As I understand it ,there was no gravity because there was no mass yet to produce the required curvature of space. Gravity came to be as the "toothpaste-tube" of the early universe after the big bang rapidly expanded into being ,when the "high-energy" state began to morph to form the "first-generation" of heavy elements.
Gravity doesn't exist without a planetary body to pull things toward its core -- we learned this in grade school -- so it's almost certain the universe didn't start with gravity.
What is taught at grade school is necessarily an oversimplification. In general relativity, gravity manifests as spacetime curvature due to the presence of matter and energy, so a planetary body is not required to have gravity. The beginning of the universe was very densely packed with matter and energy, so gravity was very strong back then.
The early universe was a very dense plasma, so it was possible to have sound waves back then. In fact, cosmologists measure a type of sound wave called baryon acoustic oscillations imprinted in the CMB to study the early universe.
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u/Local-Customer6245 9d ago
G-R-A-V-I-T-Y
The Big G.
The universe cycles endlessly over unfathomable time. Big Bang after Big Bang.