Scientists have assigned the role of Mister Answer to science, the source of knowledge on every subject. This is peculiar because science does not accept a complete body of knowledge at any one time as final, therefore no answer can be final. This is how science progresses. Scientists, though, often forget that.
Much of modern physics has been about exploring inherently invisible things, which seem to be far more common than the obvious things we experience with our senses. Yet these invisible things follow rigorous laws that allow us to test their existence in many ways. Here is a very short list of some of the "invisible" things that we routinely work with.