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There's no point in arguing about this here. There's a very well defined, mathematical theory called General Relativity, which explains gravitational phenomena

There's no point in arguing about this here. There's a very well defined, mathematical theory called General Relativity, which explains gravitational phenomena from Mercury's precession all the way to the expansion of the Universe. If you take the time to learn General Relativity, and to learn how to apply it to cosmology, you will see that there are rigorous mathematical answers to the various questions you're raising. I want to point out that this isn't esoteric stuff that only a few people understand. General Relativity and cosmology are part of a standard undergraduate physics curriculum. It only takes a few years of study, starting from Physics 101, to get to the point where you can derive the answers to all your questions from scratch.

oneshtein 3y ago
How GR explains claimed FTL speed of GLASS-z12? (20Bly travelled in 13By, 1.5c). I'm listening with both ears.
- ben_w 3y ago
  You've already got the answer: space expanded. Spacetime being dynamic is kinda the point of GR. "How" this specific expansion happens is an open question — not because nobody has any idea, but because we can't distinguish between three of them and a forth leads directly to the unsolved challenge of combining GR with quantum mechanics.
  - oneshtein 3y ago
    No, this is not an answer, because it breaks number of laws of physics, such conservation of energy. It looks like an excuse that an answer. It's just heavy stretching of the evidence until it fits the BB model of evolution of Universe. Static Universe model of evolution doesn't requires such stretching: CMB is just light of distant galaxies. End of story.
    - ben_w 3y ago
      > this is not an answer, because it breaks number of laws of physics, such conservation of energy GR doesn't conserve energy. What follows is a bit beyond my level so I may be misremembering, but IIRC Noether's theorem is that conservation laws are always identical to some symmetries, and the symmetry for energy (time?) just isn't true in GR. (I don't think it's even true in SR because space and time are observer dependent, but at least in SR you can get a different conserved quantity because all observers agree on a space-time interval; but as I implied in a different comment where I mentioned brilliant, this is my hobby not my profession).
    - DiogenesKynikos 3y ago
      > CMB is just light of distant galaxies. End of story. The CMB is a perfect blackbody. Galaxies are far from a blackbody. Your explanation fails if one knows even a tiny amount about astronomy. Before you criticize Big Bang cosmology, you should learn the theory. That means studying General Relativity, learning to derive the Friedmann Equations, learning about the (utterly overwhelming) observational evidence for the theory, etc. Then you'll be in a position to ask intelligent questions about the theory. I promise you that if you learn the theory, you'll understand that the questions you're asking either don't make sense or have obvious answers. For example, conservation of energy does not hold in General Relativity. You keep saying that expansion is an ad hoc assumption that breaks physical laws. However, if you solve the Einstein Field Equations, you'll see that the universe must be either expanding or contracting. This fact bothered Einstein so much that he tried to modify General Relativity to get rid of it, something he regretted when observational evidence firmly established that the universe was indeed expanding. This was all the way back in the 1920s, and the evidence is so overwhelming now, a full century later, that it's impossible to deny.
      - oneshtein 3y ago
        > The CMB is a perfect blackbody. Galaxies are far from a blackbody. CMB is not emitted by a single galaxy or even group of galaxies. It's light of trillions of supeclusters, like our Visible Universe, averaged. I expect that almost any local unevenness should be polished out when averaged over such large area and distance. We are not seeing stream of photons from individual emitters, we see random photons from extremely huge range of emitters at extremely huge range from us. If clump together all radiation from all our Visible Universe into single stream of photons, then we will see something very similar. > For example, conservation of energy does not hold in General Relativity. Then something is wrong.
ben_w 3y ago
Doesn't even need that much — their questions so far are at my level, and I keep messing up the much simpler special relatively questions on brilliant.org

oneshtein 3y ago

How GR explains claimed FTL speed of GLASS-z12? (20Bly travelled in 13By, 1.5c). I'm listening with both ears.

ben_w 3y ago
You've already got the answer: space expanded. Spacetime being dynamic is kinda the point of GR. "How" this specific expansion happens is an open question — not because nobody has any idea, but because we can't distinguish between three of them and a forth leads directly to the unsolved challenge of combining GR with quantum mechanics.
- oneshtein 3y ago
  No, this is not an answer, because it breaks number of laws of physics, such conservation of energy. It looks like an excuse that an answer. It's just heavy stretching of the evidence until it fits the BB model of evolution of Universe. Static Universe model of evolution doesn't requires such stretching: CMB is just light of distant galaxies. End of story.
  - ben_w 3y ago
    > this is not an answer, because it breaks number of laws of physics, such conservation of energy GR doesn't conserve energy. What follows is a bit beyond my level so I may be misremembering, but IIRC Noether's theorem is that conservation laws are always identical to some symmetries, and the symmetry for energy (time?) just isn't true in GR. (I don't think it's even true in SR because space and time are observer dependent, but at least in SR you can get a different conserved quantity because all observers agree on a space-time interval; but as I implied in a different comment where I mentioned brilliant, this is my hobby not my profession).
  - DiogenesKynikos 3y ago
    > CMB is just light of distant galaxies. End of story. The CMB is a perfect blackbody. Galaxies are far from a blackbody. Your explanation fails if one knows even a tiny amount about astronomy. Before you criticize Big Bang cosmology, you should learn the theory. That means studying General Relativity, learning to derive the Friedmann Equations, learning about the (utterly overwhelming) observational evidence for the theory, etc. Then you'll be in a position to ask intelligent questions about the theory. I promise you that if you learn the theory, you'll understand that the questions you're asking either don't make sense or have obvious answers. For example, conservation of energy does not hold in General Relativity. You keep saying that expansion is an ad hoc assumption that breaks physical laws. However, if you solve the Einstein Field Equations, you'll see that the universe must be either expanding or contracting. This fact bothered Einstein so much that he tried to modify General Relativity to get rid of it, something he regretted when observational evidence firmly established that the universe was indeed expanding. This was all the way back in the 1920s, and the evidence is so overwhelming now, a full century later, that it's impossible to deny.
    - oneshtein 3y ago
      > The CMB is a perfect blackbody. Galaxies are far from a blackbody. CMB is not emitted by a single galaxy or even group of galaxies. It's light of trillions of supeclusters, like our Visible Universe, averaged. I expect that almost any local unevenness should be polished out when averaged over such large area and distance. We are not seeing stream of photons from individual emitters, we see random photons from extremely huge range of emitters at extremely huge range from us. If clump together all radiation from all our Visible Universe into single stream of photons, then we will see something very similar. > For example, conservation of energy does not hold in General Relativity. Then something is wrong.

ben_w 3y ago

Doesn't even need that much — their questions so far are at my level, and I keep messing up the much simpler special relatively questions on brilliant.org