A recent paper Pal (2022 Eur. J. Phys. 43 015204) puts into covariant form an extension of relativistic classical electromagnetism from free space to a linearly polarizable medium. The paper is based on the assumption that the relativistic tensor, F ^{μ ν} , which is a tensor in free space, will also be a tensor in a linear medium. Pal constructs a proposed covariant formulation that gives Fμν  for a medium moving with constant velocity, v, in terms of F ^{μ ν} for the medium at rest. However, although F ^{μ ν} has been proven to be a relativistic tensor in free space, we show that it is not a tensor in a linear medium. This means that the covariant extension proposed by Pal fails.

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对“各向同性介质中电动力学的协变公式”的评论


最近的一篇论文 Pal (2022 Eur. J. Phys. 43 015204) 将相对论经典电磁学从自由空间到线性极化介质的扩展引入了协变形式。该论文基于这样的假设：相对论张量 F ^{μ ν} 是自由空间中的张量，也将是线性介质中的张量。 Pal 构建了一个建议的协变公式，该公式给出了以恒定速度 v 移动的介质的 Fμν，以静止介质的 F ^{μ ν} 表示。然而，尽管 F ^{μ ν} 已被证明是自由空间中的相对论张量，但我们证明它不是线性介质中的张量。这意味着 Pal 提出的协变扩展失败了。