We live in a world of macro matter. Our intuition, experience, is built upon objects which we can manipulate, distances we can travel and observations we can do with our eyes. However, our brain has been programmed to assume and that's why magic work. For example, see how a magician survive head chopper.
But in reality, the universe is large, very large indeed. The stuff that make up matter is small, very small. These are beyond our daily experience and hence beyond our intuition. How and what can we do to understand such scenarios where our intuition no longer help?
The telescope allows us to see far, so far that we are looking back at time. The microscope enables us to see small. We also learn to extend our vision by detecting light which we cannot see, into the infra-red, ultra-violet. To really understand the inner working of matter, large machine are built to smash together matter - to split them apart and try to see what comes out.
Physicists have been making out senses of the universe - that's Einstein's Theory of Relativity. By formulating a mathematical model of space-time, Einstein described the large dimensions. Anyone can propose a theory. The most important part of any science is evidence. Experiments which allow us to determine if a theory is correct or not. For example, Theory of relativity predicts that a fast moving clock will appear slower to a slower moving reference frame. It also predicts that light will bend by the gravitational pull of massive bodies. Such strange ideas are not intuitive because our experience and interaction with reality do not occur at that level and size. The change of time due to relative motion is too small to be detected by direct human senses. But both of these strange observations have been made and proven to be exactly the same as predicted by the theory of relativity.
On the other side is the very small - the domain of quantum mechanics. It turns out that we can apply the same technique. Formulate a theory and then test if the theory can predict something which we can put to a test. Again, strange ideas such as uncertainty principle, teleportation have been tested and quantum theory passed with flying colours.
Stephen Hawking and Leonard Miodinow's latest book explains the origin of the universe without any difficult maths. I highly recommend reading it.