THE MOND LIMIT FROM SPACETIME SCALE INVARIANCE
THE MOND LIMIT FROM SPACETIME SCALE INVARIANCE
复制标题
时空尺度不变性的蒙德极限
DOI：
10.1088/0004-637x/698/2/1630
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Milgrom
中科院分区：
文献类型：
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作者：
M. Milgrom
修正牛顿动力学（MOND）极限是根据非相对论性纯引力系统的运动方程的时空尺度不变性要求，即在极限a0→∞时，运动方程在（t, r）→（λt, λr）下的不变性。有人建议这应该取代基于牛顿-蒙德插值函数的低加速度行为的蒙德极限的定义。这样，显著的、深层的mond结果——渐近平坦的旋转曲线、质量-旋转-速度关系（重子Tully-Fisher关系）、Faber-Jackson关系等——都遵循对称原理。例如，旋转曲线的渐近平坦性反映了半径在缩放下发生变化，而速度不变。然后，我评论了将深mond极限解释为“零质量”的解释：静止质量的存在阻碍了尺度对称，与“幻影”、动态质量（有些人将其归因于暗物质）相比，静止质量变得微不足道。与前一种质量不同，后一种质量以一种与对称一致的方式变换。最后，我讨论假定的mond -宇宙学的联系，根据另一个，以前已知的深mond极限的对称性。特别是，有人提出MOND与我们宇宙的渐近德西特几何有关。例如，据推测，在一个精确的德西特宇宙中，深mond物理学将完全适用于局部系统。我还指出，在这方面，德西特-共形场理论（dS/CFT）对偶的可能相关性。
The modified Newtonian dynamics (MOND) limit is shown to follow from a requirement of spacetime scale invariance of the equations of motion for nonrelativistic, purely gravitational systems, i.e., invariance of the equations of motion under (t, r) → (λt, λr) in the limit a0 → ∞. It is suggested that this should replace the definition of the MOND limit based on the low-acceleration behavior of a Newtonian-MOND interpolating function. In this way, the salient, deep-MOND results—asymptotically flat rotation curves, the mass–rotational-speed relation (baryonic Tully–Fisher relation), the Faber–Jackson relation, etc.,—follow from a symmetry principle. For example, asymptotic flatness of rotation curves reflects the fact that radii change under scaling, while velocities do not. I then comment on the interpretation of the deep-MOND limit as one of “zero mass”: rest masses, whose presence obstructs scaling symmetry, become negligible compared to the “phantom,” dynamical masses—those that some would attribute to dark matter. Unlike the former masses, the latter transform in a way that is consistent with the symmetry. Finally, I discuss the putative MOND–cosmology connection in light of another, previously known symmetry of the deep-MOND limit. In particular, it is suggested that MOND is related to the asymptotic de Sitter geometry of our universe. It is conjectured, for example that in an exact de Sitter cosmos, deep-MOND physics would exactly apply to local systems. I also point out, in this connection, the possible relevance of a de Sitter–conformal-field-theory (dS/CFT) duality.