Monster Neutrino Could Be a Messenger of Ancient Black Holes

Strings of optical modules like this make up the underwater KM3NET neutrino detector.

像这样的光学模块串组成了水下 KM3NET 中微子探测器。

Nearly three years ago, a particle from space slammed into the Mediterranean Sea and lit up the partially complete Cubic Kilometer Neutrino Telescope (KM3NET) detector off the coast of Sicily.

大约三年前，一颗来自太空的粒子撞击地中海，点亮了西西里岛海岸部分完整的立方千米中微子望远镜（KM3NET）探测器。

The particle was a neutrino, a fundamental component of matter commonly known for its ability to slip through other matter unnoticed.

该粒子是中微子，它是物质的基本组成部分，因其能够在不被注意的情况下穿过其他物质而闻名。

The IceCube observatory in Antarctica, a comparable detector that has been running for more than a decade, has found hundreds of cosmic neutrinos — but none quite like this one.

南极洲的冰立方天文台是一个类似的探测器，已经运行了十多年，已经发现了数百个宇宙中微子，但没有一个像这个一样。

Some 35 times more energetic than any neutrino seen before, the particle might have shot out from a highly active galaxy — a blazar — or a background source of cosmogenic high-energy particles that scientists suspect pervade the cosmos.

这种粒子的能量大约比以前见过的任何中微子高出 35 倍，它可能是从一个高度活跃的星系（耀变体）或科学家怀疑遍布宇宙的宇宙高能粒子的背景源中射出的。

But those aren’t the only possibilities.

但这些并不是唯一的可能性。

The day after the KM3NET collaboration announced the detection , the physicist David Kaiser walked into a room full of his colleagues at the Massachusetts Institute of Technology with a bold proposition: What if the monster neutrino came from an exploding primordial black hole?

KM3NET 合作组织宣布发现这一发现的第二天，物理学家 David Kaiser 走进麻省理工学院的一个满是同事的房间，提出了一个大胆的命题：如果这个巨大的中微子来自爆炸的原始黑洞怎么办？

Such black holes “could form before there were even atoms, let alone stars,” said Kaiser, who has been heavily involved in the hunt for these hypothetical objects.

凯撒说，这样的黑洞“甚至可能在原子出现之前就形成了，更不用说恒星了”，他一直积极参与寻找这些假设物体的活动。

The idea that the neutrino came from a primordial black hole is a long shot; Kaiser said he was “half-joking” when he suggested it.

认为中微子来自太初黑洞的想法是不可能的。凯撒表示，他提出这个建议时是“半开玩笑”的。

But in the absence of a definitive explanation, it remains intriguing, not least because the existence of primordial black holes could mean they play a role in dark matter.

但在缺乏明确解释的情况下，它仍然很有趣，尤其是因为原始黑洞的存在可能意味着它们在暗物质中发挥作用。

So the question is, did we just spot one?

所以问题是，我们刚刚发现了一个吗？

The idea of primordial black holes was first proposed in 1966 by the Soviet physicists Yakov Zel’dovich and Igor Novikov, and it was cemented by the British astrophysicist Stephen Hawking in 1971 .

原初黑洞的概念最早由苏联物理学家雅科夫·泽尔多维奇和伊戈尔·诺维科夫于1966年提出，并于1971年由英国天体物理学家斯蒂芬·霍金巩固。

Hawking and his student Bernard Carr , of Queen Mary University of London in the U.K., then worked out the concept of primordial black holes in detail in 1974 .

1974年，霍金和他的英国伦敦玛丽女王大学的学生伯纳德·卡尔详细提出了原初黑洞的概念。

A primordial black hole, or PBH, is loosely defined as a black hole that formed in the first split second of the universe.

原始黑洞（PBH）被宽泛地定义为在宇宙诞生的第一瞬间形成的黑洞。

The hypothesis goes that during the rapid expansion of space, there might have been spikes in the density of space-time that were so high that they would have collapsed into black holes.

该假设认为，在空间快速膨胀的过程中，时空密度可能会出现峰值，以至于它们会塌缩成黑洞。

These black holes would have spanned a range of masses, depending on the size of the spikes.

这些黑洞的质量范围取决于尖峰的大小。

Some could have been as small as an atomic nucleus.

有些可能像原子核一样小。

David Kaiser, a physicist at the Massachusetts Institute of Technology, is searching for evidence of primordial black holes.

麻省理工学院的物理学家大卫·凯泽正在寻找原始黑洞的证据。

The idea has its problems.

