Gravity and magnetism. Yet our 'science' is built around their behavior.
I’m perfectly willing to consider the possibility of dark matter, and the even more weird dark energy.
I think that planets with no 'star' would be 'dark', and that explains the 'missing' matter.
Dark energy? I would suggest that 'dark energy' was just a theory used to explain why the galaxy mass/gravitational pull calculations didn't work out. As it turns out, they are seeing that there is just a lot more 'mass' lying around than they had ever imagined, or could see.
But to assume as a fact the existence of something we cannot see in order to make what we can see fit the theories is not a very scientific approach.
Well... it's worked for thousands of years (or billions, who knows).
Same is true for dark matter, I suspect.
As it turns out, they are seeing that there is just a lot more 'mass' lying around than they had ever imagined, or could see.
Well, no, we aren't "seeing" this matter. We are projecting its existence to explain anomalies between our observations and our theories.
Saying that we are "seeing" this matter is similar to claiming that anthropogenic global warming is out of control because that's what the computers project.
Theories are not facts, they're just theories. Dark matter/energy and AGW may turn out to be facts, but at the moment they're just theories.
I should also point out that we have yet to observe the existence of a single dark planet, yet these guys are proposing their total mass exceeds that of the stars in our galaxy. That’s a remarkable jump.
It’s saying not only that unicorns exist, but that they outnumber people.