What if the Universe Isn’t as Uniform as Scientists Think?
What if the Universe Isn’t as Uniform as Scientists Think?
如果宇宙并不像科学家认为的那样均匀，会怎样？
One of the fundamental pillars of modern cosmology may be beginning to wobble. A study published in Nature has found evidence that the universe may not behave the same way in every direction on the largest observable scales. 现代宇宙学的基本支柱之一可能开始动摇了。发表在《自然》杂志上的一项研究发现，在可观测的最大尺度上，宇宙在各个方向上的表现可能并不一致。
“What we found is a network of enormous filaments and walls of galaxies that remain aligned and interconnected across billions of light-years,” says Francesco Sylos Labini, research director of physics at the Enrico Fermi Research Center in Italy and the study’s lead author. “我们发现了一个由巨大的星系纤维和星系墙组成的网络，它们在数十亿光年的范围内保持着排列和互联，”意大利恩里科·费米研究中心物理学研究主任、该研究的主要作者弗朗切斯科·赛洛斯·拉比尼（Francesco Sylos Labini）说。
What Should the Universe Look Like?
宇宙应该是什么样子的？
To explain the finding, Sylos uses a far simpler analogy than any mathematical equation. Imagine a map of the universe in which every galaxy is represented by a single point. If the universe truly becomes uniform on the largest scales, he explains, there should come a point at which the map looks essentially the same in every direction. Like a photograph viewed from a great distance, its details would gradually blur together until only a nearly uniform background remained. 为了解释这一发现，赛洛斯使用了一个比任何数学方程都简单的类比。想象一张宇宙地图，其中每个星系都用一个点来表示。他解释说，如果宇宙在最大尺度上确实变得均匀，那么应该存在一个临界点，使得地图在各个方向上看起来基本相同。就像从远处观看一张照片，其细节会逐渐模糊，直到只剩下一个近乎均匀的背景。
But that is not what Sylos and his colleague Marco Galoppo found. 但赛洛斯和他的同事马可·加洛波（Marco Galoppo）发现的情况并非如此。
“The idea that the universe becomes statistically uniform on sufficiently large scales is what allows us to describe it using relatively simple mathematical models,” Sylos says. Their observations, however, suggest that the real universe may remain more structured and directionally organized than this picture assumes. “认为宇宙在足够大的尺度上变得统计学均匀，这使我们能够使用相对简单的数学模型来描述它，”赛洛斯说。然而，他们的观测结果表明，真实的宇宙可能比这一模型所假设的更具结构性和方向性。
In other words, the organization of these vast cosmic networks does not disappear as increasingly larger regions of the universe are examined. Rather than gradually fading into a featureless background, the universe’s largest structures retain recognizable patterns even on scales where, according to the standard cosmological model, those patterns should no longer be detectable. 换句话说，随着对宇宙更大区域的考察，这些巨大的宇宙网络的组织结构并没有消失。宇宙中最大的结构并没有逐渐淡化为毫无特征的背景，即使在根据标准宇宙学模型本应无法探测到这些模式的尺度上，它们依然保留着可识别的模式。
No Cosmic Arrow but a Persistent Pattern
没有宇宙之箭，但有持续的模式
The researchers stress, however, that this finding requires an important qualification. It does not mean the universe has a single preferred axis or direction. 然而，研究人员强调，这一发现需要一个重要的限定条件。这并不意味着宇宙有一个单一的优先轴或方向。
“We are not claiming that the entire universe has one preferred direction, as though there were a cosmic arrow running through space,” Sylos says. “What we found is much more subtle.” “我们并不是声称整个宇宙有一个优先方向，仿佛有一支宇宙之箭穿过空间，”赛洛斯说。“我们发现的东西要微妙得多。”
(Image caption: A three-dimensional map of the universe constructed by the Dark Energy Spectroscopic Instrument based on the positions of millions of galaxies. The close-up shows the cosmic web of filaments and voids that connects the large-scale structures of the universe. Courtesy of ESI Collaboration/KPNO/NOIRLab/NSF/AURA/R. Proctor) （图片说明：由暗能量光谱仪根据数百万个星系的位置构建的宇宙三维地图。特写展示了连接宇宙大尺度结构的纤维和空洞组成的宇宙网。图片来源：ESI Collaboration/KPNO/NOIRLab/NSF/AURA/R. Proctor）
Instead, the team detected coherent patterns in the distribution of galaxies that persist over extraordinarily large distances. 相反，研究小组在星系分布中探测到了在极长距离上持续存在的连贯模式。
