Some theories hold that reality and consciousness are one and the same. Is the universe really all inside your head
Descartes might have been onto something with “I think therefore I am”, but surely “I think therefore you are” is going a bit far? Not for some of the brightest minds of 20th-century physics as they wrestled mightily with the strange implications of the quantum world.
According to prevailing wisdom, a quantum particle such as an electron or photon can only be properly described as a mathematical entity known as a wave function. Wave functions can exist as “superpositions” of many states at once. A photon, for instance, can circulate in two different directions around an optical fibre; or an electron can simultaneously spin clockwise and anticlockwise or be in two positions at once.
When any attempt is made to observe these simultaneous existences, however, something odd happens: we see only one. How do many possibilities become one physical reality?
This is the central question in quantum mechanics, and has spawned a plethora of proposals, or interpretations. The most popular is the Copenhagen interpretation, which says nothing is real until it is observed, or measured. Observing a wave function causes the superposition to collapse.
However, Copenhagen says nothing about what exactly constitutes an observation. John von Neumann broke this silence and suggested that observation is the action of a conscious mind.