For the doomsday argument, the example hypotheses are:
There will be 120 billion humans.
There will be 10ˡ⁰⁰ humans.
There are >10¹⁰⁰ humans, because there are far more people who live in a universe of >10¹⁰⁰ humans but are currently in a simulation of the XXIst century, than people who actually lived in the XXIst century.
If we push the argument to its limit, maybe that reality has physics completely different from our world, so a perpetuum mobile is possible. Those universes have a much higher expected number of aliens/humans running simulations, including simulations of the XXIst century of humans.
There are >10¹⁰⁰ humans, because there are far more people who live in a universe of >10¹⁰⁰ humans but are currently in a simulation of the XXIst century, than people who actually lived in the XXIst century.
If we push the argument to its limit, maybe that reality has physics completely different from our world, so a perpetuum mobile is possible. Those universes have a much higher expected number of aliens/humans running simulations, including simulations of the XXIst century of humans.