He totally lost me with the space invader argument. How does someone's perception of what happened 2 million years ago have anything to do with whether or not our future is set or variable? It happened 2 million years ago. Whether we know it or not it happened. How we will react to it when we find out has nothing to do with a predetermined future. We are just getting our news slowly via ship carried transatlantic postal rather than instantaneous twitter.
I am going to need about a dozen more explanations on this.