Here is a link to the scientific paper: http://www.simulation-argument.com/simulation.html The paper is long, so I will summarize the argument here. Given that our brains are made from nothing but nueron connections and such, it would be possible to engineer a computer as to simulate nueral connections to create counciousness. If in the distand future humans have enormous computational powers, they could be able to set up a simulation of humankind and the universe around them (either modeled on themselves or an altered version of themselves). The beings in the simulation would have no way of knowing if they were in a simulation or not. Massive numbers of simulations could be produced with their computational power, in effect many more people than actually exist in reality. It is therefore a high probability that we ourselves are nothing but in the simulation. The other options are that humanity will destroy itself before being able to attain the computational power, or that future humanity will have no motivation to do simulations because their knowledge is so advanced that they will not gain any information from the simulation. They may regard recreational adtivities as nothing but inefficient ways to attain pleasure (which may alternatively be acheived by direct stimulation of pleasure neurons with their future technology).