Is it possible for dark matter to create the regular matter that we, the stars, and the galaxies are made of? The reason I'm asking this is because I have a hard time imagining how something can basically just come out of nothing (The Big Bang). So I was thinking, what if there was dark matter "before" big bang. Is it possible for dark matter to have existed before The Big Bang? Did dark matter actually come into place because of The Big Bang?
Is it possible for dark matter to create the regular matter that we, the stars, and the galaxies are made of?
One has to define "create". In the standard model of particle physics which we ( physicists of some experience) believe describes the overwhelming majority of the data, "create" means interactions between particles with energy transforming according to strict quantum mechanical rules into other particles and different manifestations of energy.
Dark matter was found and defined as "dark" because it was necessary in order to explain the motions of galaxies and clusters of galaxies according to the laws of gravity ( gravity is the fourth interaction not yet unified in a standard model). It was called "dark" because it was not interacting with the three known forces ( strong, weak electromagnetic) of the standard model: no energy or particles were coming from this mass so it is not detectable in any other way than in gravitational anomalies.
So no, within our measurement errors dark matter cannot create ordinary matter, although if one finds a quantum theory of gravity it is expected that at very low probabilities there will be some creation of ordinary matter, though below our detection capabilities and certainly not creating the visible matter of the standard model.
The reason I'm asking this is because I have a hard time imagining how something can basically just come out of nothing (The Big Bang).
Nobody has to imagine this. One has just to imagine that there was a discontinuity in space time called the Big Bang which started our space time. That is as far as we go and can check experimentally.
Example: suppose you are a primitive man and you see projectiles falling on your land. The fact is that projectiles fell.The reason can be very variable : volcano, bomb,meteorites.. but the primitive man cannot imagine these sources, before the fact of the seen projectiles. We are like the primitive men as far as the Big Bang goes. We see by measurements that there was a dispersion of space-time/ energy-momentum from a discontinuity but the before is a matter of fitting various models etc, not of hand waving.
So I was thinking, what if there was dark matter "before" big bang.
It is a hypothesis that might become viable if entered into a specific mathematical model, but probably not. One expects symmetries to exist in any model of the cosmos and just dark matter is an asymmetric proposition. Anyway as you were told in the comments the road to understanding such models and reaching the point of creating your own is long and goes through graduate school + .
Is it possible for dark matter to have existed before The Big Bang?
Did dark energy actually come into place because of The Big Bang?
That is the prevalent theory, that dark energy is necessary to explain the observed evolution of the expansion of the Universe down to our own times. Seems to fit well. More observations might change this, but again I doubt it.