近三年前，一枚来自太空的中微子撞击地中海，在西西里岛外海尚未完全建成的立方千米中微子望远镜（KM3NET）中触发了信号。该粒子的能量约为此前观测到的任何中微子的35倍，显著高于南极IceCube观测站十余年来记录的数百个宇宙中微子。其来源可能是高度活跃的耀变体星系，或被认为弥漫于宇宙中的高能宇宙学背景粒子，但目前尚无定论。

在缺乏明确解释的情况下，一种更激进的假设被提出：该中微子可能来自一个正在爆发的原初黑洞。原初黑洞被认为形成于宇宙诞生后的最初瞬间，甚至早于原子和恒星的出现。如果它们存在，可能在暗物质组成中扮演角色。尽管提出这一想法的物理学家承认这是一种小概率猜测，但如此极端能量的单一事件，使得这一可能性尚未被排除。

原初黑洞的理论起源可追溯至1966年，由苏联物理学家泽尔多维奇和诺维科夫首次提出，并在1971年由史蒂芬·霍金进一步发展，随后于1974年与伯纳德·卡尔系统化。理论认为，在宇宙最初极短时间内，时空密度的剧烈起伏可能导致塌缩形成黑洞，其质量跨度巨大，最小者甚至可与原子核相当。这一框架为解释极端高能中微子事件提供了一个虽不确定但引人注目的物理背景。

Nearly three years ago, a neutrino from space struck the Mediterranean Sea and lit up the partially completed Cubic Kilometer Neutrino Telescope (KM3NET) off the coast of Sicily. Its energy was about 35 times higher than any neutrino previously observed, far exceeding the hundreds of cosmic neutrinos detected over more than a decade by Antarctica’s IceCube observatory. Possible sources include a highly active blazar or a diffuse background of ultra-high-energy cosmogenic particles, but no definitive explanation has emerged.

In the absence of certainty, a more radical idea has been floated: the particle may have come from an exploding primordial black hole. Such black holes are thought to have formed in the earliest moments of the universe, before atoms or stars existed, and could potentially contribute to dark matter. Although the proposal is acknowledged as a long shot, the extraordinary energy of the event keeps the hypothesis in play.

The concept of primordial black holes dates back to 1966, when Yakov Zel’dovich and Igor Novikov first proposed it, and was expanded by Stephen Hawking in 1971 and further formalized with Bernard Carr in 1974. The theory suggests that extreme density fluctuations in the universe’s first split second could have collapsed into black holes spanning a vast mass range, with the smallest potentially as tiny as an atomic nucleus. This framework provides a speculative but compelling context for interpreting the unprecedented neutrino detection.