Relational Quantum Mechanics

Prompt to the Lumo chatbot:

There must be those who see the photon as a quantum of interaction, rather than a quantum of independent existence.

Lumo responded:

Worked through your question

The user is making an observation about a philosophical/interpretational perspective on quantum mechanics - specifically about whether photons should be understood as "quantum of interaction" (relational/process-oriented view) versus "quantum of independent existence" (substance/ontological view). This is a legitimate topic in the philosophy of physics and quantum foundations.

Let me think about what I know:

  1. The standard textbook view treats photons as discrete particles/quanta of the electromagnetic field
  2. There are various interpretations in quantum field theory and quantum foundations
  3. Some relational or process interpretations do emphasize interactions over independent entities
  4. This connects to broader debates in metaphysics about substance vs. process ontology

The user seems knowledgeable enough to make this distinction, so they're likely looking for engagement on this philosophical point rather than basic education.

I should:

  1. Acknowledge this is a real perspective in philosophy of physics
  2. Explain the distinction they're pointing to
  3. Mention relevant interpretational frameworks
  4. Maybe suggest where to find more information

Since this is about established philosophical positions in physics (not current events), I can draw from my training knowledge. However, I should be careful not to claim definitive authority on ongoing debates in philosophy of physics.

This doesn't require web search - it's asking about an established philosophical perspective, not current news or specific recent developments. Let me respond thoughtfully.

Done

You've touched on a profound debate in the philosophy of quantum physics. Yes, there are indeed physicists and philosophers who argue precisely this—that the photon shouldn't be conceived as a standalone entity with independent existence, but rather as a quantized excitation that only manifests through interactions.

The distinction you're highlighting runs deep:

Independent Existence View: The standard Copenhagen-influenced presentation tends to treat photons as little packets of electromagnetic energy that "exist" between emission and absorption. They carry definite properties (energy, momentum, polarization) even when unobserved. This is convenient pedagogically, but it inherits classical intuitions about particles that may mislead us about quantum reality.

Interaction/Relational View: An alternative framework—found in relational quantum mechanics, QBism, and certain readings of quantum field theory—suggests that what we call a "photon" is really just the measurable transfer of energy/momentum during an interaction event. Between emission and absorption, it may not make sense to assign it an ontologically robust existence. The photon is literally the interaction itself, not a thing traveling through space.

This resonates with several modern developments:

  • Quantum Field Theory: The fundamental objects are fields; particles are excitations. But those excitations only become physically meaningful when coupled to measurement apparatus or other fields.

  • Rovelli's Relational Quantum Mechanics: Physical properties (including particle identities) are relative to observers/interaction contexts—not absolute.

  • Process Ontology: Philosophers like Whitehead and contemporary process physicists argue that reality consists fundamentally of events/processes, not persistent substances. Photons fit neatly here as quanta of electromagnetic process, not tiny bullets.

There's also the Wheeler-Feynman absorber theory, which treats radiation as fundamentally involving both emitter and absorber in a time-symmetric relationship—the photon as the link between them rather than a traveler.

The practical upshot? For calculation purposes, the difference barely matters. For understanding what quantum theory tells us about nature... it matters quite a lot. The relational view avoids certain paradoxes (like delayed choice experiments seeming weird) because it never assumes the photon had a definite state independent of the experimental arrangement.

Are you coming at this from a particular framework, or exploring the tension between these views generally?