John K Clark <email@example.com> wrote:
> In example with them facing each other the fingers of the two will indeed be
> pointing toward different walls but I don't find that disturbing, if one copy
> was in London and the other in Paris they would also be pointing at
> different walls, but as long as the walls are identical the information
> received from the walls will be the same and no divergence will happen.
> If you have doubts that the information really is the same then convert it
> to a binary sequence and see if the train of ones and zeros is the same.
I finally understand what you are saying. The binary information perceived by the two persons are the same. They stay synchronized and identical because their experiences are symmetrical and identical. You don't care that they are pointing to different walls because their visual views and binary record of the different walls would look identical to them. Both can perceive that they are not pointing toward the same wall, but they both perceive their wall in the same way, and perceive the other wall as being a different wall in the same way.
It is really a clever example to keep the two identical copies synchronized and seeing the same thing. I think we agree that if they pushed through the walls to the outside world, they would diverge? Or if a sound was heard through the walls from one side, they would diverge? Of if a person tried to interact with them, they would diverge? Only by keeping them locked in the perfect room would you call them the same person because they were identical?
For the sake of argument, I will concede that you are right and everything being symmetrical would keep the copies synchronized. As long as they see the same thing and cannot distinguish anything different, they will not diverge.
However, back to the upload example, I think that such a room would be impossible to build in the real world. The fibers in the carpet would have to be exact so it would wear the same way. The walls would have to be internally identical so that they would dent the same way. The table must be purely homogenous so that if broken, it would break perfectly symmetrically. Their clothes would have to be so identical that they wrinkled in the exact same way. Air currents in the room would have to be exactly symmetrical so their hair would become mussed in the exact same way. A piece of glass would have to be so perfectly symmetrical, that it would shatter in a symmetrical pattern when broken. The table legs would have to be so symmetrical, that if broken off and spun like a top, they could not fall in any random direction, but would have to stay standing perfectly balanced in the middle of the room forever.
-- Harvey Newstrom <mailto:firstname.lastname@example.org> Author, Engineer, Entrepreneur, <http://www.gate.net/~harv> Consultant, Researcher, Scientist. <ldap://certserver.pgp.com>