Although he was acquainted with the metaverse of Neal Stephenson's novel Snow Crash, Rosedale has claimed that his eyesight of digital worlds predates that e book, and that he executed early digital world experiments all through his higher education yrs at the University of California, San Diego, where he researched physics. Br Med J 1:1249–1250. Kato I, Akhmedkhanov A, Koenig K, Toniolo PG, Shore RE, Riboli E. 1997.