Journal of Physics G: Nuclear and Particle Physics, ACCEPTED MANUSCRIPT: Light speed variation from GRB 221009A, Jie Zhu and Bo-Qiang Ma https://iopscience.iop.org/article/10.1088/1361-6471/accebb/pdf
"It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed, and a series of previous researches on high-energy photon events from gamma-ray bursts (GRBs) and active galactic nuclei (AGNs) suggest a light speed variation v(E)=c(1−E/ELV) with ELV=3.6×1017 GeV...This result suggests a scenario that high-energy photons travel slower than low-energy photons...This remarkable coincidence between the highest energy photon event observed by Fermi-LAT during the prompt phase and the sharp spike in the low energy light curves of brightest gamma ray burst GRB 221009A supports the light speed variation suggested in previous studies." Light speed variation from GRB 221009A, Jie Zhu , Bo-Qiang Ma https://arxiv.org/pdf/2210.11376.pdf
Again:
"It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers."
This is OBVIOUSLY false. Assume that a light source emits equidistant pulses and an observer starts moving towards the source:
View: https://youtube.com/watch?v=bg7O4rtlwEE
The speed of the light pulses relative to the stationary observer is
c = df
where d is the distance between subsequent pulses and f is the frequency at the stationary observer. The speed of the pulses relative to the moving observer is
c'= df' > c
where f' > f is the frequency at the moving observer.
That is, the speed of light relative to the observer VARIES with the speed of the observer.
"It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed, and a series of previous researches on high-energy photon events from gamma-ray bursts (GRBs) and active galactic nuclei (AGNs) suggest a light speed variation v(E)=c(1−E/ELV) with ELV=3.6×1017 GeV...This result suggests a scenario that high-energy photons travel slower than low-energy photons...This remarkable coincidence between the highest energy photon event observed by Fermi-LAT during the prompt phase and the sharp spike in the low energy light curves of brightest gamma ray burst GRB 221009A supports the light speed variation suggested in previous studies." Light speed variation from GRB 221009A, Jie Zhu , Bo-Qiang Ma https://arxiv.org/pdf/2210.11376.pdf
Again:
"It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers."
This is OBVIOUSLY false. Assume that a light source emits equidistant pulses and an observer starts moving towards the source:
The speed of the light pulses relative to the stationary observer is
c = df
where d is the distance between subsequent pulses and f is the frequency at the stationary observer. The speed of the pulses relative to the moving observer is
c'= df' > c
where f' > f is the frequency at the moving observer.
That is, the speed of light relative to the observer VARIES with the speed of the observer.