I enjoyed the topic.
I would like to add something in support of indeterminism and thus free will, because as others rightfully point out, determinism sure does appear to be prolific in the universe and probably can account for most of the mechanics we see (certainly at the macroscopic level). General relativity is close to explaining this overall. And, in any event I would accept that overall indeterminacy emerges form a sum of parts which are both deterministic and indeterministic, which I will discuss below.
Although it does appear that the conditions to allow our existence came to be from an unimaginably energetic event a very long time ago (as we perceive time, there is disagreement even about how this unfolded, but agreement around how matter came to be at all, and hence
time itself in any meaningful way). Was there only one big bang? Are they cyclical? We don't really know.
Indeterminism is not intuitive and we have a tendency to reject such things as not satisfying our classical understanding of the laws of nature.
An indeterminant process is a stochastic or random process whereby there is some indeterminacy in its future evolution described by probability distributions. This means that
even if the initial condition (or starting point) is known, there are
many possibilities the process might go to, but some paths may be more probable and others less so. The basic idea is that if you have were to be
able to recreate the precise conditions of an experiment right down the last detail, you could still not repeat the results. Some level of randomness would intervene during the manifestation of the outcome to make it unique.
The first thing to acknowledge is that whether the universe is fundamentally deterministic or indeterministic, there are profound implications which can make our heads spin, most notable being for determinism that we would have no genuine free will. And for indeterminism, that paradoxes around the universe being unrealistically disorderly and in defiance of the basic principle of cause and effect, depending on how far you take it.
I do maintain that the universe would still heavily consist of deterministic processes in either case at the macro level and maybe in many processes at the quantum level too, but be overall indeterministic in that the indeterminism pollutes (if you will) the overall evolution of the system to make it stochastic. i.e. a system which is part stochastic must be stochastic overall, at least in this universe as we understand it).
Think of that as 'If I place one dodgy indeterministic domino in a long line of dominoes that behave deterministically, then the overall manifestation of knocking these dominoes is indeterminant.'
It's probably best to focus on the leading argument for indeterminacy in the first place, and that is
radioactive decay.
Above, simulation of many identical atoms undergoing radioactive decay, starting with either 4 atoms (left) or 400 (right). The number at the top indicates how many half-lives have elapsed.
This process is the best
candidate we have in our observed universe as indeterministic phenomena.
The basic reasoning for radioactive decay being genuinely indeterministic is that the process (as they see it) is
not complex enough to create such a complex variance in decay times from atom to atom, for any underlying working to be taking place they don't know about. They rule this out. The generally accepted interpretation is that it decays through a stochastic process, in an indeterministic way. It's not proof. It's evidence.
From an indeterministic viewpoint, it can still be argued that this process still inevitably emerges from the very origin of the universe in an unbreakable chain of deterministic events and that each atom's decay is inevitable. But if so, why do these radioactive atoms bleed off their energy in such an unstable way?
I think this may actually be an indeterministic process. For reasons we don't yet understand, I believe it may be the case that the
superset of our universe (that which determines the workings of our universe), if there is one, determines this. It cannot be proven that chance is at work in this decay, but I believe that if chance is involved, it may come from something deeper, something that existed before the big bang as it were.
To suggest that this process may be manifested from outside of our known universe is no more extreme a view than the universal wave function being outside our known universe determining each parallel universe as in the Many Worlds interpretation that a lot of Determinism proponents are so fond of.
I'm not convinced this is the one and only big bang we have had in this universe or that there isn't something outside of our universe, containing it.