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主题：【原创】宇宙学的终结 -- 苏萸
家园 【原创】宇宙学的终结 【本文是部分科学家观点，主要假设了平直宇宙以及宇宙学常数随时间变化缓慢。】
从大爆炸开始，宇宙一直长大。
十年来观测到宇宙正在加速膨胀，除了物质之外，我们还需要黑暗的力量。
它就是暗能量，一种未知的能量密度，爱因斯坦的宇宙学常数。
当宇宙膨胀时，物质密度降低了，它自岿然不动。
不管开始有多少，它总有一天成为主导。事实上，现在，它占74%，物质才26%。
明天呢？它会更多，宇宙也会更加速的膨胀。
甚至快到远远超过光速。
假设我们现在的可见宇宙中有1万亿个星系。远处的它们离开得这么快，光再也来不及传到我们这，也就是说，它们永远的从我们的宇宙中消失了。我们拥有着前所未有的庞大的可见宇宙，却只能看到9千亿个星系，8千亿个。。越来越少。。
而近处的星系呢，它们之间的引力胜过宇宙膨胀的影响，它们将会聚，10个变8个，变5个，直到只有一个。
所以在可预见的将来，也许几千亿年之后，可见宇宙的中心是个巨大的星系团，而之外，除了极少的流浪者，是更加硕大的真空。远处的光正在传来，可是永远也到达不了。
褒姒等不到诸侯，西施浣纱不见小鱼儿，贵妃吃不到荔枝，貂蝉不知月全食，文成到不了香格里拉。
整个宇宙，成为孤岛的集合。
而宇宙学也就不存在了。
因为再也不会看到我们现在看到的一切。背景辐射的波长超出了当时可见宇宙的大小，观测原初核合成需要的星际物质不再可见。等等。
质子也不知道是不是已经衰变了。。
大爆炸？天文圣经中有传说，但我们从来没看到过任何痕迹，也不相信神迹。
Thomas Kuhn在他的被社会学家广为传唱的《The Structure of Scientific Revolutions》中详细讨论了scientific paradigms的shift，我相信他，还有绝大多数人从来没有想到，一门成熟科学的终结，竟然是因为这个对象再也不可测量了。
确实我们知道很多东西已经或正在消失，比如暴涨抹平其之前的信息，黑洞吞噬进入的信息，量子测量只选择叠加态中的某一个，但是，作为可见宇宙的整体，这样的事情也发生就实在让人气馁。我们现在意气风发的要看的更多更远，我们的知识在累积在修正，在通向终极真理，如果它存在的话；而若干年后，姑且不谈是否有生命在继承这些知识，这些知识本身就变的不可证明也无法证否，更要命的是，完全无用。
宇宙学就象某个桃花源，曾经快乐的生活过，然后全然的消失了。
参见
scientific american march 2008
元宝推荐：爱莲,家园 看不懂也要花~ 家园 写得不错，花一个 我挺喜欢这篇文章的风格，把复杂的想法很简洁地表达出来，条理分明，没有晦涩的词汇，再加上一些文学性的描述，短短的文章就使人印象深刻，
在我的印象中，宇宙学是现代科学中最接近“玄学”的东西，有点象古希腊时代人们对世界的探索，以很少的经验和验证手段去推测远在观察能力之外的东西，只能以各种假说来发散性的推测未知世界，现在翻回头来看古希腊时代的各种假说，不少假说都多多少少有些靠谱的成分。
现在的宇宙学大概面临着与古希腊哲学家同样的困境，几百亿光年之外和几百亿年之后的事，怎么去验证呀?只能以现有的知识为基础，提出各种假说（就是各种宇宙学模型）发散性的去推测未知宇宙，假说提出的越多，覆盖的范围就越大，命中的概率就越大。假说之间互相竞争，互相启发，可以促进宇宙学的发展。
这个特点使宇宙学与许多其它其它学科稍显不同，有人说过，古希腊时期的科学实际上是“智慧”，以逻辑推理来解释世界；只有在伽利略之后，科学才正式走入实证时代，从此，“通过试验发现现象->建立模型解释现象->通过试验来验证模型”这种模式成了科学发展的标准模式，宇宙学也不例外，只是由于一些事情无法验证，以至停留在模型阶段的时间就特别长，各种模型相持不下，以所以与其它学科相比，有点接近古希腊时期的“智慧”，正是由于这种情况，我想我们还是善待各种假说模型（前提是模型应以经过证实的知识为基础），每一种假说的提出，都使宇宙学的研究更加精彩，都使我们对宇宙的探索增加一份力量。
刚刚看到这个帖子，忍不住说几句，蚂蚁老大如觉不妥，请删。
家园 那讨论就请在这里打住吧。 虽然没有冻结帖子讨论的工具，但大家就默认是冻结了。可好？
家园 西西河不是天文论坛,请楼主 请楼主将你的文章发表在国内的天文爱好者网站,并接受那里业余和专业的天文工作者评价.
