美的黑体谱! 当这条曲线后来在19901月举行的一次会议上展示时引起了全场起立欢呼。COBE 曲线是曾经测量过的最完美的黑体谱之一。


但这只是COBE 的部分结果。斯穆特负责的实验,其设计目标是寻找微波背景不同方向的微小变化。宇宙不同部分微波背景温度的微小变化,可以提供关于星系和恒星如何形成的新线索,说明物质为什么不是像均匀的泥浆那样散开,而是这样集中于宇宙中特定的位置。微小的温度变化能显示物质在何处开始聚集。这个过程一旦开始, 剩下的事就由万有引力主导: 物质吸引物质, 导致恒星和星系形成。然而若没有一个开始的机制, 不论银河系,太阳,或是地球都不会存在。

试图解释物质的聚集如何开始的理论,与原初宇宙中的量子涨落有关。同样类型的量子涨落产生于物质和反物质粒子不断的产生和湮灭。今天宇宙中测量到的温度变化,可以认为是这些量子涨落的结果,而且根据大爆炸理论,恒星、行星、最后生命能够演化出来也要归因于此。没有这些量子涨落, 构成我们的物质会以完全另外的形式均匀散布于宇宙之中。


当科学家们计划COBE 实验时最初的想法是:为解释星系形成需要的微波背景温度变化,大约会是千分之一摄氏度。这已经很小了, 但后来发现情况更糟: COBE 还在建造时, 有研究者报告说,暗物质(我们不能看见的宇宙中的大部分物质) 的影响意味着,要寻找的温度变化可能是在十万分之一度的范围。暗物质本身实际上是物质凝聚的一个重要动因, 这意味着为解释这个过程的启动所需要的温度变化比早先设想的更小。

发现这样极小的温度变化是一个巨大挑战。即使重新设计仪器,COBE 得到的结果仍然变得比期望更加不确定和难于解释。这种变化是如此之小, 以致它们很难与不相关的噪声区别开——那怎么能知道它们的确是真实的呢? 当结果最终在1992年发表时,发现它们能与地面测量关联起来:尽管地面测量比COBE的测量更加不确定,但两者记录到温度变化的空间方向却是完全一致的。



COBE的成功的鼓舞下,第二代宇宙背景各向异性探测卫星(WMAP)于2001年升空。由于WMAP的空间分辨率从其前辈COBE7°提高到了0.2°,使得人们可以通过比较不同角度内测量到的温度变化,以前所未有(约1%)的精度测定宇宙中可见物质、暗物质以及暗能量的比例(分别约为4%,23%和73%)。因此, COBE项目可以并且已被看作为宇宙论成为精确科学的起点:宇宙学的计算第一次能与真实测量数据进行比较,这使得现代宇宙论成为一门真正的科学。

COBEWMAP的测量为评估宇宙的基本形状提供了依据。COBE实验也开创了几个宇宙论和微粒物理学的新领域。新宇宙学测量目的在于更好的理解在背景辐射发出之前时刻发生的过程。在粒子物理学方面,目标是了解暗物质由什么构成。这是很快将在欧洲核研究中心使用的新LHC 加速器(大型强子对撞机) 的任务之一。




大约14年前,人们一度以为有了完美的答案:通过对于宇宙背景微波辐射的观测,天文学家最终验证了1929年爱德文哈勃(Edwin Hubble)的猜想,即宇宙诞生于大约137亿年前的大爆炸(Big Bang)。之后,随着宇宙的演化,银河系、太阳系、地球,乃至我们人类自身,都陆续登场。

200610月,正是凭借这一重要成就,美国科学家乔治斯穆特(George F Smoot)、约翰马瑟(John C Mather)分享了该年度的诺贝尔物理学奖。

但我们对宇宙的了解,显然也还刚刚开始。就在此一个月后,美国航空航天局(NASA)公布的最新研究结果表明:至少在90亿年前,一种被称为暗能量”(dark energy)的神秘力量已经存在。


尽管这一结果仍不能确定地告诉我们宇宙的未来是怎样的,但显然,它为我们彻底理解宇宙的运行规律带来了新的曙光。相关的论文也将发表在20072月美国《天体物理学报》(The Astrophysical Journal)上。

这一研究小组的负责人、美国约翰霍普金斯大学(John Hopkins)教授阿德姆瑞斯(Adam Riess)在接受《财经》记者采访时表示:我们距离真正了解暗能量仍然很远。但很显然,这是非常重要的一步,因为它给出了更多的线索’(clue)



