哈勃拍到1006年超新星爆炸残余的特写镜头
据英国《新科学家》杂志报道，尽管中世纪的观天人在1000多年前看到了一颗恒星爆炸的景
象，但直到现代天文学爱好者才全面获得了其爆炸残余的惊人画面。因为哈勃望远镜最近已经拍到了银河系中一颗已经在1006年5月1日爆炸了的超新星残余的特写镜头――是一条非常壮观的光带。此爆炸是历史记载中最明亮的爆炸之一，肉眼就能看见。
科学家表示，此精巧模样的残余其实是来自此恒星爆炸的部分冲击波。而且，此暴动的残余还在爆炸之中，每小时大约移动1千万公里。此哈勃图像主要是由此残余的氢原子发射出的可见光、蓝光、黄绿光和近红外线光共同生成的合成图像。此扭曲光带的明亮部分是来自此爆炸的冲击波位于我们视线的边缘。
此超新星爆炸的残余在可见光下较昏暗，但天文学家用X射线光谱制成了极好的图像。（尼特）
1006年的超新星爆炸残余
据科学连线网报道，近日美国科学家进行了首次模拟电脑黑客攻击人类大脑的实验。实验不仅引起了FBI的注意，并且一些特殊的电脑网络案件也使网络安全专家担心万分。
据报道，在过去的一个月里，多位患有癫痫病的网友向警方报案称，他们在浏览一些网站的时候，发觉出现意识不清的现象，甚至有被人控制的感觉。FBI在经过调查后发现，一些电脑黑客在使用特殊的方法“攻击”使用电脑的癫痫病患者，故意使他们发病。
据报道，虽然在实验中，科学家没有发现模拟攻击可以控制人大脑的确切证据，但是发现了一些攻击在人脑功能上具有异常的反应。专家因此表示现在的科技能力还未能达到直接攻击人类大脑并控制那样的情况。
但目前电脑黑客的技术，有可能使电脑病毒攻击人类大脑功能成为现实。FBI在一个月前就发现有一个秘密的黑客组织利用技术，使网页出现大量不断闪烁的图像，意图很明显是为了引发癫痫患者发作。癫痫病患者浏览这些伪装成可以治疗他们疾病的网站时，这些闪烁的图片会诱使他们癫痫病发作，目前还不能肯定有多少人受到影响。
据美联社报道：这些黑客进入癫痫病联盟网站，意图似乎不在利益，黑客也并没有通过这些有害的网页以控制受害人的电脑。但反病毒软件安全研究员保罗-弗格森说：“我猜想这可能和青少年犯罪有同一性质，他们并没有意识到这件事造成了多大的危害。”
但是参与实验的专家担心，如果黑客使用其他方式攻击人类也不是没有可能，而且目前一些生物仿生技术的使用，使得黑客完全有机会利用网络来攻击人类大脑。
天文学家首次找到部分失踪物质
作者：刘妍 来源：新浪科技 发布时间：2008-5-9 10:5:46
宇宙气体网研究重大突破：天文学家首次找到部分失踪物质
这对于人类最终破解宇宙的奥秘具有重要意义
北京时间5月8日消息，据国外媒体报道，一个由多国天文学家组成的研究小组日前称，他们最近利用欧洲航天局发射的XMM—牛顿X射线卫星在宇宙中寻找到了部分失踪物质。这对于人类最终破解宇宙的奥秘具有重要意义。
寻找神秘的失踪物质
十年前，科学家们预言，大约一半的由失踪物质组成的原子是以低密度气体形式存在于宇宙间，它们填充在星系间广袤的空间中。宇宙中的所有物质都是以网状结构散布着，一团团星系便位于宇宙网中密集的节点上，它们是宇宙中最大的物体。天文学家们怀疑，低密度气体充斥着整个宇宙网的细丝。过去，由于气体的密度非常低，因此许多探测尝试都不得不受阻。如今，借助XMM—牛顿X射线卫星的高灵敏度，天文学家们发现了这些气体的最热部分，它浓缩了宇宙小区域中整个网丝的X射线放射，这有助于科学家们进一步了解宇宙网的进化过程。
科学家们预测，这些气体可能温度很高，因此会放射出低能量的X射线。然而，气体过低的密度使得观测极为艰难。天文学家们使用XMM—牛顿天文台对一对星系团Abell 222和Abell 223进行了观测，这对星系团距离地球23亿光年远，星系团系统的图像和光谱显示有一道热气体桥将两个星系团联结起来。研究小组的负责人、荷兰太空研究所的诺伯特•沃纳说：“我们在桥或网丝中观测到的这个热气体，可能是宇宙网中散漫气体温度和密度最高的一部分，这部分被认为是宇宙中约半数重子物质的组成物。”研究小组的另一成员亚历克西斯•费诺吉诺夫补充说：“此次有关失踪重子的最热部分的发现意义非常重大，因为目前我们有许多模型，且所有模型都预言失踪的重子是某种热气体的形式，不过在解释极端时却不一致。”
诺伯特•沃纳由此得出结论说：“这只是个开始。要搞清楚宇宙网中的物质分布，我们必须观测更多的星系团系统，并通过发射一个专门的空间望远镜来观测宇宙网，并且其灵敏度要比目前任何探测器都要高。我们的研究结果将对新探测器的研发提供可靠的必要条件。”欧洲航天局XMM—牛顿项目科学家诺伯特•查特尔评论此次发现说：“这次重大的突破对探测器研发而言是个好消息。经过艰辛的观测工作后，我们发现了这些气体，更重要的是我们目前已经知道从哪去寻找它。我希望未来能运用XMM—牛顿天文台，以宇宙中这种区域为目标，来进行后续研究。”
有助于揭开宇宙的奥秘
