What Does Gravity Have To Do WithThe Expanding Universe?

[Anomalocaris]

Was spacetime ever curved? Light (photons, energy) curves when it comes within the vicinity of a body of matter. But in the beginning there was no matter, ergo, no gravity until  recombination.  Wouldn't that make spacetime/energy that isn't within the vicinity of a body of matter linear rather than curved and that would also account for acceleration.

The universe doesn't orbit around a center like matter does. It just moves outward

I think the highlighted part is not accurate for two reasons:

1.  Matter with rest mass in the form of electrons and protons existed before recombination.  Recombination simply allows electron and protons to combined to form electrically neutral matter that is transparent to light.  Recombination was the first moment in the history of the universe when photons could propagate through space without being absorbed by charged particles.   So it is the earliest moment that we can look back in time by looking out through 13 billion light years to actually see matter.  Prior to that space itself was filled with ionized matter but was opaque, so we’ll see nothing if we try to use photons to see back further.  But matter definitely existed before that time.

2.  Even before electrons and protons themselves first formed,  the energy that will eventually become electrons and positrons had already existed since the Big Bang itself.  Energy by E=MC^2 is equivalent to mass and for that reason excerpts its own gravity.   Photons, for example, possesses its own gravity.  The gravity is very small because by E=MC^2, even the energy of the most energetic photons is equivalent to only an infinitesimal amount of mass.   But Wherever there is net positive energy, regardless of whether the Nagy is in the form of matter with rest mass, or particle without test mass, there is essence of what curves space time and hence there is granvity.  Matter strictly in the forms colloquially called matter is not required.   The curvature of the entire universe was affected (but not necessarily dominated) by gravity the moment it was created in the Big Bang.

Also, Since universe is open, this means space is hyperbolically curved on a cosmological scale by an amount greater than collective gravity of all mass and energy in the universe can cancel out.   So curvature of space time does not just occur locally under local gravity in the vicinity of great masses.

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Astrologers? You didn't eat your Wheaties this morning, did you, Anom?

I have total confidence in the ability of ignorance and superstition to outlast everything else and still be there at the heat death of the universe.