Richard Feynman: "I want to emphasize that light comes in this form - particles. It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you probably learned something about light behaving like waves. I'm telling you the way it does behave - like particles. You might say that it's just the photomultiplier that detects light as particles, but no, every instrument that has been designed to be sensitive enough to detect weak light has always ended up discovering the same thing: light is made of particles." https://www.amazon.com/QED-Strange-Theory-Light-Matter/dp/0691024170

If Feynman is correct, any wave-based concept of variation of the wavelength of light (e.g. https://www.youtube.com/watch?v=3mJTRXCMU6o&t=77s) is unrealistic. It makes sense to advance the following

Axiom: The wavelength of light is invariable.

and examine the logical consequences. First of all, given the formula (frequency)=(speed of light)/(wavelength), we conclude:

Any frequency shift entails (is caused by) a proportional speed-of-light shift.

It follows that the cosmological (Hubble) redshift is due to light gradually slowing down as it travels through intergalactic space, in a non-expanding universe. The idea that vacuum slows down light has been largely discussed but only in terms of quantum gravity. The implication that the Hubble redshift might be due to speed of light decrease is persistently ignored:

"...in some quantum-gravity models, the speed of photons in gamma rays would be affected by the grainy nature of spacetime..." https://fqxi.org/community/articles/display/255

Sabine Hossenfelder: "It's an old story: Quantum fluctuations of space-time might change the travel-time of light. Light of higher frequencies would be a little faster than that of lower frequencies. Or slower, depending on the sign of an unknown constant. Either way, the spectral colors of light would run apart, or 'disperse' as they say if they don't want you to understand what they say. Such quantum gravitational effects are miniscule, but added up over long distances they can become observable. Gamma ray bursts are therefore ideal to search for evidence of such an energy-dependent speed of light." http://backreaction.blogspot.fr/2017/01/what-burst-fresh-attempt-to-see-space.html

"Some physicists, however, suggest that there might be one other cosmic factor that could influence the speed of light: quantum vacuum fluctuation. This theory holds that so-called empty spaces in the Universe aren't actually empty - they're teeming with particles that are just constantly changing from existent to non-existent states. Quantum fluctuations, therefore, could slow down the speed of light." https://www.sciencealert.com/how-much-do-we-really-know-about-the-speed-of-light

For not so distant stars slow speed of light is manifested as cosmological (Hubble) redshift.

Light from very distant stars (very slow light) is manifested as what is called Cosmic Microwave Background (CMB). (I used to regard CMB as coming from nearby vacuum fluctuations, but that was a wrong idea).

Beyond a certain distance, the star light does not reach us at all.

The invisible "very slow light" and the light that does not reach us explain the Olbers' paradox.

See more here: https://twitter.com/pentcho_valev

Pentcho Valev

Le samedi 3 septembre 2022 à 20:32:37 UTC+2, Pentcho Valev a écrit :

> Beyond a certain distance, the star light does not reach us at all.

> Pentcho Valev

Je suis absolument d'accord avec ça.

Je le répète en boucle (tant pis si ça fait rire les imbécile), la vitesse de la lumière est instantanée dans l'espace-temps réel.

La lumière n'est rien d'autre qu'une interaction électromagnétique instantané dans le référentiel du RECEPTEUR.

Si les galaxies sont très lointaines il est possible que la transmissions deviennent impossible (plus d'interaction).

C'est une explication.

Une autre explication est que plus je m'éloigne, plus la probabilité de recevoir un photon est faible et devient nulle.

En cm², je reçois bien plus de photons du soleil que d'Antarès.

Admetttons un soleil situé à 54 milliards d'années lumière dans une galaxie du fond du ciel.

Statistiquement, je recevrais, si c'est possible, un photon tous les cent mille ans. Ce soleil est indétectable. Le ciel est noir.

"The CMB is a perfect example of redshift. Originally, CMB photons had much shorter wavelengths with high associated energy, corresponding to a temperature of about 3,000 K (nearly 5,000° F). As the universe expanded, the light was stretched into longer and less energetic wavelengths. By the time the light reaches us, 14 billion years later, we observe it as low-energy microwaves at a frigid 2.7 K (-450° F). This is why CMB is so cold now." https://www.universeadventure.org/big_bang/cmb-origins.htm

No. The wavelength of light is invariable. Frequency and speed vary proportionally, in accordance with the formula

(frequency) = (speed of light)/(wavelength)

The so called CMB is extremely cold because the speed of its photons is extremely slow.

More here: https://twitter.com/pentcho_valev

Pentcho Valev