“There is a fifth dimension, beyond that which is known to man. It is a dimension as vast as space and as timeless as infinity. It is the middle ground between light and shadow, between science and superstition.” -Rod Serling
If we take a look at a two-dimensional surface, it’s pretty apparent that we’re pretty omnipotent in comparison. We can draw or erase anything in that dimension, add or remove objects, rearrange their internal structures without leaving them any defense, etc. All of that might lead you to wonder whether there’s the possibility of a fourth spatial dimension out there, and whether that could be part of our Universe?
Geometrically, it’s certainly possible. From a historical perspective, there’s no reason a dimension needs to stay the same size over time, either. In 1980, Alan Chodos and Steve Detweiler showed that a Universe that began with four spatial dimensions could have easily evolved into a Universe very much like the one we see today. Building on that, it would be possible for a very small extra dimension to grow large over time. If it did, the consequences would be devastating, but fascinating.