There is a strong "wish it were so" inclination in us humans for the universe to be simple and understandable. This is the motivation for wanting the universe to be predictable and deterministic. It is always a good idea to fight a fallacy that one knows one is tempted by, and be VERY suspicious of views that satisfy one's "wish it were so"s.
Physics at its basic level is indeterministic. QM is probabilistic, and events are random within probability envelopes.
when one builds up to macro scales, then the properties of the structure one is building up, matters.
For most structures, there is a "law of large numbers" that begins to superimpose on the QM indeterminacy. A large number of random events, can be treated as a probabilistic distribution, and when the individual events have a trivial magnitude at the macro scale, they can be approximated as a force rather than events. Pressure for gases, and gravity, are the best known of these "force" approximations to multitudes of quantum events. These force approximations can usually be treated as deterministic at the macro scale.
However, some macro scale structures don't interact as simply as pressure or gravity seem to, and some of those structures have the property of being chaotic. what part of the rim of a faucet a drop falls from, or where and how big a new tropical storm will be -- are classical examples of chaos phenomena. Chaos events are highly sensitive to tiny changes in initial condition, so it is reasonable to expect quantum events to leverage up to macro scales when a system demonstrates chaos behavior.
LIFE has this characteristic of chaos sensitivity. Tiny input changes at the quantum level, have macro scale consequences. Such as -- a cosmic ray produced by QM processes 3 billion years ago in another galaxy, could strike one of my chromosomes, inducing a cancerous change, with drastic consequences for my life.
Our lives are therefore not predictable. But the future of our universe, MAY be predictable, but we think it probably isn't. IF the values of the Standard Model of QM are stable, and never change, then gravity will dominate over the future of the universe, and that is simple enough to be deterministically predictable. However, if the Standard Model changes values over time, and we have reason to suspect it does, because the Cosmological Constant is changing value, THEN it is reasonable to suspect that probabilistic quantum phenomena are driving the changes in our physical "laws", and we would therefore not be able to predict the future of our universe.
So to summarize:
- Our universe is probabilistic at small scales.
- for much of our macro scale phenomenon, the law of large numbers allows us to approximate this probabilistic physics with deterministic laws.
- But for complex structures like life, chaos leverages up the quantum unpredictability
- And while gravity currently dominates our universe, and gravity is deterministic, our best guesses of the underlying physics principles are that our physics will change, so our future is -- unpredictable.