国内目前理论探索比较专业的,有上海网上天文台主办的天之文论坛.
http://www.astron.sh.cn/cgi-bin/leobbs.cgi
请注册后登陆到天文知识版块.那里有Shea,汤海明等斑竹坛主管理,不仅接受天文爱好者的原创文章,也接受民科人士的文章(对民科有个简单的测验).
某已无力继续作为天文爱好者活动.为西西河容易为各种"理论"所引导的思想活跃的许多河友计,请首先在那边讨论,有了共识再来科普不迟.
家园 宇宙膨胀‘超光速’不是民科，也不是争议话题，而是事实 楼上不妨先充实一下自己的天文学知识。
所谓宇宙膨胀‘超光速’，可以说是，也可以说不是，更保守的说---it depends。这不是因为学界对宇宙膨胀速度有争议，而是因为这句话没有包含足够清晰的物理学定义，可以作出模棱两可的理解，从而得出不同的答案。这不是错误，而是不够严谨。
楼主的介绍源自Scientific American的科普文章‘The End of Cosmology？’，内容基本忠于原文，最大的偏差恐怕是标题中少了个问号。
原文可以在此全文阅读：
如果你觉得我跟很多民科一样，都是不专业的，半懂不懂的，那倒也没错。可是这些结论并不来自于我。
以下科普资料分别来自NASA官方网站、UCLA天文系、Cornell天文系，请注意，这些都是科普问答而不是学术前沿的猜想。每段引言都有红字，这属于不同天文学家的不同说法，第一段与其他段落的红字说法似乎截然相反，但其实它们并没有冲突：
The Universe did not expand faster than light. The Universe was big enough 12 billion years ago that the light from some distant objects is only getting to us now. That doesn't mean that the Universe was more than 12 billion light years wide 12 billion years ago. Because we're moving away from the object, the light has had to catch up to us.Dr. Eric Christian
To imagine this situation think of the Universe as of a gigantic - maybe even infinitely large - dough of raisin bread. Scale your imagination down to a finite piece of dough, where you are sitting on a raisin in its center. The outer edge of the dough is equivalent to the edge of the "observable universe", from where we see the cosmic microwave background radiation. You have put a lot of yeast into your raisin bread, and you have set up microwave transmitters all around on the outer edge, blasting inward. Imagine that in reaction to this heating the dough rises at such a furious rate that the outer edge recedes from the center at almost the speed of light. Although the microwave transmitters were only at a relatively short distance at the beginning of this "gedankenexperiment" (thought experiment), the microwaves have to cross a much larger (continually growing) distance because of the ongoing expansion.I would like to add a cautionary note, in case you might be wondering. Don't get confused! This expansion does not violate Einstein's theory of relativity, even though the imaginary dough of the even larger Universe, which we can't see beyond that edge, appears to recede at speeds larger than the speed of light. The dough represents space itself, and in our expanding Universe space itself is expanding, carrying the galaxies (represented by the raisins) along on a ride. Einstein's limit to the speed of light applies only to motion through space, and not to expansion of space itself.
Dr. Eberhard Moebius
Can objects move away from us faster than the speed of light?Again, this is a question that depends on which of the many distance definitions one uses. However, if we assume that the distance of an object at time t is the distance from our position at time t to the object's position at time t measured by a set of observers moving with the expansion of the Universe, and all making their observations when they see the Universe as having age t, then the velocity (change in D per change in t) can definitely be larger than the speed of light. This is not a contradiction of special relativity because this distance is not the same as the spatial distance used in SR, and the age of the Universe is not the same as the time used in SR. In the special case of the empty Universe, where one can show the model in both special relativistic and cosmological coordinates, the velocity defined by change in cosmological distance per unit cosmic time is given by v = c ln(1+z), where z is the redshift, which clearly goes to infinity as the redshift goes to infinity, and is larger than c for z > 1.718. For the critical density Universe, this velocity is given by v = 2c[1-(1+z)-0.5] which is larger than c for z > 3 .
For the concordance model based on CMB data and the acceleration of the expansion measured using supernovae, a flat Universe with OmegaM = 0.27, the velocity is greater than c for z > 1.407.
