标题： 为什么我们生活在三维空间加一维时间中？ 显示英文标题

标题： Why Do We Live in 3+1 Dimensions?

摘要： 注意到标准模型中的费米子最好被视为 Weyl 粒子（相对于某些假设的非常高的能量所确定的基本尺度），有趣的是，Weyl 方程挑出了实验上的时空维度：观察到恰好在实验上真实的时空维数 4 = 3 + 1 中，Weyl 方程中作为矩阵的线性独立矩阵数量$n_{Weyl}^2$等于维度$d$。 因此，仅在这种维度下（事实上，在平凡情况$d=1$下也是如此），Weyl 方程的 sigma-矩阵形成一组基底。 对于这种维度，另一个特征是 Weyl 自旋子的所有非零动量的螺旋态都没有简并。 我们希望将这些特性解释为 Weyl 方程在现象学上真实的时空维度中具有特殊的“形式稳定性”。 为了使这种稳定性在尽可能大的允许修改范围内出现，我们讨论了是否有可能定义“自然法则的稳定性”可能意味着什么。 显示英文摘要

摘要： Noticing that really the fermions of the Standard Model are best thought of as Weyl - rather than Dirac - particles (relative to fundamental scales located at some presumably very high energies) it becomes interesting that the experimental space-time dimension is singled out by the Weyl equation: It is observed that precisely in the experimentally true space-time dimensionality 4=3+1 the number of linearly independent matrices $n_{Weyl}^2$ dimensionized as the matrices in the Weyl equation equals the dimension $d$. So just in this dimension (in fact, also in a trivial case $d=1$) do the sigma-matrices of the Weyl-equation form a basis. It is also characteristic for this dimension that there is no degeneracy of helicity states of the Weyl spinor for all nonzero momenta. We would like to interpret these features to signal a special ``form stability'' of the Weyl equation in the phenomenologically true dimension of space-time. In an attempt of making this stability to occur in an as large as possible basin of allowed modifications we discuss whether it is possible to define what we could possibly mean by ``stability of Natural laws''.