The inception of quantum mechanics is often traced to the summer of 1925, specifically to the treeless island of Helgoland. It was there that a young Werner Heisenberg laid the groundwork for what would become a remarkably successful framework for understanding reality. At the core of his proposal was a deliberate focus on quantifiable outcomes derived from particle measurements, eschewing abstract theoretical constructs.
This approach, while brilliant, has presented physicists with persistent challenges for a century. A significant portion of these difficulties stems from ambiguity surrounding the definition of an “observer” and the precise nature of an “observation.” This has led to debates about whether reality itself is contingent on being perceived.
It is time, I believe, to move beyond this conceptual entanglement. My extensive engagement with quantum theory has led me to conclude that the concept of observers is unnecessary and, in fact, fundamentally flawed. I advocate for a more coherent and logical description of the quantum realm, supported by experimental evidence. This alternative perspective challenges fundamental assumptions, suggesting that neither observers nor particles, as we conventionally understand them, truly exist. Even space and time warrant re-examination.
While this conceptual shift delves into unfamiliar territory, its pursuit offers profound insights, potentially revealing avenues beyond our current understanding of quantum theory. To begin this exploration, a brief overview of modern physics and its inherent complexities is in order.
The Observer in Physics: From Relativity to Quantum Theory
The notion of an observer has long been integral to physics, predating quantum mechanics. Albert Einstein’s theories of special and general relativity, for instance, relied heavily on the concept. General relativity posits a unified fabric of space-time, where gravity arises from its curvature. This theory implies that observers in regions with varying space-time curvature would experience time at different relative rates.
In instructional contexts regarding relativity, observers are often conceptualized as individuals. However, the time experienced by any moving object, even an atom, changes relative to objects in different gravitational fields. These temporal variations do not necessitate explicit recording by a conscious observer, thus rendering a distinct category of “observers” superfluous.
General relativity represents one of the two foundational pillars of modern physics, the other being quantum theory. Quantum theory’s essence lies in the discreteness of reality at its most fundamental level. For instance, atomic energy exchanges occur in quantized packets rather than continuously. Within quantum theory itself, observers are embedded, distinguishing between particles before and after “observation.” Prior to observation, particles are described by a wave function, an equation encapsulating a spectrum of potential properties—a superposition. Upon observation, this wave function is said to “collapse” into a definite value.
This collapse mechanism engenders numerous questions, most notably regarding its initiation and underlying cause. It also leads to paradoxes, such as Eugene Wigner’s “friend” thought experiment. Wigner envisioned a friend within a sealed laboratory performing a quantum measurement while he waited outside. The discrepancy arises when comparing their descriptions of reality: Wigner, having made no direct observation, describes the entire laboratory as governed by the diffuse wave function, while his friend perceives a concrete outcome. Wigner’s paradox probed the point at which an observation becomes definitive.
Entanglement as the Core of Observation
While some physicists propose modifications to quantum theory to address these issues, my view differs. To elaborate, it is crucial to understand entanglement, which Erwin Schrödinger identified as quantum theory’s defining characteristic. Quantum entanglement, often perceived as enigmatic, is fundamentally a linkage between quantum objects, enabling immediate knowledge of one’s properties upon measuring the other.
The critical insight here is that when we refer to “observations,” we are, in my estimation, describing the moment two systems become entangled. While the system that becomes entangled can indeed be a person—an “observer”—this is not a requisite condition. Consider a classic experiment where a photon in superposition passes through two slits simultaneously, creating an interference pattern. However, if an attempt is made to determine which slit the photon traversed, the interference pattern vanishes. Before attributing this solely to the “collapse” of superposition by observation, it’s important to note that if any other entity is entangled with the photon in a way that reveals its path, the same outcome occurs.
Therefore, the focus should shift from discussing “observers” to discussing entanglement. This perspective effectively resolves Wigner’s paradox, as there is no ultimate observer. Instead, what occurs is the entanglement of the system with the observer, who is merely another system. Quantum theory, in my view, already contains the necessary elements for comprehending reality; we simply need to embrace its full, albeit unconventional, implications.
The Unreality of Particles: A Field-Centric View
To truly grasp this new framework, we must first address the concept of fields, entities that pervade space and evolve over time, a concept pioneered by Michael Faraday. In classical electromagnetism, field values are represented by ordinary numerical quantities (c-numbers). Quantum theory, however, introduces quantum fields, where each point in space is described not by single numbers but by tables of numbers, termed quantum numbers or q-numbers. This shift, first proposed by Heisenberg in 1925, elevates particle positions and momenta to q-numbers, a distinction fundamental to quantum physics.