一直密切追踪失踪物质的天文学家找到了它们的部分隐藏位置：X射线卫星发现星系之间的空间存在着一片网状炽热气体，它们构成的质量远远超过我们的眼睛能看到的物质的质量。科学家以前已经预言了这些稀薄的云的存在，但是直到现在才被确证。它们让天文学家离找到所有的正物质和揭开宇宙奥秘更近了一步。
天文学家们相信，宇宙主要被两种未知的事物所支配：暗能量和暗物质。根据对大爆炸元素形成的研究，以及大爆炸辐射的微弱起伏，普通物质只占宇宙总组成的不到5%。在这不到5%中，只有一小部分以恒星和星系的形式存在，而较冷的气体云所占的比例更多。然而，望远镜所发现的普通物质还不足其总量的一半。理论家疑心，有一片由普通物质构成的稀薄气体分布在空间中，温度在100万度左右。这种炽热气体的迹象已经在附近的星系团中发现了，但是天文学家需要更多的细节才能看到其余的弥漫状气体网。
这个研究组通过观测另外两个明亮的闪光，发现了类似的细丝状气体。诺伯特•沃纳说，这些观测结果共同组成的结论指出，存在广泛分布的炽热气体网，而星系的引力还没有把它们拉进星系里。他谈到，XMM—牛顿X射线卫星发现的气体总量与“失踪的”普通物质的质量相一致。美国科罗拉多大学的天文学家米歇尔•舒尔说，这个研究表明X射线卫星可以发现一些以其他方式不可见的气体。“这个观测结果看上去是真实的，这是第一次，”舒尔说。“但是这只是冰山一角。”他预言，未来的X射线和紫外线望远镜将更加彻底的绘制出这个宇宙气体网的地图，并发现引力是如何让星系和恒星穿上了今天这样的炽热网状外衣的。
该文论证，也许子加速器是做SETI最好的工具，因为这种加速器可以产生大量的高能中微子，地外文明很有可能用中微子来和我们联系。就像一般加速器一样，缪子碰撞产生出来的中微子可以形成一个窄的有一定长度像铅笔一样的中微子束。缪子能量越高，中微子束的张角越小。如果从很远的有高级文明的星球发射到我们这儿，需要调节张角以达到照射地球的目的。
该文作者做了一个简单的计算，假如20光年之外的外星人建造一个能量为200 Tev的的缪子加速器，那么地球上正在建造的中微子探测器，如位于南极的IceCube，可以每年探测到10个左右事例。这些事例超过了宇宙射线造成的本底。
Another fundamental constant accused of changing
Cosmologists claim to have found evidence that yet another fundamental constant of nature, called mu, may have changed over the last 12 billion years. If confirmed, the result could force some physicists to radically rethink their theories. It would also provide support for string theory, which predicts extra spatial dimensions.
Distant quasars
Researchers at the Free University in Amsterdam in the Netherlands and the European Southern Observatory in Chile discovered the variation in mu. They did it by comparing the spectrum of molecular hydrogen gas in the laboratory to what it was in quasars 12 billion light years away. The spectrum depends on the relative masses of protons and electrons in the molecule.
“We concluded that the proton-electron mass ratio may have decreased by 0.002% in the past 12 billion years,” says team member Wim Ubachs.
“This claimed result is very interesting if true,” says Thibault Damour at the Institute of Advanced Scientific Studies (IHES) in Bures-sur-Yvette in France, who co-authored a 1996 paper that found no change in the fine structure constant, alpha.
