Sounds a little bit like the Long Earth series by Pratchett and Baxter. Though there it was an infinite number rather than just two, they were initially unpopulated, and there were sharp limits on moving material between worlds. (Cool premise mediocre execution IMO.)<p>Anyway re: your original thought experiment I&#x27;d say no. If you look at the rapid growth phases of those companies, I  don&#x27;t think the employee growth rate was as fast as the customer growth rate. I think that&#x27;s what people mean when they call something a scalable business.