The question in class was, "if the block universe theory is true, does that mean determinism is true?" (I think. I'm working from memory. Let me know if I've misunderstood.)

My answer is no. What is determinism? Well, maybe different people mean different things. Here's what I took it to be:

The universe is deterministic if and only if: the state of the world at any one time, together with the laws of nature, "fixes" the state of the world at all other times. More carefully, for those who are fans of logic: the set containing a sentence describing the state at one time and a bunch of sentences that together capture the laws of nature, entails, for each time t, a sentence describing the state of the world at t.

Now suppose the block universe theory of time is true. Then there is a complete description of reality from an "atemporal" perspective. That description might contain the following sentence: "At noon on January 1st, 2040, a silver atom is sent through a stern-gerlach magnet. Slightly later, it is deflected upward."

The truth of sentences like these does not mean that determinism is true. The fact that the atom is deflected up on that day is compatible with the following fact: the past state of the world together with the laws did not "predetermine" that atom would be deflected up. It can be true that the atom is deflected up on that day even if this truth is not entailed by sentences about earlier times and sentences stating the laws of nature.