Physicist Roger Penrose has spent decades arguing that consciousness isn't something the ...

Theory Briefing

• Penrose's Orch-OR theory is rare among consciousness theories for making predictions testable outside the brain, giving it unusual scientific traction.
• The theory locates consciousness in quantum processes inside microtubules — tiny protein structures found in nearly every cell of the body.
• Most rival theories of consciousness remain untestable by design, making Orch-OR's falsifiability both its boldest claim and its biggest target.
• Decades of debate hinge on whether quantum effects can survive the warm, wet environment of the brain long enough to matter.