As the volume of the universe under observation increases, galaxies should eventually become indistinguishable from a uniform background, much like the blurred photograph in the earlier analogy. “Instead, as we expand our field of view, new coherent structures continue to emerge,” Sylos says. “Rather than converging toward uniformity, the cosmic web remains organized on progressively larger scales.” 随着观测宇宙体积的增加，星系最终应该变得与均匀背景无法区分，就像前面类比中模糊的照片一样。“相反，当我们扩大视野时，新的连贯结构不断出现，”赛洛斯说。“宇宙网并没有趋向于均匀，而是在越来越大的尺度上保持着组织性。”
The conclusion is the culmination of more than two decades of research. Since the early 2000s, Sylos has sought to answer a question that is rarely tested directly: how do we actually know that the universe becomes homogeneous and isotropic on sufficiently large scales? (An isotropic medium has the same physical properties in every direction.) 这一结论是二十多年研究的结晶。自21世纪初以来，赛洛斯一直试图回答一个很少被直接验证的问题：我们如何真正知道宇宙在足够大的尺度上变得均匀且各向同性？（各向同性介质在各个方向上具有相同的物理性质。）
As galaxy catalogs expanded over the years, astronomers also began discovering structures far larger than previously thought possible. This study represents the latest step in that line of research, introducing a new statistical method for measuring the universe’s large-scale structure. 随着多年来星系目录的扩展，天文学家也开始发现比以前认为的可能规模大得多的结构。这项研究代表了该研究方向的最新进展，引入了一种测量宇宙大尺度结构的新统计方法。
To test their hypothesis, the researchers analyzed the positions of nearly 47 million galaxies observed by the Dark Energy Spectroscopic Instrument, spanning roughly 11 billion years of cosmic history. Rather than simply searching for a preferred direction, they developed a new statistical technique capable of determining whether the orientations of millions of galaxy pairs retain coherent patterns even on scales approaching one gigaparsec—about 3.26 billion light-years. 为了验证他们的假设，研究人员分析了由暗能量光谱仪观测到的近4700万个星系的位置，跨越了大约110亿年的宇宙历史。他们没有简单地寻找一个优先方向，而是开发了一种新的统计技术，能够确定数百万对星系的取向是否在接近一吉秒差距（约32.6亿光年）的尺度上仍保持连贯的模式。
(Image caption: Artist’s rendering of the cosmic web. The bright filaments represent regions where most galaxies are concentrated, while the dark areas correspond to enormous cosmic voids. Courtesy of NASA’s Goddard Space Flight Center / Scientific Visualization Studio) （图片说明：宇宙网的艺术渲染图。明亮的纤维代表大多数星系集中的区域，而黑暗区域对应于巨大的宇宙空洞。图片来源：NASA戈达德太空飞行中心/科学可视化工作室）
If future observations confirm these results, cosmologists may need to reconsider how large-scale uniformity actually emerges and whether current models of dark matter, gravity, and structure formation fully describe the evolution of the universe. Before any claims of a scientific revolution can be made, however, the findings will need to be independently replicated using larger datasets, both with the authors’ methodology and with alternative approaches. 如果未来的观测证实了这些结果，宇宙学家可能需要重新思考大尺度均匀性是如何产生的，以及现有的暗物质、引力和结构形成模型是否能完全描述宇宙的演化。然而，在宣称科学革命之前，这些发现还需要使用更大的数据集，通过作者的方法以及其他替代方法进行独立验证。
“Ultimately, the question is not whether our paper is right or wrong,” Sylos says. “The question is whether nature is telling us something new about the universe on the largest scales. If future studies confirm our findings, they will point toward a more complete understanding of cosmic structure. If they do not, we will have learned something equally valuable about the limitations of our methods. Either way, science will have advanced.” “归根结底，问题不在于我们的论文是对是错，”赛洛斯说。“问题在于大自然是否在向我们揭示关于宇宙最大尺度的新信息。如果未来的研究证实了我们的发现，它们将指向对宇宙结构更完整的理解。如果不能，我们也同样会了解到我们方法论的局限性，这同样有价值。无论哪种方式，科学都将取得进步。”
This story originally appeared on WIRED en Español and has been translated from Spanish. 本文最初发表于《连线》西班牙语版，由西班牙语翻译而来。