LEVEL 1
Where an identical Earth exists
The simplest multiverse is one that most certainly exists – the Big Bang model of cosmic origins predicts that every point in the universe has a ‘Hubble volume’ around it, limited by the expansion of the universe and the distance light has been able to travel in the 13.8 billion years since the infant universe became transparent. In practice, this means our Hubble volume is a sphere 93 billion light years across, but there are many more Hubble volumes extending far beyond what we can see. If the universe has a closed geometry, the number is limited as space curves back around on itself, but if the universe is open, as seems most likely, there may be an infinite number of Hubble volumes, each containing a universe, meaning that somewhere out there, other planets virtually identical to Earth exist.