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弦理论的实验与观测证据

时间:2011-01-05 19:22:16  来源:  作者:

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。

 

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.

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