[Paper Review] Does the velocity of light depend on the source movement?

Luis Bilbao|arXiv (Cornell University)|Jun 10, 2016

Orbital Angular Momentum in Optics1 references3 citations

TL;DR

This paper proposes that the speed of light depends on the velocity of its source, challenging Einstein's second postulate of special relativity. By relating light speed and Doppler shift to the source's velocity at the time of detection (not emission), the model quantitatively explains spacecraft tracking anomalies—such as the 1998 NEAR flyby range discrepancy and Doppler residuals—using a modified relativistic theory (VRT) compatible with known electromagnetic phenomena.

ABSTRACT

Data from spacecrafts tracking exhibit many anomalies that suggest the dependence of the speed of electromagnetic radiation with the motion of its source. This dependence is different from that predicted from emission theories that long ago have been demonstrated to be wrong. By relating the velocity of light and the corresponding Doppler effect with the velocity of the source at the time of detection, instead of the time of emission, it is possible to explain quantitatively and qualitatively the spacecraft anomalies. Also, a formulation of electromagnetism compatible with this conception is possible (and also compatible with the known electromagnetic phenomena). Under this theory the influence of the velocity of the source in the speed of light is somewhat subtle in many practical situations and probably went unnoticed in other phenomena.

Motivation & Objective

• To investigate whether experimental evidence contradicts the standard assumption that light speed is independent of the source's motion.
• To resolve persistent anomalies in spacecraft tracking—such as the NEAR flyby range discrepancy and Doppler residuals—by reinterpreting light propagation.
• To develop a viable electromagnetic theory (VRT) that incorporates source velocity effects while remaining consistent with known EM phenomena.
• To test whether the observed anomalies in deep-space tracking data can be explained by a modified light-speed model without invoking new physics or measurement errors.

Proposed method

• Analyzes range disagreement data from the 1998 NEAR flyby between DSN and SSN radar stations, fitting the time-varying range difference to the equation δR(t) = -[R(t)·v(t)]/c.
• Applies a velocity-dependent relativistic theory (VRT) where light speed is c + (v·R̂)/c at detection, differing from standard relativity.
• Uses orbital data and simulated Doppler signals to compare VRT predictions with observed flyby anomalies, adjusting for non-uniform antenna motion and switching times.
• Derives a modified Doppler formula (equation 14) that includes source and receiver velocities at emission and reception times, enabling direct comparison with SRT.
• Adjusts orbital parameters under VRT to remove first-order residuals, showing only a slight rotation of the orbital plane compared to SRT.
• Validates the model by reproducing the phase-shifted, sinusoidal Doppler residuals observed in flyby data, matching reported plots in shape and amplitude.

Experimental results

Research questions

• RQ1 Can the 1 km range discrepancy observed during the 1998 NEAR flyby be explained by a velocity-dependent light speed model?
• RQ2 Why do Doppler residuals in spacecraft tracking exhibit non-random, first-order patterns in v/c, inconsistent with standard relativity?
• RQ3 Is it possible to construct a consistent electromagnetic theory that incorporates source velocity effects on light speed while preserving known EM phenomena?
• RQ4 Why have such velocity-dependent light speed effects not been detected in prior experiments, despite their potential presence?
• RQ5 How does the proposed VRT model differ from naive ballistic theories and why is it experimentally indistinguishable from SRT in most contexts?

Key findings

• The range disagreement between DSN and SSN during the NEAR flyby (up to 1 km) is quantitatively fitted by δR(t) = -[R(t)·v(t)]/c, with p < 10⁻³ significance.
• The model implies that DSN signals propagate at c + (v·R̂)/c in the radar frame, contradicting the second postulate of special relativity.
• The flyby Doppler residuals—previously unexplained—show a clean sinusoidal signature with phase shifts matching VRT predictions, including amplitude and minima/maxima positions.
• Simulated residuals under VRT closely reproduce observed data, with post-encounter and pre-encounter fits showing asymmetric residuals due to antenna switching times.
• The only difference between SRT and VRT orbits is a slight rotation of the orbital plane, indicating minimal conflict with standard ephemerides.
• The theory remains experimentally indistinguishable from SRT in most contexts, explaining why such effects have not been detected earlier despite their presence in deep-space tracking anomalies.