I don’t buy your first argument against time-travel. Even under the model of the universe as a static mathematical object connected by wave-function consistency constraints, there is still a consistent interpretation of the intuitive notion of “time travel”:
The “passage” of time is the continuous measurement of the environment by a subsystem (which incidentally believes itself to be an ‘observer’) and the resulting entanglement with farther away parts of the system as “time goes on” (i.e. further towards positive time). Then time-travel is a measurement of a “past” state or described differently (but the same thing) an entanglement between a subsystem (the location in the past the traveler visited) and its surroundings, which does not respect the common constraint that entanglement propagates at speed of light (because the traveler came from some future location (and its past light-cone) which is—“surprisingly”—entangled with the past). While violating common understanding of space-time, it is not logically impossible in this understanding of the universe.
This time-travel allows interaction with the past (which are not different from observations anyway).
No, what you say is correct, but you don’t even need to bring entanglement into it at all: moving faster than light is the same thing as moving into the past (in some reference frame). This is why information can’t propagate faster than light.
The kind of time travel that I’m talking about here is not merely sending information into the past but sending yourself into the past, that is, sending your body into the past. But that’s not possible because your body is on the most fundamental level made of entanglements, and entanglements define the arrow of time.
I don’t buy your first argument against time-travel. Even under the model of the universe as a static mathematical object connected by wave-function consistency constraints, there is still a consistent interpretation of the intuitive notion of “time travel”:
The “passage” of time is the continuous measurement of the environment by a subsystem (which incidentally believes itself to be an ‘observer’) and the resulting entanglement with farther away parts of the system as “time goes on” (i.e. further towards positive time). Then time-travel is a measurement of a “past” state or described differently (but the same thing) an entanglement between a subsystem (the location in the past the traveler visited) and its surroundings, which does not respect the common constraint that entanglement propagates at speed of light (because the traveler came from some future location (and its past light-cone) which is—“surprisingly”—entangled with the past). While violating common understanding of space-time, it is not logically impossible in this understanding of the universe.
This time-travel allows interaction with the past (which are not different from observations anyway).
Do I overlook something here?
No, what you say is correct, but you don’t even need to bring entanglement into it at all: moving faster than light is the same thing as moving into the past (in some reference frame). This is why information can’t propagate faster than light.
The kind of time travel that I’m talking about here is not merely sending information into the past but sending yourself into the past, that is, sending your body into the past. But that’s not possible because your body is on the most fundamental level made of entanglements, and entanglements define the arrow of time.