In the late 1970s, legendary physicist John Wheeler proposed a radical question: Exactly when does the universe notice that we're paying attention to a quantum experiment? And does it really matter?

Figure 1: Schematics of Wheeler’s delayed-choice experiments. Here, we report the first realization of Wheelers famous delayed-choice gedanken experiment with single massive particles. The only ...

Does the universe notice that we're paying attention to a quantum experiment? The answer goes against everything we thought we knew. When you purchase through links on our site, we may earn an ...