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"It from bit"
1989· Idea
PhilosophyAn argument about reality that science can't test (yet).
John Wheeler's 1989 slogan that every physical thing ultimately arises from information: answers to yes/no questions.
See it on the Science map →How it works
Wheeler noticed that in quantum physics a particle's properties are not fixed until something measures them, and each measurement yields a yes/no answer: a bit. He proposed turning this around: every "it" (particle, field, even spacetime) gets its existence from bits registered by measurements. On this view information is not about the world; it is what the world is made of. Wheeler called it an idea to explore, not a finished theory.
Why it matters
It inspired quantum information science and the habit of treating information as physics' most basic currency. It is the philosophical root of much later work.
How we know
None directly. It is philosophy. Quantum experiments, including tests of Wheeler's delayed-choice idea in 2007, match quantum theory but do not prove that reality is made of bits.
Still a mystery
What a bit is "about" if there is nothing beneath it, and who or what asks the yes/no questions, are unanswered.
Connections (3)
▸Information is physical leads to "It from bit"Philosophy
The relationship
Landauer showed that information always lives in physical stuff. Wheeler flipped the direction: maybe physical stuff ultimately comes from information. The first claim is measured physics; the second is a philosophical extension that treats bits, not particles, as the basic ingredient.
How the link was found
John Wheeler made the leap in 1989, drawing on Shannon's information theory, Landauer's work and quantum measurement.
Is it proven?
The first direction is proven by experiments such as the 2012 measurement of Landauer's limit. The reverse direction is unproven philosophy.
Open questions and mysteries
Can bits exist without something to be bits of? That chicken-and-egg question has no settled answer.
▸John Wheeler coined "It from bit"Philosophy
The relationship
Late in his career Wheeler concluded that quantum measurement, which turns possibilities into definite yes/no answers, might be the foundation of reality itself. He condensed this into the slogan "it from bit" and challenged physicists to build physics from information upward.
How the link was found
John Wheeler, in a 1989 paper "Information, Physics, Quantum: The Search for Links."
Is it proven?
It is a philosophical program, not a tested theory. It strongly influenced quantum information research, but no experiment shows reality is made of bits.
Open questions and mysteries
Wheeler hoped observers collectively create reality; how that could work without circular reasoning remains unclear.
▸"It from bit" is a close cousin of The simulation hypothesisPhilosophy
The relationship
Both ideas put information at the bottom of reality. "It from bit" says the world is built from yes/no answers. The simulation hypothesis adds a computer running the code and someone who built it. Take Wheeler's idea and add a programmer, and you are close to the simulation picture.
How the link was found
Wheeler (1989) and Bostrom (2003) developed them separately; later writers, including Bostrom's commentators, drew the comparison.
Is it proven?
Neither idea is tested, and both are philosophy. Their similarity is conceptual, not demonstrated.
Open questions and mysteries
If reality is information, does it need a computer at all? Wheeler thought not; simulation fans think so.