Dr. Edward L. Wright
Some of the misunderstandings surrounding this topic might come from confusion over what is meant by the universe "expanding faster than the speed of light." However, for the simplest interpretation of your question, the answer is that the universe does expand faster than the speed of light, and, perhaps more surprisingly, some of the galaxies we can see right now are currently moving away from us faster than the speed of light! As a consequence of their great speeds, these galaxies will likely not be visible to us forever; some of them are right now emitting their last bit of light that will ever be able to make it all the way across space and reach us (billions of years from now). After that, we will observe them to freeze and fade, never to be heard from again.Dr. Dave Rothstein
What happens to a substance if its speed is more than the speed of light?We do not know what happens to a substance if it moves faster than the speed of light for the very simple reason that it can never move faster than the speed of light. The speed of light poses a fundamental limit to the speed that an object can take, relative to objects nearby it. In fact, no object with any finite rest mass can move at the speed of light. That is why all the particles that move at the speed of light (e.g. photons) have zero rest mass. As a particle with mass approaches the speed of light, its energy increases and becomes infinite at the speed of light, which is the reason why it can never be accelerated to reach that speed. This has actually been verified by experiments, and it has been shown that nothing moves faster than the speed of light.
However, the above discussion only applies to objects on small scales in the universe -- for example, if you take a baseball or a planet or a star or a galaxy and try to accelerate these objects to the speed of light relative to objects nearby them, it is impossible to do. However, there is nothing which prevents objects that are separated by huge distances from moving relative to each other faster than the speed of light. Over these large distances, the effects of the universe's expansion become important, and the above discussion no longer applies.
Dr. Jagadheep D. Pandian
家园 我看还不能算事实。 谁也没法去具体测一下，哪怕是间接测量。
这只是根据现在观测到的现象和物理知识倒推出来的，如果这些中间有一个有还没发现的缺陷，这个结论就是错误的。
当然，运动不可能超光速也有可能是错的。
家园 请把我跟萨佛的讨论看下去 谁也没法去具体测一下，哪怕是间接测量。这只是根据现在观测到的现象和物理知识倒推出来的，如果这些中间有一个有还没发现的缺陷，这个结论就是错误的。
什么叫具体测量？眼见为实？我们用显微镜看到质子电子中子了吗？还不是靠理论与使用各种间接手段的实验推断出来。
宇宙膨胀（并在一定距离上超光速）对现在的宇宙学来说就是个常识，而且是宇宙模型的基石之一，您别以为这只是一小群人前沿猜想。对哈勃常数（宇宙膨胀速度）的测量可是进行了好几十年了，描述宇宙膨胀的哈勃定律本身就是哈勃通过数十年的观察总结出来的，并在接下来的几十年中获得了所有天文观测与实验结果的支持。
当然，运动不可能超光速也有可能是错的。宇宙膨胀是空间的膨胀，这跟物体运动超光速是两回事，与广义相对论更是完全没有冲突。
家园 谢谢!花.虽然由于英文水平限制,还要多花时间读 专家大致都是说"看起来"超光速并不等于宇宙膨胀确实超过了光速.
我对楼主文章的怀疑,是那句"宇宙膨胀远远超过了光速".专家们的意思不会是膨胀超过光速吧?
家园 大致学了科学美国人2008-3那文章.感觉属哲学讨论 文章挺长.网页5页,打印A4纸估计要更多点.
那文章几处说,未来宇宙膨胀之后,新的文明由他们自己的太阳系的引力发现广义相对论,但会如何如何......
基本是探讨宇宙膨胀使得遥远部分对"我们的"星系群的速度超过光速会发生什么,如不再可见等.
似乎不是从科学角度谈的.
如果从科学角度看,我们发现宇宙膨胀是通过红移,是否有红移达到超短波的观测报告,就能判断遥远天体是否已经出现相当接近光速的情况.当然若能有办法发现移动到长波的就更有说服力.因为有超过光速的对象,也就应该有接近光速的对象.更低频率的电磁波如何接收和判读需要等待技术开发的相应成果.
另外,大爆炸的余辉随宇宙膨胀的频谱变化和强度变化,若遥远空间离开我们的速度接近以至达到和超过光速,那部分空间的大爆炸余辉传来的频谱该如何,也在讨论范围吧?
还有中微子的行为应显示什么状态,遥远空间的噶玛射线暴会否在我们这里红移成可见光新星或超新星样.许多要观测判断的事物需要与这所谓"科学事实"相呼应.
