- #1

jcap

- 170

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Consider the following thought-experiment in the many-worlds interpretation.

Suppose that I have a reversible conscious observer AI and a particle with +1/2 spin in the z direction.

Next the observer measures the spin in the x-direction and therefore spits into a version that measures +1/2 and another that measures -1/2.

Now imagine reversing both of the observers, together with the split particle states, so that we end up back with a single observer in the initial state and the particle with +1/2 spin in the z direction.

I think this would be the standard many-worlds interpretation.

But is there a contradiction here?

If both versions of the observer consciously perceive a whole particle with a definite x-spin then when everything is reversed surely we should end up with two particles with x-spin +/- 1/2 rather than one particle with z-spin +1/2?

I think that if many-worlds is true then no reversible machine (i.e. quantum or classical computer) can act as a conscious observer.

In contrast the operation of the brain seems to be fundamentally irreversible; when we consciously measure the spin of a particle our brain and the particle split never to be "put back together again" even in principle. Perhaps conscious awareness of the measurement results are a kind of "guarantee" that the evolution of the branches of the wavefunction will never be reversed in the future.

Suppose that I have a reversible conscious observer AI and a particle with +1/2 spin in the z direction.

Next the observer measures the spin in the x-direction and therefore spits into a version that measures +1/2 and another that measures -1/2.

Now imagine reversing both of the observers, together with the split particle states, so that we end up back with a single observer in the initial state and the particle with +1/2 spin in the z direction.

I think this would be the standard many-worlds interpretation.

But is there a contradiction here?

If both versions of the observer consciously perceive a whole particle with a definite x-spin then when everything is reversed surely we should end up with two particles with x-spin +/- 1/2 rather than one particle with z-spin +1/2?

I think that if many-worlds is true then no reversible machine (i.e. quantum or classical computer) can act as a conscious observer.

In contrast the operation of the brain seems to be fundamentally irreversible; when we consciously measure the spin of a particle our brain and the particle split never to be "put back together again" even in principle. Perhaps conscious awareness of the measurement results are a kind of "guarantee" that the evolution of the branches of the wavefunction will never be reversed in the future.

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