: This is one of the most cited papers on this topic. Tegmark argues that our 3+1 dimensional spacetime (3 space, 1 time) is "privileged." He demonstrates that:
would lead to unstable atoms and planetary orbits. Spacetime Dimension
Several foundational and modern papers explore the dimensionality of spacetime, ranging from explaining why our universe has 3 spatial and 1 temporal dimension to theoretical frameworks involving multiple time dimensions or "scale-dependent" dimensionality. Landmark Papers on Spacetime Dimensions : This is one of the most cited papers on this topic
might be too simple to support observers. You can read the full text at arXiv:gr-qc/9702052 . Spacetime Dimension