Physicists Disagree Wildly on What Quantum Mechanics Says About Reality

A Nature survey of more than 1,100 physicists reveals fundamental disagreements about quantum mechanics’ relationship to reality, despite the theory’s century-long track record as one of science’s most successful frameworks. The survey, conducted to mark quantum mechanics’ 100th anniversary, found 36% of researchers favor the Copenhagen interpretation while 17% prefer epistemic approaches that treat quantum states as information rather than physical reality.

Another 15% support the many-worlds interpretation. Researchers split evenly on whether a boundary exists between quantum and classical worlds — 45% said yes, 45% said no. When asked about the wavefunction’s nature, 47% called it a mathematical tool while 36% considered it a representation of physical reality. Only 24% of respondents expressed confidence their chosen interpretation was correct, with others viewing their preference as merely adequate or useful in certain circumstances.

The survey contacted over 15,000 researchers whose recent papers involved quantum mechanics, plus attendees of a centenary meeting on Heligoland island. Despite quantum mechanics enabling technologies from computer chips to medical imaging, physicists remain divided on the physical reality underlying the mathematics.