By introducing a new coordinate condition we divide the cylindrical spacetime of Levi-Civita (LC) into a sourceful inner ($\rho \le {\rho }_0=\mathrm{\text{const.}}$) and vacuum outer ($\rho \ge {\rho }_0$) regions. The emergent fluid with zero radial pressure confined to the finely-tuned inner region serves to make the spacetime regular in a natural way. At $\rho =0$ the LC spacetime becomes ‘Cartesian flat’ so that no deficit angle arises.

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关于 Levi-Civita 指标的注意事项

通过引入一个新的坐标条件，我们将 Levi-Civita (LC) 的圆柱时空划分为一个源内 ($\rho \le {\rho }_0=\mathrm{\text{常量。}}$) 和真空外 ($\rho \ge {\rho }_0$) 地区。径向压力为零的涌出流体被限制在微调的内部区域，以自然的方式使时空变得规则。在$\rho =0$LC 时空变为“笛卡尔平面”，因此不会出现赤字角。