Probing the Speed of Light with Radio Waves at Extremely Low Frequencies
Abstract
The speed of light, a fundamental physical constant and thought to be independent of frequency, is tested here with naturally occurring radio waves in the atmosphere at extremely low frequencies. It is shown that the speed of light in the frequency range 5 50Hz is known with an accuracy determined by perturbations of the ionospheric reflection height associated with space weather phenomena, which place an upper limit on the photon rest mass mγ≲4×10-52 kg to date.
- Publication:
-
Physical Review Letters
- Pub Date:
- July 2004
- DOI:
- Bibcode:
- 2004PhRvL..93d3901F
- Keywords:
-
- 41.20.Jb;
- 92.60.Ta;
- 94.20.Ee;
- Electromagnetic wave propagation;
- radiowave propagation;
- Electromagnetic wave propagation