Dark matter is inferred from affect, in the light of existing theory. However, it has never been proven in the lab, using direct observation. This is the same proof schema that is used for God. We have never seen God in the lab. God is inferred by the faithful, by affect; beauty and complexity of nature as well as by the mystery of the creation of our universe from nothing.
Physics assumes there is no preferred reference and therefore there is no center of the universe. The problem with this is, this violates the conservation of energy since relative reference allows for different energy perceptions, based on the reference used. The odds are we are not using the proper reference for observation and thereby end up observing things that suggest that there is more energy on the universe, than the theory assumes. The result is an addendum called dark energy and matter.
The analogy is say we lived on a plateau with a large lake in the middle. Since we never go to the edge, we define the lake as sea level, since all the rain water flows down hill and ends in the lake. One day we notice the lake is lowering and should be rising.
We ask ourselves, how is this possible, since the lake is already at lowest potential? The explanation is the lake has gravitational potential, since it exists on the plateau. Everything on there plateau has potential with the valley below. But since we never go to the edge to see the valley, we postulate that there must be a new form of mystery energy than can account for the observations we see. We will never see this mystery energy in the lab since it is a reference illusion. It is not anything new; it is only gravity.