I often see that my dog is staring at something, and he looks very suspicious about it. When I try to look for what he's staring at, almost 95% of the time is just "empty space". I always think he is staring at some rare energies that I can't percieve... actually, sometimes I hear strange noises in my house, and my dog is always alert, staring at something when that happens... sometimes it gets a bit scary, when he appears to be staring at me, but he's clearly not seing me (I know this becouse after a while, he actually sees me, and act like he normally does)

Wtf is filling that space the other 5% of the time?
Say something's moving around outside - the dog may stare at the location of the sound. To us, with our less sensitive ears, there's no sound... or it's minor. But to the dog it's a clear sound. Clear enough they can locate where it is through the wall.
Which is why they appear to be staring at "nothing".