科学家发现原初磁场可能解释宇宙膨胀速率之谜

科学家通过详细的三维模拟研究发现，大爆炸后不久产生的微弱原初磁场可能有助于解释长期困扰宇宙学家的"哈勃张力"问题1。这一发现为理解宇宙早期物理过程提供了新的视角。研究人员指出，这些原初磁场可能改变了早期宇宙中氢的形成过程，进而影响到宇宙微波背景观测及由此推断的宇宙膨胀率1。

当前，科学家采用两种不同方法测量宇宙膨胀速率，结果存在显著差异1。基于宇宙微波背景的间接测量方法得出的膨胀率约为67 km/s/Mpc，而基于超新星的直接测量方法给出的数值约为73 km/s/Mpc1。研究团队在模拟中使用的原初磁场强度约为5至10皮高斯1，数据显示支持这一假设的证据达到1.5至3个标准差1。这项研究采用了首个包含嵌入磁场的原初等离子体的完整三维模拟方法1，相关论文已发表在《自然天文学》2025年第10卷第2期1。

Researchers have identified a surprising explanation for a long-standing cosmic puzzle: weak magnetic fields generated shortly after the Big Bang may account for the discrepancy in measurements of how fast the universe is expanding.1 Two distinct methods for measuring cosmic expansion rates have produced conflicting results, with indirect measurements based on the cosmic microwave background yielding approximately 67 km/s/Megaparsec, while direct observations using supernovae suggest approximately 73 km/s/Megaparsec.1

Using the first complete three-dimensional simulations incorporating embedded magnetic fields within primordial plasma, scientists found that these ancient magnetic fields could have altered hydrogen formation in the early universe, subsequently affecting the cosmic microwave background and the expansion rates inferred from it.1 The primordial magnetic fields examined in the research had strengths ranging from 5 to 10 pico-Gauss.1 Evidence supporting the existence of these primordial magnetic fields reached a statistical significance of 1.5 to 3 standard deviations, suggesting the hypothesis remains viable.1 The findings, published in Nature Astronomy in 2025, Volume 10, Issue 2 (DOI: 10.1038/s41550-025-02737-x), provide new insights into the physics of the early universe and offer a novel window for understanding this persistent cosmic discrepancy.1