Cosmology, or really cosmogony, tries to answer one of the most fundamental questions of all: Where did the Universe come from? Cosmologists have no idea about the contents of this vast Universe. They speak of many unknowns—dark entities—used to make the standard ΛCDM (Lambda cold dark matter) big bang model fit the observational data. Dark energy and dark matter, which together allegedly make up 95% of the mass/energy content of the Universe, are total unknowns to experimental physics.
But these entities seem more like fudge factors to me than real science. Well, there is good reason for that feeling. They are fudge factors and now it seems like I am not the only one saying it.
In the following I excerpt (indented blue text) from an article titled “Cosmology is in crisis – but not for the reason you may think.” (link for full text) My emphases are in bold text.
We still have no idea what the vast majority of the universe is made of. We struggle to understand how the Big Bang could suddenly arise from nothing or where the energy for “inflation”, a very short period of rapid growth in the early universe, came from. But despite these gaps in knowledge, it is actually human nature – our tendency to interpret data to fit our beliefs – that is the biggest threat to modern cosmology.