Picture if you will the walls in the in your room and notice where the two lines intersect in any corner. In relative time you can observe a single point and move towards it and away from it because you physicality exerts a gravitational field. I am suggesting that if you could observe the same two planes (but that would not be possible) with out exerting a gravitational field and observe it. The two planes would never cross, I believe that's why we cant detect dark matter . We look for it in a four dimensional world but dark matter is trapped in a single dimensional state I believe the reason for that is because it lacks enough gravity to enter in to relative space time . It does have an effect on the fabric of space time but it is not detectable in the methods we are looking for it but I do believe its there