A discussion of the advantages and limitations of the concept of critical balance, as employed in turbulence phenomenologies, is presented. The incompressible magnetohydrodynamic (MHD) case is a particular focus. The discussion emphasizes the status of the original Goldreich & Sridhar (1995) critical balance conjecture relative to related theoretical issues and models in an MHD description of plasma turbulence. Issues examined include variance and spectral anisotropy, influence of a mean magnetic field, local and nonlocal effects, and the potential for effects of external driving. Related models such as Reduced MHD provide a valuable context in the considerations. Some new results concerning spectral features and timescales are presented in the course of the discussion. Also mentioned briefly are some adaptations and variations of critical balance.

中文翻译：

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临界平衡与磁流体动力学湍流物理学

讨论了湍流现象学中使用的临界平衡概念的优点和局限性。不可压缩的磁流体动力学 (MHD) 案例是一个特别的焦点。讨论强调了原始 Goldreich & Sridhar (1995) 临界平衡猜想相对于 MHD 等离子体湍流描述中的相关理论问题和模型的地位。检查的问题包括方差和光谱各向异性、平均磁场的影响、局部和非局部效应以及外部驱动的潜在影响。相关模型（如Reduced MHD）提供了一个有价值的考虑因素。在讨论过程中提出了一些关于光谱特征和时间尺度的新结果。