5th Dimension and Quantum Physics

Why is the third dimension our self-evident reality, although our sense perceptions are only 2-dimensional? Can a 2-dimensional being hide from a 3-dimensional being? Here are some considerations about the 2nd and 3rd dimension, so we can make an idea for higher dimensions.

The 4th or 5th dimension is not just a mathematical thought experiment, but according to Einstein explains things in our 3-D world, e.g. the power of gravity. How can we imagine a 4th or 5th dimension? Is it only a mathematical-physical construct or is it reality, and are there perhaps even living beings?

Quantum physics and nuclear physics turn our world image upside down. Numerous phenomena seem so puzzling and unreal that science is still struggling to reconcile this with our everyday perception of our world and our reality.