quote:
Are you saying an unseen body does not exist even if the wobble orbit of a nearby says it does ?
Are you going to suddenly cripple this debate by some unflexible definition of the word "know" ?
You are wandering into a purely hypothetical field of science. At best, scientists theorize that dark matter and dark energies exist, nothing more. They don't know what these things are, they don't know how much of them there are, and they don't really know if these are the only things that cause the strange behaviors of the galaxies.
What I am trying to get at is the word "know" is used much more strictly in the fields of science than you think.