这个想法有其问题。

Incorporating PBHs into the early universe requires physicists to adjust the parameters of their models very precisely to fit with observations, said Wenzer Qin , a theoretical physicist at New York University.

纽约大学理论物理学家温泽·钦表示，将PBH纳入早期宇宙需要物理学家非常精确地调整模型参数以适应观测结果。

“You have to tune the knob just right,” she said.

“你必须把旋钮调到恰到好处，”她说。

“You need the density spikes to be 10,000 times larger than you would have predicted in standard cosmological theory.”

“你需要密度峰值比标准宇宙学理论预测的大 10,000 倍。”

The same year Hawking and Carr explained the concept of primordial black holes, Hawking also put forward his idea of Hawking radiation , a process in which black holes might lose mass and energy by emitting photons and other fundamental particles through the interaction of quantum physics and gravity at the black hole’s edge.

在霍金和卡尔解释了原初黑洞概念的同一年，霍金还提出了霍金辐射的想法，在这个过程中，黑洞通过量子物理和引力在黑洞边缘的相互作用发射光子和其他基本粒子，从而可能失去质量和能量。

Giving off Hawking radiation, a primordial black hole that was originally the size of an atomic nucleus would meet its doom in the modern universe, slowly dwindling before ending in a sudden, extreme burst of particles.

最初只有原子核大小的原始黑洞发出霍金辐射，将在现代宇宙中迎来它的灭亡，它会慢慢缩小，然后以突然的、极端的粒子爆发结束。

“Very little mass gets radiated over the majority of the black hole’s lifetime,” said Alexandra Klipfel, a doctoral student working with Kaiser on PBHs at MIT.

“在黑洞生命的大部分时间里，辐射出的质量非常小，”麻省理工学院与凯撒一起研究PBH的博士生亚历山德拉·克利普菲尔(Alexandra Klipfel)说。

“But then, right at the end, it emits a majority of its mass in a very rapid explosion.

“但是，就在最后，它在一次非常快速的爆炸中释放出了大部分质量。

It heats up really, really quickly, a runaway process that ends in a big explosion of ultra-high-energy particles.”

它升温得非常非常快，这是一个失控的过程，最终导致超高能粒子的大爆炸。”

That process occurs “because the temperature of the black hole is inversely proportional to the mass,” Klipfel said.

克利普费尔说，这个过程的发生“是因为黑洞的温度与质量成反比”。

“The lighter the mass, the hotter the temperature.”

“质量越轻，温度越高。”

Because the energy released in Hawking radiation doesn’t favor one type of particle over another, the final burst would include all 17 fundamental particles in the Standard Model, our benchmark model explaining the cosmos.

由于霍金辐射中释放的能量不会偏向某种类型的粒子，因此最终的爆发将包括标准模型（我们解释宇宙的基准模型）中的所有 17 种基本粒子。

In that moment, as the black hole was extinguished, trillions upon trillions of particles would explode into space, “including neutrinos and quarks and all kinds of exotic things,” Kaiser said.

在那一刻，随着黑洞的熄灭，数万亿的粒子将爆炸到太空中，“包括中微子、夸克和各种奇异的东西，”凯泽说。

Alexandra Klipfel co-wrote a paper about the possible origins of the powerful neutrino.

亚历山德拉·克利普费尔 (Alexandra Klipfel) 与人合写了一篇关于强中微子可能起源的论文。

The tiniest primordial black holes would have lasted only moments, but more massive ones could still be around.

最微小的原始黑洞只能持续片刻，但更大的黑洞可能仍然存在。

“A black hole with a mass of about 10 14 [100 trillion] grams has a lifetime equal to the age of the universe,” Klipfel said.

“质量约为 10 14 [100 万亿] 克的黑洞的寿命等于宇宙的年龄，”克利普费尔说。

Scientists have ruled out (or constrained) the possible masses of PBHs that could be hiding in the universe today.

科学家们已经排除（或限制）了当今宇宙中可能隐藏的PBH的可能质量。

Too small and the PBHs would have evaporated already.

如果太小，PBH 就会消失。

Too big and their gravitational effects would have been spotted warping the light coming to Earth from distant stars and galaxies.

如果太大，它们的引力效应就会扭曲从遥远恒星和星系到达地球的光线。

The best window left for most PBHs, it seems, ranges from about 100 quadrillion (10 17 ) grams — the mass of an average asteroid — to 100 sextillion (10 23 ) grams, the mass of a moon.

对于大多数PBH来说，最好的窗口范围似乎是从大约100千万亿（10 17 ）克（一颗普通小行星的质量）到100万亿（10 23 ）克（月球的质量）。

A smaller subpopulation of PBHs of 100 trillion (10 14 ) grams or lower, the mass of a small asteroid, would be in their final stages of evaporation.

