Biological humans collectively exert at most 400 gigabits/​s of control over the world.

Edit: I now believe that the first paragraph of this post is (at least) not quite right. See this comment for details.

If an agent makes one binary choice per second, no matter how smart it is, there’s a sense in which it can (at best) be “narrowing world space” by a factor of two in each second, choosing the “better half” of possible worlds, from its perspective.

This is the idea behind the reinforcement learning concept of “empowerment”.

People have tried to measure the information throughput of biological humans. The very highest estimates, which come from image recognition tasks, are around 50 bits per second, and most estimates are more like 10 bits per second.

There are about 8 billion living humans. Even if humanity could be perfectly modeled as a single rational agent, and all our choices were perfectly independent of each other, I think this implies that we collectively have no more than about 50 * 8 = 400 billion bits per second of control over the world.