 is invisible, mysterious stuff that we call dark matter and dark energy. And we have no idea as particle physicists what these things are. So we're in this really weird position of not knowing what 95% of the universe is made from. So we think that there must be more to these pictures than we've been able to fill in so far. And as a scientist, when you see something that doesn't fit your picture, that's the most exciting thing, because it's usually the thing that doesn't fit