一个较小的 PBH 亚群，其质量为 100 万亿 (10 14 ) 克或更低，相当于一颗小行星的质量，将处于蒸发的最后阶段。

If primordial black holes do exist in the asteroid-mass window, not only can they tell us about the conditions at the dawn of the cosmos, but they might also answer another open question in astrophysics.

如果小行星质量窗口中确实存在原始黑洞，它们不仅可以告诉我们宇宙黎明时的情况，而且还可能回答天体物理学中的另一个悬而未决的问题。

If they still exist in the present universe, they might constitute some or all of the missing mass we can infer in the rotation of galaxies and the structure of the cosmos that scientists more commonly link to undetected particles of dark matter.

如果它们仍然存在于当前的宇宙中，它们可能构成了我们可以在星系旋转和宇宙结构中推断出的部分或全部缺失质量，而科学家通常将这些质量与未检测到的暗物质粒子联系起来。

“They’re one of the few good theories for what dark matter could be,” Qin said.

“它们是关于暗物质可能是什么的为数不多的好理论之一，”秦说。

“So it’s important to keep looking for them.”

“所以继续寻找它们很重要。”

To the surprise of Kaiser’s team, the idea that the neutrino that crashed into the KM3NET detector originated in the explosion of a primordial black hole worked mathematically, and on September 18, 2025, Kaiser and Klipfel published a paper in Physical Review Letters explaining the mechanism.

令 Kaiser 团队惊讶的是，撞击 KM3NET 探测器的中微子起源于原初黑洞爆炸的想法在数学上是成立的，2025 年 9 月 18 日，Kaiser 和 Klipfel 在《物理评论快报》上发表了一篇论文，解释了这一机制。

They found that, if a primordial black hole with the initial mass of a small asteroid exploded about 2,000 astronomical units away — 2,000 times the distance between the Earth and the sun — it could have produced the powerful neutrino.

他们发现，如果一个初始质量相当于一颗小行星的原始黑洞在大约 2000 个天文单位之外（地球与太阳之间距离的 2000 倍）爆炸，它可能会产生强大的中微子。

“We found about an 8% chance of this happening,” Klipfel said.

“我们发现这种情况发生的可能性约为 8%，”Klipfel 说。

“It’s a low-probability event.

“这是一个低概率事件。

But it’s not a completely impossible event.”

但这并不是一件完全不可能的事情。”

This visualization shows a particle passing through the KM3NET detector and activating a series of optical modules.

该可视化显示了一个粒子穿过 KM3NET 探测器并激活一系列光学模块。

The PBH, at the lower 100-trillion-gram end of the asteroid-mass window, would have steadily emitted Hawking radiation over the 13.8-billion-year lifespan of the universe until its explosive finale.

PBH 位于小行星质量窗口的 100 万亿克下端，在宇宙 138 亿年的寿命中稳定地发射霍金辐射，直到爆炸结束。

Had the PBH been much closer, we likely would have seen its flash in gamma rays or other radiation that would have signaled its final explosion.

如果 PBH 离得更近，我们很可能会看到它在伽马射线或其他辐射中的闪光，这标志着它的最终爆炸。

If it had been too far away, the neutrinos would have been too spread out for one to hit Earth.

如果距离太远，中微子就会太分散，无法撞击地球。

Models in which PBHs account for most or all of the dark matter also predict that enough of the smaller PBHs would have the correct mass for one to fly past our solar system right as it exploded, producing a burst of energetic particles, including the neutrino that hit our planet in just the right spot to trigger the KM3NET detector.

PBH 占暗物质的大部分或全部的模型还预测，足够多的较小的 PBH 具有正确的质量，可以在爆炸时飞过我们的太阳系，产生一阵高能粒子，其中包括中微子，它们恰好撞击我们的星球，触发 KM3NET 探测器。

Carr, who solidified the concept of PBHs with Hawking, finds the idea enticing and is hopeful that KM3NET’s spectacular neutrino is a sign that we might discover PBHs after all.

卡尔与霍金一起巩固了PBH的概念，他发现这个想法很诱人，并希望KM3NET壮观的中微子是我们最终可能发现PBH的标志。

“I’ve been working on primordial black holes for 50 years, and there was no purported evidence for them, just constraints, which is really sad,” Carr said.

卡尔说：“我研究太初黑洞已经有 50 年了，但并没有任何所谓的证据，只有一些限制，这真的很悲伤。”

“This could be evidence for black hole explosions.”