The complete implications of quantum fields are not universally accepted. When the classical electromagnetic field was quantized, it allowed for more oscillation modes than previously possible. In quantum field theory, there are four such modes, and the theory predicts the field can manifest as particles, such as photons, in each. Curiously, only two of these modes are ever detected; the other two, termed “ghost” photons, are unobservable yet theoretically indispensable.
While this may seem philosophically unsettling, it mirrors many scientific principles where theoretical constructs are posited for their explanatory power. My colleague Chiara Marletto and I suggest that these ghost photons, though undetectable directly, can become entangled with electrons under specific conditions, a form of entanglement that could, in principle, be detected. A 2023 paper outlines an experiment where an electron in superposition would, if our hypothesis is correct, become entangled with these ghosts, a phenomenon amenable to careful measurement—akin to detecting a ghost.
Should this experiment confirm the entanglement of ghost photons, it would underscore that the fundamental entangleable entities are q-numbers, not our human conception of “particles.” Particles merely possess q-numbers, which has led to the misconception that particles are the foundational elements of reality.
Further reinforcing the argument against the fundamental reality of particles is the concept of self-entanglement. In conventional quantum theory, a particle before measurement exists in a superposition of states, occupying multiple positions. From a q-number perspective, these distinct q-numbers representing these positions can become entangled with each other, describing a particle “entangled with itself.”
Over 15 years ago, I proposed an experiment, with my colleague Jacob Dunningham, to test this. The proposal involves creating a delocalized state for a single particle, placing it in a superposition of two locations. Experimental verification of this superposition’s entanglement relies on separate measurements at each location, checking for violations of Bell’s inequality, a signature of entanglement.
Evidence for single-particle entanglement already exists. Experiments by Björn Hessmo and colleagues in 2004 demonstrated that individual photons, spatially split, do violate Bell’s inequality. This suggests that photons themselves are not fundamental, but their associated q-numbers are paramount. While experiments with massive particles like electrons remain challenging, the underlying principle—that q-numbers are fundamental—is expected to hold true.
The Non-Existence of Space and Time
This leads to the question of space and time. While some view their reconciliation with quantum theory and general relativity (quantum gravity) as the ultimate frontier, my perspective is more radical: space and time do not exist as physical entities. Like “observers,” they are convenient descriptive tools—bookkeeping mechanisms—without corresponding physical reality.
Consequently, quantizing gravity does not involve quantizing space-time itself. Instead, it entails quantizing the gravitational field, transforming Einstein’s c-numbers into q-numbers, analogous to the quantization of other fields. This might seem a subtle distinction, given that general relativity equates the gravitational field with the curvature of space-time. However, in this refined view, it is not space or time that bends, but rather fields, such as the electromagnetic field, which binds matter together. Atoms, molecules, clocks, and rulers are all governed by electromagnetism, and the gravitational field’s role is to interact with these fields, dictating their behavior.
The notion of fields existing across an invisible grid we call space-time is a useful conceptualization, but it should not be mistaken for fundamental reality. While some colleagues may find this view extreme, and direct experimental verification is currently challenging, it represents a consistent application of taking quantum theory at face value, treating gravity as any other quantum field.
Therefore, the fundamental constituents of nature, in this framework, are not particles, space, or time, but q-numbers. This perspective offers potential pathways to new insights.
Q-Numbers All the Way Down: A Deeper Quantization
Interactions between quantum fields are mathematically described by the quantum Hamiltonian. A long-standing concern is the mixing of q-numbers with ordinary c-numbers, such as physical constants like the speed of light or electron charge, within these Hamiltonians. While routine, this hybrid nature seems incongruous. The historical process involved quantizing classical equations, but a more elegant approach would be equations that are entirely quantum.
Physicist David Deutsch proposed in the 1980s the elimination of c-numbers entirely, rendering all quantities within quantum Hamiltonians as q-numbers. This profound shift, however, carries significant implications. For instance, if the speed of light, currently a c-number, were transformed into a q-number (representing a point in a quantum field), it would imply the existence of a novel quantum field associated with the speed of light. This parallels the emergence of “ghost” photons upon the quantization of the electromagnetic field, suggesting a reality more complex than initially perceived.
This concept is experimentally testable. The existence of additional quantum fields would allow particles to become entangled with them. For example, in a maximally entangled atom-photon system, an intermediary field would create a three-body entangled system, weakening the entanglement between the atom and photon. Jim Franson proposed a detection method in 2022, conceptually similar to the ghost photon experiment, which is technologically feasible.
The process of quantization could potentially extend to deeper levels. Q-numbers are tables of numbers; these numbers themselves could be upgraded to q-numbers, leading to tables of tables of tables. In this view, the fundamental structure is not a stacked hierarchy of turtles, but an infinite regression of q-numbers.
While philosophers may object to infinite regress, nature is not bound by such scruples. The universe may indeed be a boundless expanse, continuously revealing new mysteries to physicists.