Any change in mu, would support theories that posit extra dimensions. As these dimensions evolve, in a manner similar to our expanding 3D universe, the so-called constants would vary over both space and time. Or it may be that we still do not fully understand the proton: it may itself evolve through the universe’s lifetime, leading to the observed variation.
Ice-bound neutrino hunter may bolster string theory
Future neutrino experiments at the South Pole may be able to detect the predicted effects of string theory or other exotic phenomena, a new study suggests.
Gravity spill
Anchordoqui and his colleagues say cosmic neutrinos can achieve the energies needed when they slam into atoms on Earth. If gravity is hiding in the posited unseen dimensions, such collisions could open a floodgate between the dimensions and theoretically produce microscopic black holes that exist for just a fraction of a second before decaying into other particles.
The team says IceCube may be able to detect such black holes, or other exotic phenomena. It can measure neutrinos that have first passed through the Earth – "up" neutrinos – as well as those that simply fall to the detector from the sky – "down" neutrinos.
If cosmic neutrinos produce these fleeting, mini-black holes, IceCube should detect fewer "up" events than "down" events because the creation of black holes inside the Earth would prevent the neutrinos from reaching the detector.
Definitive effect
Team member Haim Goldberg of Northeastern University says the effect should be relatively easy to detect because neutrinos normally interact so weakly with matter. Any indication of a high-energy cosmic neutrino collision would signal something new.
John Schwarz, a string theorist at the California Institute of Technology in Pasadena, US, agrees. "If something non-standard is established, string theory has a long list of exotica that would provide candidates to explain it," he told New Scientist. "Experiments like those of IceCube and AMANDA-II are very challenging, so it would probably take several years of hard and careful work to achieve definitive results."
Goldberg estimates IceCube could begin taking data around 2008. Depending on the rate of cosmic neutrinos it detects, the experiment may be able to reveal new physical phenomena in as few as two years, or as many as 15.
Journal reference: Physical Review Letters (vol 96, p 021101)
When a neutrino collides with a water molecule deep in Antarctica’s ice, the particle it produces radiates a blue light called Cerenkov radiation, which IceCube will detect (Steve Yunck/NSF)
当国人在为我们的体育水立方沾沾自喜时，他人却在用科学冰立方苦苦寻找更加广阔的空间—额外空间维！
最新的WMAP数据找到了单场暴胀大爆炸理论的冒烟的枪—直接证据!
Pictures: NASA/JPL 2006-4-20
Cosmic Microwave Background （宇宙微波背景—astro-ph/0603449）
这是一幅极早期宇宙的最新的、更加详细的图。 微波颜色指 "更热" (红) 和 "更冷" (蓝) 的点—-比值为温度 （量子）涨落。白色线条表示最古老光线的"偏振"方向—-为右旋—-这是暴胀的最直接证据—-尤其是单场暴胀理论 (astro-ph/0604136)—-AdS非对易暴胀！ 这些新信息能帮助我们更精确的理解星系的形成和为理解暴胀的本质提供了最新的线索。
The new image of the cosmic microwave background is also a giant step closer to seeing "time-zero" — the moment the Universe began。
‘‘It’s giving us our first clues about how inflation took place,’’ said Michael Turner
The remarkable view comes from the best-ever picture of early light, seen in the form of faint microwaves, unveiled today, and confirms the inflationary "Big Bang" theory of how the universe began, as well as why galaxies exist.
"We have new evidence that the Universe went from microscopic to astronomical in the wink of an eye," announced Charles Bennett.
我们希望用弦理论来理解暴胀的机制—AdS(4) x S(5) = L(s)—-单场非对易暴胀!
摘自陈家忠BLOG
弦理论的确无与伦比地美，但是当前它所面临的首要问题是人们如何用实验与观测来证实或否定它。一个理论再美妙，它总得要回到现实世界来，不论在理论上，还是实验上；时下流行的版本这两方面都不如人意。但我敢的打赌弦理论中D-膜、超对称和对偶等思想是不可能错的，只是目前的版本需要升级—它严重地缺乏动力学，尤其是宇宙动力学演化。要求一个还在成长中的理论来解释一切，就像要求一个小孩做大人做的事一样，更何况一个理论的价值在很大一定程度上取决于它是否给人予新的思想和开拓人们的视野—这点弦理论已经做得足够了，比如它对数学的影响。关于弦理论的证据，可能来自两个方面，一是地面上的加速器和实验室 （诸如LHC、TEVTRON和引力偏离牛顿平方反比实验），一是宇宙学观测 （Hubble望远镜、Planck卫星、WMAP和LIGO等等）。这里整理了一些我感兴趣的弦理论的实验与观测证据，只是很少一部分。其他的以后慢慢补充。
Hubble explodes latest ‘evidence’ of cosmic strings—- that the big bang was the result of a collision between our universe and another 3D brane ,The collision of tow 3-branes would have given rise to one-dimensional cosmic strings—–F-strings.But Hubble bolsters the cosmic string—-D-strings.
