Exact replica of our Earth 

 is populated by clones. 



You are here 



Earthlike planet has collapsed 

 to form a black hole. 



Dinosaurs still reign because no 

 asteroid hit this earthlike planet. 



Island universe in which we live encompasses infinitely many ob- 

 servable regions, or "O-regions, " each the size of our observable 

 universe. Each sphere in the schematic diagram represents a re- 

 gion whose radius is equal to the distance from Earth to the most 

 distant objects we can see: about 40 billion light-years. The Earth 

 lies inside one such O-region. Because of the "graininess" of space 

 and time in quantum mechanics, the number of possible histories 

 of all the particles inside such a region, beginning with some fixed 

 moment in the past, is finite (though, of course, huge). Since the 

 number of O-regions is infinite, every possible history — a world in 



which Earth collapses to form a black hole, for instance, or a world 

 in which the dinosaurs still survive — is replayed in an infinite num- 

 ber of O-regions, the closest ones at least a googolplex (10 to the 

 power 10 wo ) light-years away. The O-regions are all shown at the 

 same time after the big bang, which corresponds to an "internal 

 view" of the island universe. The internal view is used only to por- 

 tray the O-regions that make up part of the interior of one island; 

 the other islands would not be visible in a consistent diagram, but 

 in the "global view" that has been overlaid on this drawing, several 

 other island universes appear. 



