[marmaglade]

The hitchhiker's paradox is correct, taking a point and looking backward or forward will correctly give an average event 10 minutes away, but combining the events to give an average of 20 minutes is false. Two events have been chosen resulting in a conditional probability.

Put more clearly, an event happens on average 10 minutes in the past, but using the same starting point for the event in the future links the events with a dependency. We could also arbitrarily start looking forward at the instance of the event in the past, or another random point in time.

[gowld]

This is simply incorrect, and the (hypothetical) burden is on you to disprove the theoretical and empirical results that have been shown to prove the solution.

The conditional probability is equal to the unconditional probability, specifically because the Poisson model (which Bitcoin hashing approximates) is a model of fully independent events.