In 2003, a team led by Mikhail Sazhin of the Sternberg Astronomical Institute in Moscow discovered two distant elliptical galaxies just a whisker apart. Detailed analysis of the twins, known as CSL-1, suggested that these were images of the same galaxy.
The team suggested that the duplicate images were being created by a "cosmic string" – a gigantic counterpart of the entities that string theory proposes give rise to the fundamental particles of matter.
Finding such a string would strengthen string theory and provide supporting evidence for the existence of the extra dimensions embodied in it. If one of these cosmic strings were to pass between Earth and a distant galaxy, the warping of space-time by the string would create a gravitational lens and form two identical images of the galaxy – exactly like CSL-1 (New Scientist, 30 July 2005, p 12).
Unfortunately for the proponents of cosmic strings, observations with Hubble on 12 January have revealed that CSL-1 is actually two different galaxies. "We have to conclude that CSL-1 is not the lensing of an elliptical galaxy by a cosmic string," Sazhin says.
But Hubble bolsters the cosmic string—-D-strings.
The case for the existence of cosmic strings has received recent support from research, undertaken by Capodimonte Astronomical Observatory, Naples, and the Sternberg Astronomical Institute, Moscow, which supports the idea that these one-dimensional threads of energy, that can span millions of light years, could be the first sign of extra dimensions in the universe.
The idea could also be investigated here on Earth. The energies of the strings envisaged by Vachaspati are within the range of Europe’s Large Hadron Collider being built near Geneva, Switzerland, and hence could possibly be created by the particle accelerator. "We think the strings could be studied by the LHC when it becomes operational in 2007,
How 3D space survived
In one interpretation of string theory, called braneworld, those extra dimensions are large, perhaps even infinite, and our universe is just a 3D membrane drifting in a higher-dimensional space. However, that does not explain why our "brane" has three rather than, say, four or seven dimensions. 这种无超对称的膜世界理论有实验困难，它的量子引力能标在 TeV附近，但是最新的实验要求量子引力能标比 TeV 能标大十三个量级。问题主要出在无超对称上。所以我们需要超对称下的膜世界，还需解释我们为何生活在3膜中，而不是4膜或9膜等。
哈佛的Abraham Loeb教授根据最新观测数据声称 (astro-ph/0604242)，宇宙学常数的人择平均值比我们观测到的大3个量级，从而人择原理在99.9 %置信度上被排除了。C. Vafa (hep-th/0509212)和M. Douglas (Talk give in Strings 2005, Toronto)等人建议用swampland淹（阉）掉landscape。
Imagine a car windshield that displays a map to your destination, military goggles with targets and instructions displayed right before a soldier’s eyes or a billboard that doubles as a window.
Only in science fiction you say? Northwestern University researchers report that by combining organic and inorganic materials they have produced transparent, high-performance transistors that can be assembled inexpensively on both glass and plastics.
The results of this breakthrough, which brings such futuristic high-quality displays closer to reality, were published in the November 2006 issue of the journal Nature Materials.
Researchers have long worked on developing new types of displays powered by electronics without visible wires. But, until now, no one was able to develop materials for transistors that could be "invisible" while still maintaining a high level of performance.
"Our development provides new strategies for creating transparent electronics," said Tobin J. Marks, the Vladimir N. Ipatieff Research Professor in Chemistry in the Weinberg College of Arts and Sciences at Northwestern and professor of materials science and engineering, who led the research. "You can imagine a variety of applications for new electronics that haven’t been possible previously — imagine displays of text or images that would seem to be floating in space."
Transistors are used for all the switching and computing necessary in electronics, and, in displays, they are used to power and switch the light sources.
High-performance, transparent transistors could be combined with existing kinds of light display technologies, such as organic light-emitting diodes, liquid crystal displays (LCDs) and electroluminescent displays, which are already used in televisions, desktop and laptop computers and cell phones.
To create their thin-film transistors, Marks’ group combined films of the inorganic semiconductor indium oxide with a multilayer of self-assembling organic molecules that provides superior insulating properties.
The indium oxide films can be fabricated at room temperature, allowing the transistors to be produced at a low cost. And, in addition to being transparent, the transistors outperform the silicon transistors currently used in LCD screens and perform nearly as well as high-end polysilicon transistors.
Prototype displays using the transistors developed at Northwestern could be available in 12 to 18 months, said Marks. He has formed a start-up company, Polyera, to bring this and related technologies to market.
Source: Northwestern University
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