Can't we simply assume that the initial condition for the universe is perfectly spherically symmetric, and the problem is solved? In other words, can't we make the CMB homogeneous just by imposing homogeneous initial conditions? The fluctuations can be explained by quantum effects. Of course there are other things such as the flatness problem which seem to be quite naturally explained by inflation, but I never feel sure about the homogeneity problem. After all, we know very little about how the big bang happened, and we can't rule out any particular kind of initial conditions, such as a homogeneous one.(adsbygoogle = window.adsbygoogle || []).push({});

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# Why do we need inflation to explain the homogeneity of CMB?

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