1998年,美国加州大学伯克利分校(UC Berkeley)物理学教授、劳伦斯伯克利国家实验室(LBNL)高级科学家索尔皮尔姆特(Saul Perlmutter),以及澳大利亚国立大学布赖恩施密特(Brian Schmidt)分别领导的两个小组,通过观测发现,那些遥远的星系正在以越来越快的速度远离我们。




我们所熟悉的世界,即由普通的原子构成的一草一木、山河星月,仅占整个宇宙的4%,相当于金字塔顶的那一块。 下面的22%,则为暗物质。这种物质由仍然未知的粒子构成,它们不参与电磁作用,无法用肉眼看到。但其和普通物质一样,参与引力作用,因此仍可能探测到。作为塔基的74%,则由最为神秘的暗能量构成。它无处不在,无时不在,由于我们对其性质知之甚少,所以科学家还不清楚如何在实验室中验证其存在。惟一的手段,仍然是通过天文观测这种间接手段来了解其奥秘。对Ia类型超新星(supernova)的爆发进行观测,则是目前最主要观测手段。这种超新星是由双星系统中的白矮星(white dwarf)爆炸形成的,亮度几乎恒定。这样,通过测量其亮度,就可以知道其和地球之间的距离,进而了解其速度。 借助哈勃这样灵敏的天文仪器的帮助,我们至少可以观测到90亿光年之外,即了解宇宙在90亿年前的信息。






中国科学技术大学物理学教授李淼曾经半开玩笑地表示:有多少暗能量专家,就有多少暗能量模型。也许这种说法不无夸张之处,但暗能量在理论方面的混沌状况,从中也可见一斑。 其中,最具戏剧性的理论,则是复活爱因斯坦当年提出的宇宙常数”(cosmological constant)1917年,被认为是整个20世纪最伟大的科学家阿尔伯特爱因斯坦(Albert Einstein),为了建立一个稳态宇宙模型,最早提出了这个概念。不过,后来就连他本人也承认,宇宙常数只是一个错误的概念。

但暗能量的存在,则为宇宙常数提供了新的可能性。如果暗能量就是这个宇宙常数的话,那么它的力量强弱将只和宇宙的大小有关。随着宇宙的膨胀,其体积逐渐增大,因而暗能量也将逐渐增大。最终,它会达到一个临界点,使得宇宙从减速状态变成加速状态,并且一直加速下去。上海市第54中学 预一(1)叶梓

暗能量(Dark energy



根據愛因斯坦廣義相對論(general relativity),宇宙的膨脹速度與宇宙的能量密度及壓力有關,因此為了能夠解釋目前所觀測到的宇宙加速膨脹的暴漲理論(inflationary theory),我們需要引入暗能量,方能提供足夠的負壓力。

所謂暴漲理論是說:在宇宙尺度中,四大基本力:重力、電磁力、強作用力與弱作用力,我們只需考慮重力,因此根據重力相吸的特性,使宇宙在發生大霹靂爆炸後,一方面因為爆炸而膨脹,但另一方面,則受到重力吸引,因此目前宇宙膨脹,應是減速膨脹,即未來的膨脹速度應小於過去的膨脹速度,甚至將來有一天膨脹會停止而開始收縮,就好像簡諧振盪(simple harmonic oscillation,簡稱為SHO)一樣。然而目前種種觀測都不利於這種減速膨脹的模形,從1998年美國勞倫茲伯克萊國家實驗室(Lawrence Berkeley National Laboratory)的超新星(supernova)爆炸,到宇宙微波背景輻射(cosmic microwave background radiation,簡稱為CMBCMBRCBRMBR),種種證據都顯示宇宙正在作加速膨脹,因此暗物質的模型正式被提出。

除了上述的暴脹理論的宇宙能量密度,暗能量另一項有利的模型就是宇宙常數。所謂宇宙常數(cosmological constant)是愛因斯坦在1917年推導重力場的膨脹與收縮解時,為了維持靜態宇宙觀所引入的一個常數,然而在1929年哈伯提出宇宙膨脹理論以後,愛因斯坦非常懊惱提出宇宙常數這個概念,並宣稱這是他一輩子所犯下最大的錯誤。所謂宇宙常數是指如果宇宙中只存在一般物質,則宇宙膨脹加速度小於零,亦即宇宙應作減速膨脹,此時宇宙常數等於零,顯示宇宙因為重力吸引影響最大。反之,如果宇宙膨脹加速度大於零,意即宇宙作加速膨脹,此時宇宙常數大於零,顯示另外看不見的因子大於重力吸引的影響,因為這種能量與物質目前無法偵測,因此命名為暗能量與暗物質(dark matter)



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