This is a follow up to an old thread: https://www.physicsforums.com/threads/the-first-acoustic-peak-in-cmb.475412/. In the final draft of the Plank study - http://arxiv.org/pdf/1303.5076v3.pdf - they quote the sound horizon at 1.04147 x 10(adsbygoogle = window.adsbygoogle || []).push({}); ^{-2}. This equates to a multipole moment of 302. However, if you look at the diagram of the power curve, the first peak is at roughly 220.

In the earlier post, someone suggested that there was a phase shift, but if you actually calculate the phase shift from the referenced document - using the r_{*}from the Plank study - you get a factor of 0.5. So 302 x 0.5 = 150 which still doesn't equal a multipole moment of 220. So what is the relation between the quoted sound horizon of 0.0104147 and the first acoustic peak at a moment of 220?

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# How is the first peak of the CMB calculated?

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