A photon from the biggest cosmic explosion since the Big Bang appears to have defied Einstein. Scientists may finally know how

自大爆炸以来最大的宇宙爆炸中的一个光子似乎违抗了爱因斯坦。科学家们可能最终知道如何

A photon, or particle of light, from the biggest cosmic explosion since the Big Bang, nicknamed "the BOAT" (for the brightest of all time), should not have reached Earth. That is, unless it defied rules defined by Einstein. Now scientists may know how it did this, with new research suggesting how the high-energy photon may have survived a journey of more than two billion light-years without being absorbed.

一个光子，也就是光的粒子，来自自宇宙大爆炸以来最大的宇宙爆炸，绰号为“BOAT”（意为“史上最亮”），原本不应该到达地球。也就是说，除非它违背了爱因斯坦所定义的规则。如今，科学家们或许知道了它是如何做到这一点的：一项新研究提出了这个高能光子如何可能在超过20亿光年的旅程中未被吸收而幸存下来。

The BOAT, a gamma-ray burst officially designated GRB 221009A, was first detected on Oct. 9, 2022. Among the ocean of photons from the event that rained down on our planet was the highest-energy photon ever detected originating from a gamma-ray burst. It was detected by Carpet, an ultra-high-energy cosmic-ray detector located at the Baksan Observatory in the Russian Caucasus.

“BOAT”是一个伽马射线暴，正式编号为GRB 221009A，于2022年10月9日首次被探测到。在该事件如雨点般倾泻到我们星球上的海量光子中，有一个是迄今探测到的、源自伽马射线暴的能量最高的光子。它是由Carpet探测到的，而Carpet是位于俄罗斯高加索地区巴克桑天文台的一个超高能宇宙射线探测器。

The problem is, according to all current rules of physics, a particle with such high energy shouldn't reach Earth from an explosion occurring such a vast distance away. That's because space isn't empty; it is filled with a "fossil" radiation field of photons left over from just after the Big Bang called the cosmic microwave background (CMB). It should be virtually impossible for a high-energy photon to travel 2 billion light-years without interacting with a CMB photon and being transformed. And still it came.

问题在于，按照目前所有物理学规律，如此高能量的粒子本不应从如此遥远距离外发生的爆炸抵达地球。这是因为太空并非空无一物；它充满了大爆炸后不久遗留下来的光子“化石”辐射场，称为宇宙微波背景（CMB）。一个高能光子要穿行20亿光年，却不与一个CMB光子相互作用并发生转变，按理说几乎是不可能的。然而，它还是来了。

"We started from a very simple question: how did this photon survive a journey that, according to known physics, should have destroyed it?" team leader Giorgio Galanti from the Italian National Institute for Astrophysics (INAF) said in a statement. "The new data from the Carpet experiment showed us that the explanations proposed so far were no longer sufficient.

“我们从一个非常简单的问题出发：按照已知物理学，这个光子本应在旅途中被摧毁，那它究竟是如何幸存下来的？”意大利国家天体物理研究所（INAF）的团队负责人乔治·加兰蒂在一份声明中说。“Carpet实验的新数据向我们表明，迄今为止提出的解释已不再充分。”

"We therefore looked for a theoretical scenario capable of consistently describing what we observe, without resorting to arbitrary corrections to the equations."

“因此，我们寻找了一种理论方案，能够自洽地描述我们所观测到的现象，而无需对方程进行任意修正。”

To investigate the mystery of how this high-energy photon reached our planet, Galanti and colleagues turned to incredibly light hypothetical particles called axion-like particles (ALPs).

为了探究这个高能光子是如何到达我们星球的这一谜团，加兰蒂及其同事转向了被称为类轴子粒子（ALPs）的极其轻的假想粒子。

ALPS could serve as a solution to this puzzle via a mechanism that would allow photons to transform into ALPs as they travel and then convert back into photons as they reach the Milky Way. The problem is that this still can't account for such a high-energy photon.

类轴子粒子（ALPs）可以通过一种机制来解开这个谜题：这种机制允许光子在传播过程中转变为ALPs，然后在抵达银河系时再转变回光子。问题在于，这仍然无法解释这样一个高能光子。

This team combined the idea of ALPs with a proposed violation of one of the fundamentals of Einstein's 1905 theory of special relativity called "Lorentz invariance."

该团队将ALPs这一设想与另一种假设结合起来，即爱因斯坦1905年狭义相对论的一条基本原理——“洛伦兹不变性”——可能遭到破坏。

In short, Lorentz invariance says that observers moving at different speeds should experience the same physical laws. The team tested the idea that Lorentz invariance could be violated at high energies, thus changing how photons propagate through space.

简而言之，洛伦兹不变性认为，以不同速度运动的观察者应体验到相同的物理定律。该团队检验了这样一种设想：洛伦兹不变性可能在高能下被破坏，从而改变光子在空间中传播的方式。

In the scenario devised by the team the photon would have avoided being wiped out by interactions with the CMB as it would avoid interactionc with these fossil photons.

在该团队设想的场景中，这个光子会避免因与宇宙微波背景（CMB）发生相互作用而被摧毁，因为它会避开与这些“化石”光子的相互作用。

The new research therefore implies that at high enough energies, photons can take a "fast lane" through a transparent universe, dodging the physics that would normally force their destructive transformation.

因此，新的研究意味着，在足够高的能量下，光子可以在透明宇宙中“快车道”，避开通常会迫使它们发生破坏性转变的物理学。

Interestingly, there is some evidence relating to the BOAT that seemingly backs this theory. According to the picture developed by the team, this high-energy photon should have arrived at Earth around one hour after lower-energy particles of light originating from the BOAT. Indeed, that is exactly what happened.

有趣的是，有一些与“BOAT”相关的证据似乎支持这一理论。根据该团队构建的图景，这个高能光子本应比源自“BOAT”的低能光子晚大约一小时抵达地球。事实正是如此。

"The most interesting aspect of our work is that, for the first time, it brings together two ideas that until now had been developed separately," team member Marco Roncadelli of the National Institute for Nuclear Physics (INFN) said. "If future observations confirmed this scenario, the universe would become a natural laboratory for studying quantum gravity at energies enormously higher than those achievable by any accelerator built on Earth."

“我们这项工作最引人注目的地方在于，它首次将两个此前各自独立发展的想法结合在一起，”意大利国家核物理研究所（INFN）团队成员马尔科·龙卡代利说。“如果未来的观测证实这一设想，宇宙将成为研究量子引力的天然实验室，其能量尺度将远远超过地球上任何加速器所能达到的水平。”

The team's research is available on the repository site arXiv and has been accepted for publication in the journal Physical Review Letters.

该团队的研究可以在存储库网站arXiv上找到，并已被《《物理评论快报》》杂志接受发表。