AST-713intermediate

Acoustic Peaks: Physical Mechanisms

The acoustic peaks in the CMB power spectrum are fossils of sound-like oscillations in the tightly coupled photon-baryon plasma before recombination. Peak structure determines baryon density, matter density, curvature, the sound horizon, and combinations of cosmological parameters with remarkable precision.

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Acoustic Peaks: Physical Mechanisms

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AST-712Acoustic Peaks: Structures & Vocabulary→

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AST-714Acoustic Peaks: Observation, Measurement & Evidence→

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The acoustic peaks in the CMB power spectrum are fossils of sound-like oscillations in the tightly coupled photon-baryon plasma before recombination.

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A perturbation begins falling gravitationally, compressing the photon-baryon fluid until pressure reverses the motion.

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WMAP and Planck measured multiple acoustic peaks with positions and amplitudes closely matching cosmological models based on adiabatic primordial perturbations and standard plasma physics.