# Tag Info

### Compactification in String Theory and Compactification in Topology are they the same thing?

I don't know much about compactification in string theory, but the idea is based on the compactification in (4+1) D Kaluza-Klein theory, proposed in the years after the theory of general realtivity ...
• 1,344

### Compactification in String Theory and Compactification in Topology are they the same thing?

No, different concepts. The compactification in string theory is the process of taking a theory with extra infinitely extended dimensions (w.r.t. the canonical 3+1 dimensions) and modifying it so that ...
• 4,390

### Assuming FLRW is correct, can it be 3-torus?

The assumption underlying the FLRW metric is that space is homogeneous and locally isotropic. Schur’s Theorem states that a connected Riemann manifold of dimension $n>2$ that is locally isotropic ...
• 99
No, it is not. We compactify $\mathbb{R}$ to become a $\mathbb{S}^1$ by gluing $x\sim x+2\pi$, which is an universal covering $j:\mathbb{R}\rightarrow \mathbb{S}^1$.