Pentcho Valev
2023-04-27 23:44:58 UTC
The formula
(frequency) = (speed of light)/(wavelength)
says that decrease of frequency is paired either with decrease of speed or with increase (stretching) of wavelength. The latter alternative has an apocalyptic power - if it is the false one, nothing will remain of modern cosmology, not even of modern physics. And yet the idea that photons can be stretched is not just false - it is preposterous.
"No experiment has ever been performed that verifies that expanding space can indeed alter the wavelength of an already moving photon."
Actually, no observation has ever shown that a length or a distance between any two things has been stretched by space expansion. The wavelength of photons is no exception.
Cosmologists are plagued by (actual or anticipated) questions like:
If the universe is expanding, then why aren't we, why no length has been observed to stretch, why no two things have been observed to move apart pushed by expansion, etc.
In order to alleviate the problem, cosmologists have tweaked the theory. Our theory predicts expansion, cosmologists have decided, only for pure voids (the annoying questions automatically become pointless). For spaces where stretching or moving apart is observable and the annoying questions are relevant, our theory predicts no expansion at all. The universe is expanding, but there are nonexpanding patches:
Sabine Hossenfelder: "The solution of general relativity that describes the expanding universe is a solution on average; it is good only on very large distances. But the solutions that describe galaxies are different - and just don't expand. It's not that galaxies expand unnoticeably, they just don't. The full solution, then, is both stitched together: Expanding space between non-expanding galaxies...It is only somewhere beyond the scales of galaxy clusters that expansion takes over." https://www.forbes.com/sites/startswithabang/2017/07/28/most-things-dont-actually-expand-in-an-expanding-universe/
"Space DOES NOT Expand Everywhere...Is the space inside, say, a galaxy growing but overcome by the gravitational attraction between the stars? The answer is no. Space within any gravitationally bound system is unaffected by the surrounding expansion."
How can stretching occur if part of space is expanding and the other part is not expanding? Light is stretched as it travels in the space between galactic clusters, then stretching stops as the light enters a cluster, then stretching continues as the light leaves the cluster, etc? Idiotic, isn't it?
There is no stretching. The redshift known as "cosmological" (or "Hubble") is due to the speed of light slowing down as photons travel through vacuum, in a non-expanding universe. Accordingly, the cosmic microwave background, CMB, is very, very slow light, very, very highly redshifted, coming from very, very far away.
Pentcho Valev https://twitter.com/pentcho_valev
(frequency) = (speed of light)/(wavelength)
says that decrease of frequency is paired either with decrease of speed or with increase (stretching) of wavelength. The latter alternative has an apocalyptic power - if it is the false one, nothing will remain of modern cosmology, not even of modern physics. And yet the idea that photons can be stretched is not just false - it is preposterous.
"No experiment has ever been performed that verifies that expanding space can indeed alter the wavelength of an already moving photon."
Actually, no observation has ever shown that a length or a distance between any two things has been stretched by space expansion. The wavelength of photons is no exception.
Cosmologists are plagued by (actual or anticipated) questions like:
If the universe is expanding, then why aren't we, why no length has been observed to stretch, why no two things have been observed to move apart pushed by expansion, etc.
In order to alleviate the problem, cosmologists have tweaked the theory. Our theory predicts expansion, cosmologists have decided, only for pure voids (the annoying questions automatically become pointless). For spaces where stretching or moving apart is observable and the annoying questions are relevant, our theory predicts no expansion at all. The universe is expanding, but there are nonexpanding patches:
Sabine Hossenfelder: "The solution of general relativity that describes the expanding universe is a solution on average; it is good only on very large distances. But the solutions that describe galaxies are different - and just don't expand. It's not that galaxies expand unnoticeably, they just don't. The full solution, then, is both stitched together: Expanding space between non-expanding galaxies...It is only somewhere beyond the scales of galaxy clusters that expansion takes over." https://www.forbes.com/sites/startswithabang/2017/07/28/most-things-dont-actually-expand-in-an-expanding-universe/
"Space DOES NOT Expand Everywhere...Is the space inside, say, a galaxy growing but overcome by the gravitational attraction between the stars? The answer is no. Space within any gravitationally bound system is unaffected by the surrounding expansion."
How can stretching occur if part of space is expanding and the other part is not expanding? Light is stretched as it travels in the space between galactic clusters, then stretching stops as the light enters a cluster, then stretching continues as the light leaves the cluster, etc? Idiotic, isn't it?
There is no stretching. The redshift known as "cosmological" (or "Hubble") is due to the speed of light slowing down as photons travel through vacuum, in a non-expanding universe. Accordingly, the cosmic microwave background, CMB, is very, very slow light, very, very highly redshifted, coming from very, very far away.
Pentcho Valev https://twitter.com/pentcho_valev