Two of the Universe’s Great Mysteries May Have Their Own Dimension

宇宙两大未解之谜或许拥有属于它们自己的维度

For those who see the world as a dark place, the universe seems to offer little solace. According to current estimates, approximately 70 percent of the stuff that makes up the cosmos consists of dark energy, an unknown force that pushes space to expand. And another 25 percent consists of dark matter, a mysterious material that holds galaxies together. 对于那些认为世界是黑暗之地的人来说，宇宙似乎也提供不了多少慰藉。根据目前的估计，构成宇宙的物质中约有 70% 是暗能量，这是一种推动空间膨胀的未知力量。另外 25% 是暗物质，这是一种将星系维系在一起的神秘物质。

But semantically speaking, dark energy and dark matter are not so much “dark” as they are invisible. They do not emit, reflect, nor absorb light, and they have so far proven impossible to observe directly. 但从语义上讲，暗能量和暗物质与其说是“暗”，不如说是“隐形”。它们既不发射、反射也不吸收光线，迄今为止，人类还无法直接观测到它们。

Generally, dark energy and dark matter are regarded as separate entities, their elusiveness their primary link. But recent astronomical observations have spurred scientists to look further into a less popular idea—that the two are in fact physically intertwined. 通常，暗能量和暗物质被视为独立的实体，它们唯一的共同点就是难以捉摸。但近期的天文观测促使科学家们深入研究一个此前不太受关注的观点——即这两者在物理上实际上是相互交织的。

In 2024, the research team known as DESI, for Dark Energy Spectroscopic Instrument, found evidence that the strength of dark energy, sometimes referred to as the “cosmological constant,” had lost its presumed constancy. A 2025 study based on more than twice as much data also concluded that dark energy was changing over time. 2024 年，名为 DESI（暗能量光谱仪）的研究团队发现证据表明，暗能量的强度（有时被称为“宇宙学常数”）失去了其预想中的恒定性。2025 年一项基于两倍多数据量的研究也得出结论：暗能量随时间在发生变化。

These results indicate that after attaining a maximum value about 2 billion years ago, dark energy may have begun to weaken. But the results also suggested that in an earlier era, dark energy could have grown stronger, in seeming defiance of the law of energy conservation. 这些结果表明，暗能量在约 20 亿年前达到最大值后，可能已经开始减弱。但结果同时也暗示，在更早的时期，暗能量可能曾变得更强，这似乎违背了能量守恒定律。

Researchers describe this as dark energy entering the “phantom regime.” They liken the situation to a ball rolling uphill. It’s certainly possible, but only if the ball is under the influence of something other than gravity. 研究人员将此描述为暗能量进入了“幻影状态”（phantom regime）。他们将这种情况比作一个球向上滚动。这当然是有可能的，但前提是该球受到了重力以外的其他因素影响。

A growing number of theorists are looking into the possibility that what’s influencing dark energy are its ties to dark matter. 越来越多的理论物理学家开始研究这种可能性：影响暗能量的因素正是它与暗物质之间的联系。

Even though scientists have assumed that dark energy and dark matter “don’t have anything to do with each other,” said Tim Tait, a particle physicist at the University of California, Irvine, “you can imagine a case where one influences the other. And it would not be surprising if [they] were manifestations of a kind of unified theory of the dark universe.” 加州大学欧文分校的粒子物理学家蒂姆·泰特（Tim Tait）表示，尽管科学家们一直假设暗能量和暗物质“互不相关”，“但你可以想象一种两者相互影响的情况。如果它们是某种暗宇宙统一理论的表现形式，那也不足为奇。”

Dark Interactions

暗相互作用

The idea that dark energy and dark matter interact is not new. For example, Justin Khoury, a physicist at the University of Pennsylvania, investigated the prospect in 2005. 暗能量与暗物质相互作用的观点并不新鲜。例如，宾夕法尼亚大学的物理学家贾斯汀·库里（Justin Khoury）曾在 2005 年研究过这一前景。

Khoury explained that in that study, he and two coauthors posed a hypothetical question: Could there be a form of dark energy whose energy density increased over time? He and his collaborators found that if dark energy and dark matter could affect one another, they could produce what looked like (but was not) phantom behavior. “It is the most natural, simplest way of achieving this,” Khoury said. 库里解释说，在那项研究中，他和两位合著者提出了一个假设性问题：是否存在一种能量密度随时间增加的暗能量？他和合作者发现，如果暗能量和暗物质能够相互影响，它们就能产生看起来像（但实际上并非）幻影行为的现象。“这是实现这一目标最自然、最简单的方法，”库里说。

