Gravity and Quantum Mechanics: Can Gravity Collapse the Wave Function? A New Scientist Interview on Quantum Gravity

In this New Scientist interview, Yvette explains why simply quantizing spacetime may be misguided and argues that gravity should be treated as fundamental while quantum mechanics is modified to accommodate it. The conversation surveys Penrose's gravity induced collapse idea, the Many-Worlds interpretation, and the philosophical implications of a single versus multiple universes. It then moves to concrete experimental directions, including Bose-Einstein condensates (BECs) and interferometry as tools to probe how gravity affects quantum states and to test gravity related ideas at scales where quantum effects and spacetime curvature intersect. The discussion also touches gravitational waves, dark matter and dark energy as potential windows into quantum gravity.

• Gravity as a potential driver of wave function collapse
• Two routes to unification: modify gravity or modify quantum mechanics
• BECs and interferometry as test beds for gravity mediated quantum effects
• Distinguishing gravity induced collapse from many worlds through experiments

Introduction

The interview frames a core question in fundamental physics: how do we reconcile quantum theory with general relativity? The speaker argues that trying to quantize spacetime itself may be the wrong path and that gravity should be placed at the center of the unification effort, with quantum mechanics adapted around it.

The Core Problem

Time is treated differently in the two theories: quantum mechanics uses a single time parameter, while general relativity makes time a relative quantity dependent on the observer and the gravitational field. When a mass is placed into a quantum superposition across two locations, clocks at different points in spacetime may tick at different rates, creating a tension with the Schrödinger equation that presumes a single time. The discussion moves to the measurement problem and why the wave function collapse is not yet understood.

Paths to Unification

The dialogue explores Roger Penrose's idea that gravity could play a role in wave function collapse, contrasting two broad avenues: modifying gravity to fit quantum mechanics or modifying quantum mechanics to align with gravity. The speaker favors gravitating quantum theory, arguing that quantum mechanics already poses deep puzzles such as the nature of the quantum state and the origin of probabilities, and that gravity could help explain collapse without discarding the quantum framework altogether.

Interpretations and Tests

The debate engages with Many-Worlds versus gravity induced collapse, noting how philosophical stances about a single versus multiple universes influence physical theory choices. The possibility that gravity might collapse superpositions in large enough systems is highlighted as a falsifiable prediction that could challenge the universality of quantum mechanics.

Experimental Frontiers

The conversation turns to experimental strategies, stressing that test beds such as Bose-Einstein condensates and atom interferometry could illuminate the interface between gravity and quantum mechanics. The potential to probe high frequency gravitational waves and to search for deviations from standard gravity is discussed, along with the practical challenges of creating and maintaining large quantum superpositions in ultra cold gases.

Bose-Einstein Condensates and Gravity

BECs are presented as an attractive platform because the atoms in a condensate can occupy the same quantum state, becoming highly delocalized and exquisitely sensitive to spacetime distortions. The discussion covers the benefits of cooling to nano Kelvin temperatures, the coherence requirements, and the difficulty of scaling up to masses large enough to reveal gravitationally induced collapse.

Consciousness, Mind and Matter

Penrose's provocative link between gravity, quantum mechanics and consciousness is examined, along with the current state of dualist versus materialist interpretations and how advances in artificial intelligence may intensify these questions. The speaker also reflects on a personal shift toward a model where mind and matter are both fundamental and interact, while acknowledging this stance could evolve.

Outlook

The interview closes with optimism about the potential for experiments to probe the quantum gravity boundary and to help determine whether gravity collapses the wave function, or whether many worlds remains a viable description of reality. The speaker emphasizes the experimental ethos motivating her work: theory must be testable and testable experiments drive progress toward a deeper understanding of the universe.