In this article it is reported that the nucleus of the typical atom is under great pressure. Greater than that of a neutron star. We also learn that the hadrons in a nucleus are also smaller than they are "free range". That is, outside a nucleus. We also learn that at times hadrons in a nucleus will "overlap", two of them occupying the same space at the same time.
Thing is, physical objects don't exist. Not as we think of physical objects. What you're seeing is a mirage, an illusion. Something we perceive because of how we can perceive and how we are equipped to handle the data we receive. Get right down to it, those two overlapping hadrons aren't really overlapping, it's their constituent parts that are occupying the same space because the vast majority of a hadron is empty space. Other hadrons are ordinarily excluded thanks to something that excludes them, it only when the pressure from the outside overcomes the exclusionary pressure that the two "merge".
There is more I can say about this, but that needs to be composed. Just keep in mind that everything is empty space, it's just that this empty space comes in something like two different flavors and those flavors do interact.