Two decades later came the DESI finding that dark energy might actually be changing over time. The result spurred Khoury and two Pennsylvania colleagues, Meng-Xiang Lin and Mark Trodden, to construct a model of dark interactions based on a dark-sector analogue of quantum chromodynamics, a cornerstone theory of particle physics. In the new model, both the energy density of dark energy and the mass of dark matter change in concert. 二十年后，DESI 的发现证实暗能量确实可能随时间发生变化。这一结果促使库里和他在宾夕法尼亚大学的同事林孟祥（Meng-Xiang Lin）及马克·特罗登（Mark Trodden）构建了一个暗相互作用模型，该模型基于粒子物理学基石理论——量子色动力学的暗区模拟。在这个新模型中，暗能量的能量密度和暗物质的质量是协同变化的。

Another recent study imagines something similar. According to this model, which was published in January in the journal Physical Review D, dark matter could have transferred a small fraction of its energy to dark energy during a previous era of cosmic history. “Dark matter is the main brake on [the universe’s] expansion,” said one of the authors, Elsa Teixeira, a cosmologist at the University of Montpellier in France, so easing up on that brake would have caused the expansion of the universe to accelerate. 另一项近期研究也设想了类似的情况。根据今年 1 月发表在《物理评论 D》期刊上的模型，暗物质可能在宇宙历史的早期阶段将其一小部分能量转移给了暗能量。该论文作者之一、法国蒙彼利埃大学的宇宙学家埃尔莎·特谢拉（Elsa Teixeira）表示：“暗物质是（宇宙）膨胀的主要刹车，因此放松这个刹车会导致宇宙膨胀加速。”

The appearance of phantom behavior is basically the result of bookkeeping, said David Andriot, a physicist at CNRS, the French National Center for Scientific Research. “Any change or evolution of the mass of dark matter has been put into the box of dark energy,” said Andriot, who presented his own coupled dark energy-dark matter model in May 2025. 法国国家科学研究中心（CNRS）的物理学家大卫·安德里奥特（David Andriot）表示，幻影行为的出现基本上是“记账”的结果。安德里奥特在 2025 年 5 月提出了他自己的暗能量-暗物质耦合模型，他说：“暗物质质量的任何变化或演变都被归入了暗能量的范畴。”

Cumrun Vafa, a physicist at Harvard University, agreed. “The notion that you can compute dark energy independently of dark matter is wrong,” he said. “That assumption, often made by cosmologists and also followed by the DESI team, led to the physically unacceptable phantom behavior.” 哈佛大学物理学家卡姆伦·瓦法（Cumrun Vafa）对此表示赞同。他说：“认为可以独立于暗物质来计算暗能量的想法是错误的。这种宇宙学家经常做出、且 DESI 团队也遵循的假设，导致了物理上不可接受的幻影行为。”

The DESI findings are not the only reason to consider an association between dark energy and dark matter. Teixeira and colleagues’ recent study shows how allowing the two to interact can, at least in some scenarios, ameliorate one of the most persistent problems in cosmology: the Hubble tension. DESI 的发现并不是考虑暗能量与暗物质之间存在关联的唯一理由。特谢拉及其同事近期的研究表明，允许两者相互作用，至少在某些情况下，可以缓解宇宙学中最顽固的问题之一：哈勃张力（Hubble tension）。

At issue is the current expansion rate of the universe, known as the Hubble constant. Its value can be measured by using light from the early universe, which provides a view of how the cosmos was growing in its earliest days. It can also be measured by drawing upon more recent phenomena, such as exploding stars called supernovas, which reveal how the universe is growing now. 问题的核心是宇宙当前的膨胀率，即哈勃常数。其数值可以通过利用来自早期宇宙的光来测量，这提供了宇宙在诞生之初如何增长的视角。它也可以通过利用更近期的现象来测量，例如被称为超新星的恒星爆炸，这些现象揭示了宇宙现在是如何增长的。

According to the standard model of cosmology, that expansion rate should be the same no matter how you measure it. But in recent years, scientists have found that the expansion rate of the early universe and that of the more recent universe vary by approximately 9 percent. 根据宇宙学标准模型，无论用什么方法测量，该膨胀率都应该是相同的。但近年来，科学家们发现早期宇宙的膨胀率与近期宇宙的膨胀率存在约 9% 的差异。

That discrepancy, or tension, “has provoked heated debates in the cosmology community about whether this difference could 这种差异（即张力）“在宇宙学界引发了激烈的争论，讨论这种差异是否可能……”