“这可能是黑洞爆炸的证据。”

Not everyone is convinced.

并非所有人都相信。

“I don’t know where this KM3NET neutrino comes from, but I would bet an awful lot of money that it has nothing to do with primordial black holes,” said Dan Hooper, a cosmologist at the University of Wisconsin, Madison.

威斯康星大学麦迪逊分校的宇宙学家丹·胡珀 (Dan Hooper) 表示：“我不知道这个 KM3NET 中微子从何而来，但我敢打赌，它与原始黑洞无关。”

He argues that if such exploding black holes existed, they would be easy to see, “and we don’t see those,” he said.

他认为，如果这种爆炸的黑洞存在，它们很容易被看到，“但我们看不到那些，”他说。

“I think you can completely rule out that hypothesis.”

“我认为你可以完全排除这个假设。”

Hooper is not completely opposed to the idea of PBHs themselves, however, and he has worked to understand how they might have formed during the period of cosmic inflation.

然而，胡珀并不完全反对PBH本身的想法，他一直致力于了解它们在宇宙膨胀时期是如何形成的。

“There are lots of ways they could have been made in the early universe,” he said.

“在早期宇宙中有很多方法可以制造它们，”他说。

Workers prepare to deploy a string of optical sensors, which will be attached to the seafloor and unspooled from the spherical frame that contains them.

工人们准备部署一串光学传感器，这些传感器将连接到海底并从包含它们的球形框架上解开。

Others, like Evan McDonough, a theoretical physicist from the University of Winnipeg, are more confident that PBHs exist today.

其他人，比如温尼伯大学的理论物理学家埃文·麦克唐纳 (Evan McDonough)，则对PBH 今天的存在更有信心。

“My personal hunch is that there is probably at least one PBH out there,” he said.

“我个人的直觉是，那里可能至少存在一个 PBH，”他说。

“Whether or not they exist in some sizable amount is the big question.”

“它们是否大量存在是一个大问题。”

Priyamvada Natarajan , a theoretical astrophysicist from Yale University, says that although she thinks PBHs cannot account for more than a tiny fraction of dark matter, she is interested in them as a tool to explore ideas for dark matter outside its two most popular candidates, weakly interacting massive particles (WIMPs) and the more wavelike axions.

耶鲁大学的理论天体物理学家 Priyamvada Natarajan 表示，尽管她认为 PBH 只能解释暗物质的一小部分，但她对将其作为一种工具来探索暗物质的想法很感兴趣，这两种最流行的候选者是弱相互作用大质量粒子（WIMP）和更具波状的轴子。

“PBHs are really forcing us to rethink the dark matter problem and move away from our fixation with WIMPs and axions,” she said.

“PBH 确实迫使我们重新思考暗物质问题，并摆脱对 WIMP 和轴子的关注，”她说。

“In that sense they’re scientifically really important.

“从这个意义上说，它们在科学上非常重要。

They’ve allowed us to break out of a mindset and be more open.”

他们让我们能够打破思维定势，变得更加开放。”

If primordial black holes exist, there are several ways we might find them.

如果太初黑洞存在，我们可以通过多种方式找到它们。

For example, we might spot a signal in gravitational waves from the merger of PBHs smaller than the mass of a star but still huge enough to produce detectable gravitational waves in our instruments.

例如，我们可能会在比恒星质量还小的PBH合并产生的引力波中发现信号，但其质量仍然足够大，足以在我们的仪器中产生可检测到的引力波。

Black holes of such mass would have needed to form through primordial means.

如此质量的黑洞需要通过原始手段形成。

Andrea Thamm of the University of Massachusetts, Amherst and her colleagues, meanwhile, proposed in September that exploding black holes might be more common than theorists thought and could be spotted in the near future, if we invoke some exotic physics.

与此同时，马萨诸塞大学阿默斯特分校的安德里亚·塔姆 (Andrea Thamm) 和她的同事在 9 月提出，如果我们援引一些奇异的物理学，黑洞爆炸可能比理论学家想象的更常见，并且可能在不久的将来被发现。

In their model, they suggest that particles known as dark photons and dark electrons — dark matter variants of normal matter — could have reduced the rate at which lower-mass PBHs in the universe emitted Hawking radiation.

在他们的模型中，他们认为被称为暗光子和暗电子的粒子（正常物质的暗物质变体）可能降低了宇宙中低质量PBH发出霍金辐射的速率。

That could mean many more PBHs are in the final stages of evaporation today.

这可能意味着今天有更多的 PBH 处于蒸发的最后阶段。

If that’s so, Thamm and colleagues suggest that within certain constraints, there is a more than 90% chance of spotting the evaporation of a primordial black hole in the next 10 years.

