> Maybe in making the eggs and toast, you leave the house a second later, and a driver that ran a stop sign that would have hit you passes in front of you inste

> Maybe in making the eggs and toast, you leave the house a second later, and a driver that ran a stop sign that would have hit you passes in front of you instead. This is likely unimportant to answer the questions that the simulator is supposed to answer, which means that no one would ever bother running one ancestor simulation--as you define it--when they could instead run multiple trials of a different kind of simulation for the express purpose of eliminating such confounding "want of a nail" moments. "We ran this ancestor simulation for 10 million years to find out what logfromblammo would eat for lunch on 13 August, 2018, and the results were ruined when the simulated logfromblammo was killed in traffic that very morning, just before the entire simulator planet was demolished to make way for a hyperspace bypass. We'll check the budget to see if we can reset for another run." Maybe the other driver also had a breakfast that delayed their departure by one second, and now they hit me again. In one ancestor simulation, you won't know all the various circumstances that contribute to the causation of an event. If you do cut corners, you can say that there is an X% chance on any given day that I get involved in a traffic collision. So an ancestor simulation--as you define it--is functionally identical to walling off a piece of your own universe, rearranging matter inside it to conform to initial conditions, and then watching it to see what happens. If your universe is itself a simulation, how does the parent universe detect the difference between someone running a simulation and Magrathean-scale engineering projects? If I commission a planet that is a perfect copy of Earth on the day before Lincoln was assassinated, and black-bag Booth an hour before he shows up at the theater, is that an ancestor simulation? Do I need to wrap it in a perfectly black shell and project sunlight and starlight through it from time-appropriate locations? That only requires that the star you use for energy is a bit more energetic than the sun. If you simulate a planet that predates astronomy, perhaps to see what would happen if dinosaur-like creatures hadn't been wiped out, you wouldn't even need to do that. Your total energy requirements for the lifetime of the simulation are the delta-v required to build an Earth-like planet with a Moon-like moon and move it into an Earth-like orbit around a Sol-like star. We wouldn't be able to detect if our planet is a simulation by dinosaurs, to see what would have happened if their planet had suffered an extinction-level event before they launched themselves into space. How do you tell the difference between a naturally-formed and artificially-constructed planet? Likewise, how do you distinguish between someone trying to compute an ancestor simulation and someone just running an immersive MMORPG? If you did create a single ancestor simulation larger than a few interacting atoms, it rapidly loses its scientific power, due to all the variables you intentionally did not constrain. How is that not just an amusement park?