- #1

victorvmotti

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- TL;DR Summary
- In the early universe, with smaller scale factor and with density perturbations, is homogeneous density still valid? Isn't this a contradiction?

When arriving at the standard model of cosmology, i.e. the exapnding universe, we assume based on experirmental data that the cosmos is homogenous on large enough scales.

But when we go back in time, when the galaxies are beginning to form, we note that because of the growth of density perturbation, these gravitationally bound systems can emerge after cooling down due to expansion.

Isn't the density perturbation in the early universe a contradition with the present homogeneous density used to arrive at the exapnding model with an scale factor.

Is there a cut off time in the past that the scale factor used in the metric fails to be a valid theory?

But when we go back in time, when the galaxies are beginning to form, we note that because of the growth of density perturbation, these gravitationally bound systems can emerge after cooling down due to expansion.

Isn't the density perturbation in the early universe a contradition with the present homogeneous density used to arrive at the exapnding model with an scale factor.

Is there a cut off time in the past that the scale factor used in the metric fails to be a valid theory?