如果真是这样，Thamm 和他的同事认为，在一定的限制下，未来 10 年内有超过 90% 的机会发现太初黑洞的蒸发。

A “backbone cable” connects multiple optical modules in the KM3NET detector.

“主干电缆”连接 KM3NET 探测器中的多个光学模块。

“Within a fairly short time window [of the final explosion], around 1,000 seconds, there would be very highly energetic photons [emitted],” said Thamm, who said existing experiments like the High-Altitude Water Cherenkov observatory in Mexico could look for such events.

塔姆说：“在（最终爆炸的）相当短的时间窗口内，大约 1000 秒，将会发射出非常高能的光子。”他说，墨西哥高空水切伦科夫天文台等现有实验可以寻找此类事件。

“And then it would very suddenly stop once the primordial black hole has exploded.”

“一旦原始黑洞爆炸，它就会突然停止。”

Another novel idea, proposed by Kaiser, is that if PBHs do indeed fall into the asteroid-mass range and constitute most or all of dark matter, they should occasionally fly through our solar system at hundreds of kilometers a second.

凯撒提出的另一个新颖的想法是，如果PBH确实落入小行星质量范围并构成大部分或全部暗物质，它们偶尔应该以每秒数百公里的速度飞过我们的太阳系。

In this scenario, they might produce noticeable gravitational effects.

在这种情况下，它们可能会产生明显的引力效应。

Using spacecraft orbiting Mars, Kaiser said, we could precisely calculate the distance from Earth to the red planet and look for any wobbles that might indicate a PBH flying past.

凯泽说，利用绕火星运行的航天器，我们可以精确计算从地球到这颗红色行星的距离，并寻找可能表明 PBH 飞过的任何摆动。

At any given time, he said, there would be at least one PBH in the solar system, possibly producing detectable Hawking radiation .

他说，在任何给定时间，太阳系中都会至少存在一个PBH，可能会产生可检测到的霍金辐射。

Every three to 10 years, one would get close enough to Mars to produce a tiny but measurable change in the planet’s motion.

每三到十年，一颗行星就会距离火星足够近，从而对行星的运动产生微小但可测量的变化。

In the tens of centimeters, “Mars will begin rocking away from its otherwise well-tracked orbit,” Kaiser said.

凯撒说，在几十厘米的距离内，“火星将开始偏离其正常运行的轨道”。

He is planning to work on the idea with a team of astronomers over the next couple of years.

他计划在未来几年与天文学家团队一起研究这个想法。

Alongside that, Kaiser wants to keep an eye out for other high-energy neutrinos to test the idea that some might come from exploding black holes.

除此之外，凯撒还想密切关注其他高能中微子，以测试其中一些中微子可能来自黑洞爆炸的想法。

Proving that this is true is difficult because PBH neutrinos would look just like any other neutrinos produced from another source, unless they could be associated with a flash of gamma rays in the sky from an exploding PBH.

证明这一点是正确的很困难，因为 PBH 中微子看起来就像其他来源产生的任何其他中微子一样，除非它们与天空中爆炸的 PBH 产生的伽马射线闪光有关。

There is still a long way to go before we can say whether primordial black holes exist, let alone whether they make up dark matter.

要说原始黑洞是否存在，还有很长的路要走，更不用说它们是否构成暗物质了。

But for now, scientists cannot rule out the possibility that one slipped past Earth nearly three years ago, sending a lone emissary into an underwater neutrino detector.

但目前，科学家们还不能排除一种可能性，即大约三年前，有一颗中微子溜过地球，将一名孤独的使者送入水下中微子探测器。

“The numbers are outrageously congruent, considering I walked in half-joking,” Kaiser said.

“考虑到我半开玩笑地走进来，这些数字惊人地一致，”凯撒说。

Editor’s note: Priyamvada Natarajan is a member of Quanta Magazine ’s advisory board.

编者注：Priyamvada Natarajan 是 Quanta 杂志顾问委员会成员。

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Quanta Magazine moderates comments to facilitate an informed, substantive, civil conversation.

《Quanta》杂志对评论进行审核，以促进知情、实质性、文明的对话。

Abusive, profane, self-promotional, misleading, incoherent or off-topic comments will be rejected.

辱骂、亵渎、自我推销、误导、语无伦次或偏离主题的评论将被拒绝。

Moderators are staffed during regular business hours (New York time) and can only accept comments written in English.

版主在正常工作时间（纽约时间）有工作人员，并且只能接受英文评论。