Portals to a New Reality: Quantum Numbers, Entanglement and the Quest to Quantize Gravity

In this interview, physicist Flatko challenges the traditional view that particles, space, and time are fundamental. He argues that quantum numbers underpin reality, that observers are not special in quantum mechanics, and that entanglement can replace the concept of observation. The discussion covers why general relativity and quantum mechanics remain separate, the role of Schrödinger's cat and Wigner’s friend, and bold experimental proposals to probe gravity at the quantum level. The talk points toward a possible future where gravity is treated as a quantum field and where space and time may emerge from a deeper quantum reality.

Introduction and the Problem of Dual Theories

The conversation opens with a provocative stance: the apparent contradictions between general relativity and quantum mechanics stem from a wrong view of reality that presumes a classical world exists out there. The guest, Flatko, argues that ultimate reality is encoded in cue numbers or quantum numbers rather than in the existence of atoms, and that even time and space may be emergent from a deeper quantum substrate. This sets the stage for a broader critique of how physics has approached observers, particles, space, and time.

The Two Pillars of Modern Physics

The discussion revisits General Relativity as a classical, continuous description of spacetime and Quantum Mechanics as a theory built on discrete quantum events. Both theories have been validated by experiments, yet they operate in largely disjoint domains. Observers are treated as separate from the systems they observe, a stance that Flatko questions, proposing instead a unified quantum treatment of all physical systems, including experimental apparatus and even humans.

Rethinking Observers and Measurement

A central theme is the misframing of the observer in quantum theory. Flatko argues that any physical system can function as an observer, and that many classic paradoxes, such as Schrödinger's cat or Wigner’s friend, dissolve when everything in the universe is treated quantum mechanically. The idea is to replace the problematic notion of a special observer with a universal quantum description in which entanglement ties the observed and the observer together across branches of the wave function.

Entanglement as the Core Mechanism

Entanglement is presented as the mechanism by which definite outcomes emerge in individual branches of reality without invoking a mysterious collapse. The original Schrödinger paradox is revisited: a quantum event can entangle with macroscopic systems, leading to correlated outcomes that differ depending on the branch. This leads to a triad of perspectives: the inside observer who records a definite result, the outside observer who sees a superposition, and the external perspective that must reconcile both states via entanglement.

Bell Inequalities and Experimental Pathways

To test the non-classical nature of reality, the talk highlights Bell inequalities and the possibility of performing entanglement tests with larger, more complex systems such as atoms in spatial superpositions. Violations of Bell-type inequalities would rule out hidden variable interpretations and underscore the reality of quantum correlations between spatially separated branches. While photon experiments have demonstrated these effects, extending them to massive particles like atoms remains an ongoing, technically challenging frontier.

Quantum Numbers and the Nature of Particles

Flatko reframes particles as emergent from quantum numbers rather than fundamental building blocks. He asserts that particles, including bits of matter, can be created and destroyed only within the quantum numbers that describe their states. This perspective dovetails with relativity, since energy and mass can transform into one another, a process already accommodated by quantum theory, suggesting a deeper, invariant layer of reality encoded by cue numbers.

Space and Time Reconsidered

The dialogue challenges the traditional view of space and time as fundamental local quantities. Space-time, according to Flatko, may be a convenient classical scaffold, while the true dynamical content resides in quantum fields and the quantum numbers that undergird them. This stance aligns with a broader research program that seeks to quantize gravity by treating gravitational degrees of freedom as quantum operators, rather than quantizing spacetime itself in the classical sense.

Towards a Quantized Gravity Framework

A key proposal is to quantize gravity in a manner analogous to how electromagnetism is quantized: by upgrading the fields that mediate gravity to quantum operators while retaining a classical spacetime as an emergent description for practical purposes. In this view, the speed of light and other constants could themselves be subject to a quantum description, with extra quantum systems potentially mediating their interactions. The aim is to test whether gravity must be quantum mechanical at accessible energy scales, rather than assuming it is purely classical.

Possible Lab Experiments

Several concrete experiments are proposed. One involves placing two massive objects in spatial superpositions and observing whether gravity can generate entanglement between them. If a gravitationally mediated entanglement is observed, it would imply that gravity is a quantum entity. Other ideas explore how quantized gravitational components would affect entanglement monogamy and whether indirect evidence could reveal a third, previously unquantized system influencing gravity. Condensates and cold-atom systems offer promising platforms for these tests in the near term, with the expectation that such momentum could shift the entire research program toward a quantum description of gravity in the laboratory.

Speculations on Time and Speed of Light

The discussion also touches on the possibility of quantizing time itself or treating the speed of light as a quantum variable. If time, or fundamental constants, were subject to quantum fluctuations, new experimental signatures could emerge in measurements of time dilation or light propagation, pushing the boundaries of how we model the interaction between quantum theory and relativity. Time, much like space, is treated as a pedagogical tool in some current theories, and quantizing it would demand a radical rethinking of measurement, synchronization, and causality.

A Ten-Year Horizon and Beyond

Looking ahead, Flatko imagines a research ecosystem where the proposed tests yield results that compel a rethinking of general relativity as a limiting case of a broader quantum theory. If successful, these experiments could reveal that classical numbers in Einstein's equations must be upgraded to quantum numbers, guiding physicists toward a unified framework. The ultimate aim is to uncover a deeper, testable theory in which quantum mechanics and gravity are two faces of a single underlying reality, with space and time emerging from a quantum substrate rather than dictating the structure of physical law.

Conclusion

The dialogue leaves readers with a sense of a field at a crossroads, where radical ideas about quantum numbers, entanglement, observers, and gravity could reshape our understanding of reality. The proposals bridge philosophy and empirical science, offering a path toward a more coherent picture of the universe that preserves the predictive power of current theories while expanding the ontological foundation upon which they rest.