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Originally Posted by Fortis
In your approach does matter move along geodesics in spacetime, and light along null-geodesics?
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Of course they do. "No attractive forces between particles" means just this.
Quote:
Originally Posted by Fortis
Actually the classic FRW model is pure GR.
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"Pure GR" doesn't need an assumption that the universe is expanding since it works even better also without this additional assumption. For the time being I don't know about any observation that requires this assumption. For over 20 years I'm asking for a proof that the universe is expanding and there is none. There are only guesses not very consistent whith the rest of physics. Adding the assumption that the universe is expanding created the whole new picture of nature (a.k.a. "Big Bang cosmology") which still has problems with legitimizing itself (producing one prediction that would be confirmed by observations). The "pure" GR doesn't have these problems (e.g. it doesn't need the existence of "dark energy"). The "pure GR" is from 1916 and it turns out that it predicts also the Hubble redshift with Hubble constant H_o=c/R_E (where R_E is "Einstein's radius"), illusion of accelerating expansion as observed, 'anomalous' acceleration of Pioneers as observed, local quasars as observed, etc.
Had the scientific journals published the news about 1916 GR predicting Hubble redshift the mainstream would have to prove that the universe is expanding and that it is not merely an assumption of some astronomers. For the time being scientific journals ignore the news as probable but
not interesting enough to their readers and therefore if published it would take room that might be used for more interesting news. So the Big Bang turns out to be based only on the lack of interest in reality of readers of scientific journals (at least according to their editors).
Luckily, whoever is interested in reality may read ATM publications (for limited time though) and learn how the reality might look like. And if he/she think that reality can't be like then he/she's free to present his/her objections. Does not happen very often though (if ever, since at least nobody ever argued his/her point against mine yet, in over 20 years). Even Ned Wright who specializes in destroying ATM ideas, preferred policy of "wait and see", instead of destroying the idea of "Einstein's universe" with its "uninteresting" Einsteinian math. Apparently not many people are willing to make fools of themselves when the Big Bang collapses in some more or less distant future.
Quote:
Originally Posted by Fortis
You make the usual cosmological assumptions regarding the symmetry of spacetime time; effectively saying that the universe looks pretty much the same, on a large scale, regardless of where you happen to be. This gives you a solution (and metric) that has some constants still to be defined. When you plug this into the Einstein field equations you recover the time dependance of this solution and it is an expanding or contracting universe. It is only when you set the cosmological constant to a specific, very tuned, value that you obtain a static solution.
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That's true for FRW model, but there is a problem with establishing a metric for Einstein's universe (not a problem with cosmological constant though) since it follows from certain considerations that this metric is non Riemannian (it is degenerate - at least the one that I could guess so far: spacetime has zero volume

).
Quote:
Originally Posted by Fortis
It doesn't look at all Newtonian to me.
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The math is not Newtonian but the physics is. It still suggests "tremendous" gravitational force pulling the universe together (through the vacuum). My guess (as an explanation of behavior of theorists) is that the teorists don't understand the physics of gravitaion. And that's why one of the leading Big Bang theorists, John Baez, produced a sentence: "
"It is always surprising when it happens, but sometimes to learn more about the world we must stop asking certain questions... ... namely, those based on false assumptions." One of those false assumptions, according to theorists, is an assumption that energy is conserved in gravitation. Which I proved just with differentiating E=MC^2. Yet it can't be published outside ATM. So officially, despite the exstence of Einsteinian physics, can't be published in a scientific journal (rejected by the referee for problems with relating it to infinity

). But existence of "tremendous" gravitational force pulling the universe together, as expressed by Ned Wright, a mainstream scientist, can.
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Originally Posted by Fortis
I'm confused because the mainstream view of GR is that you don't have "spooky action at a distance". This was actually Einstein's view of the weirdness of quantum mechanics. In mainstream GR objects follow geodesics of space time, and hence their path is defined by the local geometry of the spacetime that they encounter.
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This is example of magic in science. Math (GR) goes one way and physics (the Big Bang) goes the other. If all fragments of the uiverse just follow their geodesics, from what theory this "tremendous" gravitational force pulling the universe together that has to be opposed by "dark energy" pushing the uiverse appart is coming from?
Quote:
Originally Posted by Fortis
As an aside, you appear to treat conservation of energy seperately to conservation of momentum. As these two quantities together make up the 4-momentum, should you not also treat the 3-momentum in an analogous way to the way that you treat the energy?
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I do of course. Energy and momentum are conserved separately as well. This is elementary physics. Without this fact it wouldn't be possible to solve many first year physic problems, since you wouldn't have enough equations to desribe a system. It is in "The Feynman lectures on physics" (I don't remember the page, but I didn't make it up

).