Re-evaluating the Mass Status of Photons in the Context of Particle Definition: Dynamic Particle with Negative Apparent Mass.

Soumendra Nath Thakur 

April 18, 2025

The commonly cited statement—“The photon has no mass, but it is a particle”—raises a fundamental inconsistency when examined through the lens of foundational physical principles.

In the broader framework of physical sciences, the designation of any entity as a “particle” traditionally presumes the presence of either a "real mass" or an "effective mass". Absent such a characteristic, the term “particle” becomes physically ambiguous. This is particularly relevant in advanced frameworks like Extended Classical Mechanics (ECM), which seeks to reconcile and extend classical and relativistic insights.

ECM introduces the concept of negative apparent mass (−Mᵃᵖᵖ), a form of effective mass that corresponds to kinetic energy, particularly in massless or near-massless regimes. Under this interpretation, photons—entities which exhibit kinetic behaviour—are understood to possess dynamic effective mass, even in the absence of rest mass.

Additionally, it is important to distinguish between "rest energy"—associated with "rest mass"—and kinetic energy (KE). which does not equate to rest energy under the relativistic mass-energy relation. This distinction has significant implications for the interpretation of photon behaviour and classification.

Therefore, within the ECM framework, the photon is more accurately described as a dynamic particle with negative apparent mass. This terminology reflects both its energy-based behaviour and its mass-related characteristics in motion.

If a photon were to lose its dynamism (i.e., kinetic expression), it would simultaneously lose the characteristics that define its particle-like behaviour, leading to a loss of existence in that form.

Finally, the term “massless particle,” while common in conventional discourse, may be considered incomplete. A more accurate description would treat the photon's effective mass as less than zero (<0) rather than strictly zero. This nuanced reinterpretation allows for a consistent and complete understanding of the photon's physical nature.