To be more accurate it is if you find an explanation with more accurate predictive capability, after observing something the current theory does not predict. You can't, so it stands.
The current theory has made it so we have to believe in dark matter and dark energy, things we can't observe, because then the equations work out. Prediction didn't match observation.
Except their effects have been observed. Observing those effects has actually helped confirm general relativity as dark matter has been seen warping space.
"Observing the effects" is just a clever way of saying "it must be there, otherwise our equations are way off". They might as well call it The Force that holds the universe together.
That is incorrect. We have observed dark matter separate from regular matter. When galaxies collide the dark matter continues past, and causing gravitational lensing without matter.
Show me. Sounds easily p-hackable(like the original dog feces data they took with the sun bending starlight etc.)
An article about it. This is observed in many galaxy and galaxy cluster collisions.
