everything in the next moment is predetermined by the trajectory of atoms

Not exactly, the quote "God does not play dice with the universe" is from Einstein and is does not make reference to the literal "Jewish-Christian God", but instead to nature, the universe and it's laws (Pantheism). What Einstein meant then, is that nature and it's classical Physical mechanics are deterministic, in response to quantum physics and it's indeterminism, like the "Copenhagen interpretation" or like "Heisenberg's uncertainty principle" . This assessment has been point out by many physicists as Einstein's biggest mistake, as experiments have demonstrated that we can only know a probability of the result of a quantum system, but never the answer. For an attempt to figure out the variables would mean an interaction with the system, which would create a collapse of the way function or, in other words, it would cease from being in a quantum estate. So, as the French physicist Serge Haroche said "God does play dice", there is indeterminism in the universe.

If we apply this to the series, the universe sees random Quantum fluctuations and it can great virtual particles, which is a particle and an antiparticle being created from "nothing" and then nullifying themselves so they don't violated the law of conservation of energy. But, what Hawking theorized is that the radiation from black holes is a bunch of virtual particles created in the event horizon (a sort of "edge of the black hole"), where one particle is absorbed by the hole and the other remains outside, transforming into a real particle as a result. In the case of Sonny boy, at random, one group of kids is in "reality"and the other is in the island or black hole, let's remember that in the first episode the school was literally covered in darkness. Of course, humans don't follow quantum physics because we are not quantum objects, so takes this interpretation like a thought experiment, similar to Schrodinger's cat.

I hope I explained myself well, English is not my first language so I apologize for any mistake.