PS:卷心菜河友给的几个链接,水平所限没有全看懂,但是也感觉到是在描述场景,并没有介绍什么相关的科学证据.
另外昨天看到本版块年初有河友发的天文科普系列帖,其中提到了"2000年哈勃望远镜观测到260亿光年外天体"的说法,大惊,忙用谷歌和NASA自己网站的搜索工具搜了"26 billion light-years"条目,结果基本无所获.特别是NASA自己居然没有此对应结果.若作者看了本帖,还请修正为妥.或者删除相应帖子内容.所谓"惊世骇俗的结论需要有惊世骇俗的证据支持",8年那消息都没有震动天文界,也没有后续的报道,其真实性是否该核计核计呢?
家园 非科学角度的哲学讨论？ 这个说法恐怕有些过了，原文明明提到了很多科学发现，大段大段地叙述了近年宇宙学的发展，虽然没有详细介绍各种发现的具体过程与内容（主题不在于此），但文章的推断很明显是基于这些发现，而非形而上的哲学思维。只要认真地看看其内容，再对比一下宇宙学的最新发现，就不难看出这点。
那篇文章基本上是根据已知最新证据作出一种猜想（文章并不否认这点，看标题就知道）。须知我们对宇宙模型的建立还处于非常初步的阶段，比如说‘宇宙扩张在加速’这一点，距离发现充分证据并被广泛接受至今还不到十年，所谓暗物质也还停留在理论猜测的阶段。以后我们会不会得出新的、与现有结论相冲突的发现？有这种可能。但这并不妨碍我们基于现有的认知作出合理推测，不然科学如何进步？
随手截取几段：
Our own experience demonstrates that even when we have data, the correct cosmological model is not so obvious. For example, from the 1940s to the mid-1960s, with the edifice of observational cosmology resting only on Hubble’s discovery of the expanding universe, some astrophysicists resurrected the idea of an eternal universe: the steady-state universe, in which matter is created as the universe expands, so that the universe as a whole does not really change with time. This idea proved to be an intellectual dead end, but it does demonstrate the kind of mistaken notion that can develop in the absence of adequate observational data.Where else might astronomers of the future search for evidence of the big bang? Would the cosmic microwave background allow them to probe the dynamics of the universe? Alas, no. As the universe expands, the wavelengths of the background radiation stretch and the radiation becomes more diffuse. When the universe is 100 billion years old, the peak wavelengths of the microwave radiation will be on the scale of meters, corresponding to radio waves instead of microwaves. The intensity of the radiation will be diluted by a factor of one trillion and might never be seen.
Even further into the future, the cosmic background will become truly unobservable. The space between stars in our galaxy is filled with an ionized gas of electrons. Low-frequency radio waves cannot penetrate such a gas; they are absorbed or reflected. A similar effect is the reason that AM radio stations can be picked up far from their cities of origin at night; the radio waves reflect off the ionosphere and back down to the ground. The interstellar medium can be thought of as one big ionosphere filling the galaxy. Any radio waves with frequencies below about one kilohertz (a wavelength of greater than 300 kilometers) cannot penetrate into our galaxy. Radio astronomy below one kilohertz is forever impossible inside our galaxy. When the universe is about 25 times its present age, the microwave background will be stretched beyond this wavelength and become undetectable to the residents of the galaxy. Even before then, the subtle patterns in this background radiation, which have provided so much useful information to today’s cosmologists, will become too muted to study.
你在提出疑义之前，有没有认真理解原文的内容呢？如有语言障碍，具体不清楚的地方我可以尝试帮你翻译。当然，在专业知识方面我也是个半桶水，就不要期望太高了。
家园 请看您引用的英文部分 说的大体是千亿年后,宇宙背景辐射频率降低到了短波波段,强度被稀释到了百万分之一,于是不再可见;星际充斥电子的电离气体云(?),于是被当作整个宇宙的性状.到宇宙达到现年龄的25倍时,背景辐射就不能传播了.这样大爆炸就极难被发现了.
其实,这里也没有真正涉及超过光速离开我们的那部分空间所存在的宇宙背景辐射问题,因此那估算似乎不很完备.
更何况,楼主的中文帖子内容并不是讨论类似上述内容的,而是基于原文部分结论的感叹.
科学研究的对象是客观存在的,可被重复测量的事物.大爆炸理论能否为千亿年甚至三千多亿年以后的观察者再次发现,我们现在手里的资料太少难于判断,就是能判断也不过是一种有根据的推测,不能归类于科研范畴的,宜乎作为哲学看待.