The Multiverse May Be Real | David Deutsch

David Deutsch argues that modern academic institutions and grant systems are structurally hostile to fundamental research, favoring incremental work over transformative breakthroughs, and that this bias stifles the kind of curiosity-driven science responsible for humanity’s greatest advances.

• Einstein would likely fail a modern grant application because review panels lack expertise in novel fundamental ideas and default to evaluating proposals based on familiar, incremental criteria.
• Grant systems fund projects rather than people, forcing researchers to justify work in predefined categories (checkboxes), which makes it impossible to propose entirely new fields like quantum computing before they exist.
• Universities impose rigid hierarchies, teaching loads, and administrative rules (e.g., anti-nepotism policies, clocking-in requirements) that suppress the autonomy and passion essential for creative research.
• Government funding, while well-intentioned, has crowded out diverse private funding sources and imposed uniform bureaucratic criteria that even private charities now mimic, reducing the variety of approaches to supporting science.

Deutsch advocates for a funding model centered on individuals rather than projects, where a trusted researcher is given broad freedom to pursue their interests and to hire collaborators directly.

• He proposes flat research groups led by a principal investigator who is funded based on their track record and passion, not on detailed project proposals.
• The leader would use grant money to hire postdocs, grad students, and others as equals in a joint creative endeavor, with everyone encouraged to work on what excites them.
• He cites the Conjecture Institute as a promising example of an organization that funds people rather than projects and focuses on foundational work.
• He encourages wealthy patrons to identify and fund passionate individuals directly, arguing that diversity of funding sources and philosophies is more important than any single correct approach to selecting research.

Deutsch distinguishes between fundamental research (which generates knowledge needed across many fields) and foundational research (which drills into the deep bases of a specific field), but sees both as united by the driving force of curiosity and interest.

• He argues that the entire edifice of scientific and technological progress is an indivisible whole powered by curiosity, and that suppressing fundamental inquiry anywhere risks weakening progress everywhere.
• He rejects the utilitarian argument that fundamental research should be funded only because it eventually yields practical applications, insisting instead that the impulse to create knowledge is valuable in itself and cannot be safely compartmentalized.
• He acknowledges that incremental research is important and not to be disparaged, but warns that the current system’s heavy bias against the fundamental means that transformative work is increasingly done in researchers’ spare time rather than as their primary funded activity.

On quantum gravity, Deutsch is skeptical of string theory’s approach, which he sees as starting from mathematical structures rather than from a clear physical problem, and he has explored his own alternative called qubit field theory.

• He identifies a deep conceptual incompatibility between quantum field theory (which assumes a fixed background spacetime) and general relativity (which treats spacetime itself as dynamical), arguing that this is more fundamental than the technical problem of non-renormalizability.
• He points to a specific contradiction in quantum field theory: the axiom that field quantities at spacelike-separated points must commute, even though they fail to commute at the same point, which he believes is the root cause of the theory’s infinities.
• His qubit field theory replaces continuous field values with qubits at each point, eliminating infinities and non-localities, but he has been unable to solve the measurement problem for this theory and has not published it formally beyond the arXiv.
• He criticizes string theory for working backward from mathematical objects to physical meaning, contrasting this with the historical pattern in physics where a conceptual problem (e.g., the nature of spacetime) precedes and guides the search for the right equations.

Deutsch’s interpretation of quantum mechanics is firmly Everettian (many-worlds), and he considers it essential to his own discovery of quantum computing.

• He had a personal lunch with Hugh Everett in Austin in the 1970s and reports that Everett was enthusiastic about parallel universes, contrary to the myth that he avoided that language; Everett left physics to pursue optimization consulting and make a fortune, not because of academic rejection.
• He explains that branches are not fundamental entities that split at a moment but emergent properties: a continuum of universes exists at all times, but they only become worth calling separate “worlds” when they evolve independently after decoherence (e.g., after a measurement).
• Branch recombination is simply interference: when branches are not yet causally autonomous, they affect each other, and it is incorrect to speak of separate universes during interference phenomena.
• He derives the Born rule (probabilities in quantum mechanics) from decision theory combined with quantum theory without probability, showing that a rational agent in a branching universe would make decisions as if the Born rule holds, without needing to postulate it as a separate axiom.

Deutsch maintains that free will is real but has nothing to do with quantum mechanics; it is about the creation of new knowledge, which is an emergent phenomenon that does not violate physical laws.

• He argues that when humans make creative choices—whether in science, language, or daily decisions—they bring genuinely new knowledge into the world that did not exist before, even at the Big Bang.
• This creativity is not about violating physical laws at the level of particle trajectories but about emergent-level novelty in knowledge and explanation.
• He rejects both the claim that free will is an illusion and the claim that it requires quantum indeterminacy, seeing both positions as lacking any actual theory.

On constructor theory, Deutsch describes it as a research program that seeks to express all laws of physics in terms of what transformations are possible versus impossible, and it has so far yielded a unified constructor theory of information.

• The core axiom is that the laws of physics can be fully characterized by specifying which physical transformations can be brought about and which cannot.
• Constructor theory is intended to be a level above existing theories (like quantum theory), constraining what the laws of physics can say in the same way that quantum theory constrains what classical dynamical laws can look like.
• The theory emerged from Deutsch’s attempt to extend the theory of quantum computation to include a correspondence between programs and physical systems, and it has been developed primarily in collaboration with Chiara Marletto.

Deutsch keeps a personal list of innovations he initially believed were impossible, which serves as a reminder of the limits of his own foresight.

• Examples include Mathematica (he thought a general-purpose mathematical notation system was impossible), laser guide star adaptive optics (he thought atmospheric correction via laser would not work well), Wikipedia (he expected it would be overrun by spam), and X’s Community Notes (he expected bad actors to game the system).
• Wikipedia initially defied his expectations but has since degraded due to bias and error, confirming his original concern; Community Notes, against his expectations, has worked well so far.
• He includes AGI and natural language conversation on this list, having previously thought them impossible.

His advice to students and researchers is to follow their curiosity and interest in the present rather than making career decisions based on long-term predictions about which fields will become important.

• He warns that the more prophecy required to justify a present choice, the more error-prone that choice will be, since the landscape of ideas will inevitably change.
• He encourages working on what is fun and engaging today, because passion is the most reliable driver of genuine progress, and attempting to leapfrog ahead based on speculative forecasts is dangerous and likely to lead to stagnation.