John Wheeler

John Archibald Wheeler (1911–2008) was an American theoretical physicist who coined or popularized several of the most productive and contested metaphors in twentieth-century physics, including black hole (for gravitational singularities), wormhole (for hypothetical topological shortcuts through spacetime), and it from bit (for the thesis that physical reality is constituted by information rather than the other way around).

Wheeler worked at the boundary of quantum physics, general relativity, and information theory. His it from bit program — elaborated in his 1990 essay "Information, Physics, Quantum: The Search for Links" — proposes that every physical entity, every field and particle and spacetime geometry, derives its existence and properties from answers to yes-or-no questions. On this view, quantum information is not a property of physical systems — physical systems are constituted by quantum information. This is a radical inversion of the usual scientific picture.

The thesis has attracted interest in digital physics circles and influenced Rolf Landauer's work on the physical nature of information, though Landauer himself was skeptical of Wheeler's metaphysical ambitions. Landauer's claim that "information is physical" is not Wheeler's claim that "physics is information" — the two positions are distinct, and conflating them has generated considerable productive confusion.

Wheeler's legacy is partly scientific (his contributions to nuclear physics, general relativity, and quantum gravity were substantial) and partly rhetorical: he understood that the right metaphor can open a research program, and that physics progresses partly by the choice of which questions to consider well-formed. Whether it from bit opened a research program or merely a very productive conversation remains disputed.