[dark_lord]

The thing is, there are some who would consider this stuff to not be science at all. Think about it. Basically, we have some radio telescopes which produce data, which are massaged fifteen ways from Sunday through various mathematical formula. Then various hypotheses are derived. 6 months or a year later, a new hypothesis du jour is generated. Its all great but all very speculative. No one gets too excited as the theories change, but really, it is similar to running computer models on data from ice cores, possible past volcanic explosions, estimates on solar cycles based on written records that go back to ancient china, and current guess on automobile, factory, and bovine emissions plus the amount of forest growth -- and coming out with another hypothesis on global warming (or cooling).

[longshadow]

The thing is, there are some who would consider this stuff to not be science at all.

And they would be wrong.

As long as the theory behind this is capable of falsification, it meets the test of being "scientific." Every time we gather, and confirm, more evidence about the Universe, the set of viable theoretical explanations gets winnowed as the models that DON'T fit the data have to be modified or dropped, leaving us with a smaller list of theories that DO fit the data.

Over time, the surviving theories approach reality to a greater and greater degree. That's how real science works.

[Physicist]

Basically, we have some radio telescopes which produce data, which are massaged fifteen ways from Sunday through various mathematical formula.

Massage this. Those curvy things are the distorted shapes of very distant galaxies, whose images are being bent by the gravity of the intervening galaxy cluster. It is straightforward to calculate the mass of the cluster from the curvature of the distorted images. It's also straightforward to measure the mass of the normal matter in the cluster, by measuring its spectrum. The difference is the dark matter. It dominates.

Sometimes, new physics has to be sifted painstakingly from the white noise. Other times, it kicks you hard in the testicles. The effort it takes to ignore it is up to you.