What the Bleep Do We Know!? (stylized as What tнē #$! D̄ө ωΣ (k)πow!? and What the #$! Do We Know!?) is a 2004 American pseudo-scientific film that posits a spiritual connection between quantum physics and consciousness (as part of a belief system known as quantum mysticism). The plot follows the fictional story of a photographer, using documentary-style interviews and computer-animated graphics, as she encounters emotional and existential obstacles in her life and begins to consider the idea that individual and group consciousness can influence the material world. Her experiences are offered by the filmmakers to illustrate the film's scientifically unsupported ideas.

Scientists who have reviewed What the Bleep Do We Know!? have described distinct assertions made as pseudoscience.[9][10] Lisa Randall refers to the film as "the bane of scientists".[11] Amongst the assertions in the film that have been challenged are that water molecules can be influenced by thought (as popularized by Masaru Emoto), that meditation can reduce violent crime rates of a city,[12] and that quantum physics implies that "consciousness is the ground of all being."