Astronomical time-of-flight photon speedometer

Area of Science:

• Astrophysics and Cosmology
• Experimental Physics

Background:

• Measuring the velocity of photons from faint extragalactic sources is challenging.
• Previous studies have relied on indirect methods or less precise measurements.

Purpose of the Study:

• To develop and utilize a novel dual-band, fiber-optic, photon time-of-flight instrument.
• To perform the first direct photon group velocity measurements for extragalactic objects.
• To test the invariance of photon group velocity across cosmic distances and validate cosmological models.

Main Methods:

• Development of a specialized fiber-optic instrument for photon time-of-flight measurements.
• Optimization for detecting visible photons from dim astronomical sources (apparent magnitude m>12).
• Measurement of photon group velocity for objects with redshifts ranging from 0 to 1.33.

Main Results:

• The photon group velocity was measured to be 3.00±0.03×10^8 m/s.
• The measured velocity was found to be invariant within experimental error across the observed redshift range (0≤z≤1.33).
• The results provide direct experimental evidence for the constancy of light speed in extragalactic space.

Conclusions:

• The findings validate Einstein's theory of general relativity.
• The results are consistent with the Friedmann-Lemaître-Robertson-Walker and hyperbolic anti-de Sitter cosmological models.
• The data exclude the elliptical de Sitter metric, providing constraints on cosmological parameters.