In a recent paper, Żukowski and Markiewicz showed that Wigner's Friend (and, by extension, Schrödinger's Cat) can be eliminated as physical possibilities on purely logical grounds. I validate this result and demonstrate the source of the contradiction in a simple experiment in which a scientist S attempts to measure the position of object $|O\rangle = |A\rangle_S + |B\rangle_S$ by using measuring device M chosen so that $|A\rangle_M \approx |A\rangle_S$ and $|B\rangle_M \approx |B\rangle_S$ . I assume that the measurement occurs by quantum amplification without collapse, in which M can entangle with O in a way that remains reversible by S for some nonzero time period. This assumption implies that during this "reversible" time period, $|A\rangle_M \neq |A\rangle_S$ and $|B\rangle_M \neq |B\rangle_S$ -- i.e., the macroscopic pointer state to which M evolves is uncorrelated to the position of O relative to S. When the scientist finally observes the measuring device, its macroscopic pointer state is uncorrelated to the object in position $|A\rangle_S$ or $|B\rangle_S$ , rendering the notion of "reversible measurement" a logical contradiction.In a recent paper, Żukowski and Markiewicz showed that Wigner's Friend (and, by extension, Schrödinger's Cat) can be eliminated as physical possibilities on purely logical grounds. I validate this result and demonstrate the source of the contradiction in a simple experiment in which a scientist S attempts to measure the position of object $|O\rangle = |A\rangle_S + |B\rangle_S$ by using measuring device M chosen so that $|A\rangle_M \approx |A\rangle_S$ and $|B\rangle_M \approx |B\rangle_S$. I assume that the measurement occurs by quantum amplification without collapse, in which M can entangle with O in a way that remains reversible by S for some nonzero time period. This assumption implies that during this "reversible" time period, $|A\rangle_M \neq |A\rangle_S$ and $|B\rangle_M \neq |B\rangle_S$ -- i.e., the macroscopic pointer state to which M evolves is uncorrelated to the position of O relative to S. When the scientist finally observes the measuring device, its macroscopic pointer state is uncorrelated to the object in position $|A\rangle_S$ or $|B\rangle_S$, rendering the notion of "reversible measurement" a logical contradiction.

arXiv:2202.07111Feb 15, 20220 citations

Last Work with Walter

Karl Hess

Before our publication of (Hess and Philipp, 2004), my inaugural paper for the National Academy of Sciences, Walter and I organized a meeting at the Beckman Institute of the University of Illinois to present all of our ideas and to discuss them with the experts. The meeting was a disappointment for me, because not many of the scientists who had criticized us came. Tony was present and discussed his opposing views. I do not remember any other discussions that we had not heard before, and the presentations that Walter and I gaveweremathematically too complex. Our adversaries did not like what we said; only our friends did. Andrei Khrennikov and also Louis Marchildon were present and very supportive.Before our publication of (Hess and Philipp, 2004), my inaugural paper for the National Academy of Sciences, Walter and I organized a meeting at the Beckman Institute of the University of Illinois to present all of our ideas and to discuss them with the experts. The meeting was a disappointment for me, because not many of the scientists who had criticized us came. Tony was present and discussed his opposing views. I do not remember any other discussions that we had not heard before, and the presentations that Walter and I gaveweremathematically too complex. Our adversaries did not like what we said; only our friends did. Andrei Khrennikov and also Louis Marchildon were present and very supportive.

Oct 22, 20140 citations

Albert Einstein, Boris Podolsky, and Nathan Rosen

Albert Einstein, Boris Podolsky, N. Rosen

Princeton University Press eBooksSep 25, 20173 citations

|O\rangle = |A\rangle_S + |B\rangle_S

by using measuring device M chosen so that

|A\rangle_M \approx |A\rangle_S

and

|B\rangle_M \approx |B\rangle_S

. I assume that the measurement occurs by quantum amplification without collapse, in which M can entangle with O in a way that remains reversible by S for some nonzero time period. This assumption implies that during this "reversible" time period,

|A\rangle_M \neq |A\rangle_S

and

|B\rangle_M \neq |B\rangle_S

-- i.e., the macroscopic pointer state to which M evolves is uncorrelated to the position of O relative to S. When the scientist finally observes the measuring device, its macroscopic pointer state is uncorrelated to the object in position

|A\rangle_S

|B\rangle_S

, rendering the notion of "reversible measurement" a logical contradiction.