From a phsyics point of view, the universe is governed by probalities.. and is not deterministic
I'd love to know who started this rumour as it is completely untrue...
Probabilities play a role in *observations* of the universe, but the universe itself is totally deterministic (as in our current understanding of the laws of phsyics show them to be completely deterministic)
I can believe that some would think that Popper suggested that, but I wouldn't have thought Popper sufficiently ignorant of physics to actually think it. It's a typical layman science book misinterpretation, most usually of quantum mechanics.
As far as we are aware, the universe evolves deterministically.
Well, Hawking (no s) used to adamantly insist that even weak determinism was untrue (in a reverse kind of way). He has since recanted, though not before making a lot of enemies (look up "black hole information problem" for more details)
any event can be rationally predicted
Here we run into difficulties with what we are calling an "event". An event is actually usually an observation. Where the distinction is blurred at classical levels, we have no problems anyway. But the prediction of a particular state of a wave-function is indeed stongly deterministic, with the following caveat:
Popper's definition is also problematic in the use of "desired" and "sufficient". Mathematically, there is no "sufficent" accuracy in a chaotic system that will necessarily reveal a non-chaotic sub-region. However, we do not usually consider chaos a barrier to determinism. It is a limitation of measurement and/or calculation. It does not constitute a property of the universe per se.
The universe being deterministic is not about what *we* can say/predict, but is concerned with future events being determined *solely* by past events - it is a point of causality. Which of course has major implications for choice and free-will...
The problem in hand is the universe, BECAUSE it hasn't always existed.
Something that has always existed (God), by definition, requires no explanatory causes.
Both of these statements are rather naive and redundant these days with a current understanding of space and time. Time is not the absolute yardstick that was imagined when such arguments were put forward.
An infinite universe requires as much or as little cause as a finite one. Similarly with God. God requires no explanatory cause as we define him as that entity which has no prior cause. It has nothing to do with him "always existing" which is a fairly meaningless statement with regard to our concept of time.