Correct me if I'm wrong:
In Frequencies Theo appears to be a determinist (just like the movie's authors), while his father believes in free will and the uncertainty principle.
In the end, when Theo explains "how it all works" and tells his father that as he, Theo, perfects the formula, he'll know everything about the future (no surprises, just enjoying the performance while knowing how it ends), he suggests to his father he should say good-bye; the father agrees and leaves, and seconds later Theo discovers the perfect version of the formula.
Why did his father leave; why the good-bye? Does he hate his son now? Has he renounced him? Why is Theo indifferent? Does his knowledge of the future void all filial emotions somehow?