I would like to object to the variance explanation: in the Everett interpretation there was not even one collapse since the Big Bang. That means that every single quantum-ly random event from the start of the universe is already accounted in the variance. Over such timescales variance easily covers basically anything allowed by the laws: universes where humans exist, universes where they don’t, universes where humans exist but the Earth is shifted 1 meter to the right, universes where the start of Unix timestamp is defined to start in 1960 and not 1970, because some cosmic ray hit the brain of some engineer at exactly the right time, and certainly universes like ours but you pressed the “start training” button 0.153 seconds later. The variance doesn’t have to stem from how brains are affected by quanum fluctuations now, it can also stem from how brains are affected by regular macroscopical external stimuli that resulted from quantum fluctuations that happened billions of years ago.
I would like to object to the variance explanation: in the Everett interpretation there was not even one collapse since the Big Bang. That means that every single quantum-ly random event from the start of the universe is already accounted in the variance. Over such timescales variance easily covers basically anything allowed by the laws: universes where humans exist, universes where they don’t, universes where humans exist but the Earth is shifted 1 meter to the right, universes where the start of Unix timestamp is defined to start in 1960 and not 1970, because some cosmic ray hit the brain of some engineer at exactly the right time, and certainly universes like ours but you pressed the “start training” button 0.153 seconds later. The variance doesn’t have to stem from how brains are affected by quanum fluctuations now, it can also stem from how brains are affected by regular macroscopical external stimuli that resulted from quantum fluctuations that happened billions of years ago.