The Information Argument

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Imagine a universe with two similar rooms, called room0 and room1. In room0 there is a closed note with ‘0’ written on it, and in room1 there is a closed note with ‘1’ written on it.

You are in one of these two rooms, but you don’t yet know which one, because you have not yet opened the note in your room.

There is also someone in the other room. As it happens, this person’s physical body is identical to yours “down to the quark”.

Whether you are in room0 or in room1 makes no difference to the state of the physical universe in this scenario, because in either event, there are two physical bodies exactly like yours in two specific locations.

Since the state of the physical universe is the same in both cases, it does not contain information about which room you are in.

Yet this information does exist, for you can learn it by reading the note in your room.

6 Responses to “The Information Argument”

• david says:

You know nothing more, because you don’t know if you are the initial you or the copy. Otherwise the copies are not identical.

Regardless of who you are…
1. Before reading the note, you could not know which room you were in, even if you knew the state of the entire physical universe.
2. After reading the note, you know which room you were in.
Which of the above do you disagree with?

• Tonio says:

If you ever played video games, this akin to saying that there is a game state, and you can have the point of view of either player 1 or player 2 or none of them (spectator). Surely the game world is indistinguishable from whether you’re viewing it from player 1 or 2 point of view. But the universe is not the game world, it also includes the person sitting at their computer.

I call this the fallacy of “outsider view”. You’re making the thought experiment but the fact is that we’re not talking about identical universes, we’re only talking about thought experiments. You’re looking at the universe from the outside, i.e. as if you are researcher doing some experiment on some closed system. The problem is that this is never true, as you are forever part of the system you’re studying.

So the answer to your question, “where did that information come from whether I am in room0 or room1”, is that the information came from me when I imagined your thought experiment and pretended to be the person in room0 or room1. As far as I know, I’m part of the universe just like you are.