Feel all depends how one looks at things. For example, the vacuum, supposedly there should be nothing there. However, uncertainty principle allows fluctuations

Feel all depends how one looks at things. For example, the vacuum, supposedly there should be nothing there. However, uncertainty principle allows fluctuations of all kinds which are not physically directly observable. If one looks at things at the level of principle, it is simple. However, if one tries to look into the actual fluctuations, there is infinite and unknown amount of complexity.