Originally Posted by interesting

The following is a clear implication of the many worlds hypothesis. It is simply that for any person up to any point in time there may be multiple universes with vastly different histories, but which have in common that person's life history. So, if you consider the history of the world, there is not one answer. Or if you see someone walking down the street and consider what their life history is or consider all the scinerios surounding your life there will not be a uniform answer. Surely this concept was known to the ancients, but why is it not discussed in philosophy or physics books?
I came up with an experiment to definitively test the many worlds hypothesis which if correct, produces a device that acts like magic. It may also provide the principal behind an information time machine. I don't believe a time machine could be this simple. I present this as an experiment in logic. I believe Stephen Hawking already knows about time machines and the type of time travel obtained by my design is not the model explained in his book The Future of Spacetime. Perhaps the theory of time travel invalidates the many worlds hypothesis.
Consider a box consisting of a light source that emits single photons at a time, a beam splitter, and an array of photomultipliers. The beam splitter splits the light source into n + 1 paths. N of the photomultipliers are connected to a red light out of the box, and one is connected to a blue light out of the box. According to the many worlds hypothesis, once a photon passes through the beam splitter, n + 1 universes are formed – one universe in which the photon is detected by the photomultiplier connected to the blue light, and we get a blue flash, and n universes in which the photon is detected by a photomultiplier connected to the red light, and we get a red flash. After each emission, the n universes in which the red light flashes will be identical on the outside of the box. Thus, according to the many worlds hypothesis, once the light source is turned on, an observer would in general get a 1:1 ratio of red to blue flashes, no matter what number n is. This is difficult to explain, but the following may be helpful. Suppose n = 1; after a series of emissions an observer would in general get a 1:1 ratio of red to blue flashes; now suppose we just add on to this scenario identical universes in which the red light flashes. We get the same situation. Thus, we obtain a device that if the many worlds hypothesis is correct, acts like magic. Suppose each photomultiplier is connected to a light in the box that indicates which photomultiplier detects a photon. If the box is closed and we do not look in it, an observer would get a 1:1 ratio of red to blue flashes. However, once the box is opened an observer would get a n:1 ratio of red to blue flashes.
Suppose the box remains closed and a recording device is kept in the box that records which photomultipler sets off a red flash. After a series of emissions, the decision is made to either erase or read the device's log of detections. If the information is erased, an observer would have gotten a 1:1 ratio of red to blue flashes. However, if the information is read, an observer would have gotten a 1:n ratio of blue to red flashes. Thus, an information time machine is obtained!