This Twist on Schrödinger’s Cat Paradox Has Major Implications for Quantum Theory

A laboratory demonstration of the classic “Wigner’s friend” thought experiment could overturn cherished assumptions about reality

At a quantum level observation brings reality into existence, but what happens when the observer also gets observed, well, it seems there can be two different realities, so one scientist may see an electron spinning up, while the other sees it spinning down.

Does an objective world actually exist, and will quantum physics need to be abandoned?

The second article is a bit easier to understand. 

Now Tischler and her colleagues have carried out a version of the Wigner’s friend test. By combining the classic thought experiment with another quantum head-scratcher called entanglement—a phenomenon that links particles across vast distances—they have also derived a new theorem, which they claim puts the strongest constraints yet on the fundamental nature of reality. Their study, which appeared in Nature Physics on August 17, has implications for the role that consciousness might play in quantum physics—and even whether quantum theory must be replaced.

Scientific American 

This Twist on Schrödinger’s Cat Paradox Has Major Implications for Quantum Theory


Quantum reality is either weirdly different or it collapses


This is a relatively simple experiment to do, so Wigner grabs his friend, Alice, and places her in a sealed laboratory. Alice measures the spin of a stream of electrons that are prepared in a superposition state. Wigner is outside the laboratory and will measure the entire laboratory. Alice, before passing out, determines that an electron is spin-up. But Wigner hasn’t made a measurement, so he sees Alice in a superposition of having measured spin-up or spin-down. When Wigner makes his measurement, hypothetically, he could end up with a result where Alice measured spin-down when in fact she measured spin-up.

Quantum reality is either weirdly different or it collapses