baryon acoustic oscillation

astronomy

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July 20, 2026

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Baryon acoustic oscillations (BAO) are a phenomenon in cosmology that provides a standard ruler for measuring the expansion of the universe. They are essentially fossilized sound waves that propagated through the early universe when it was a hot, dense plasma.12

These waves left an imprint on the distribution of matter, creating a characteristic scale. By measuring this scale in the large-scale structure of galaxies today, astronomers can determine distances and map the expansion history of the universe. This method is crucial for understanding dark energy and the overall composition of the cosmos.12

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Rashid Sunyaev
…Zeldovich predicted the existence of baryon acoustic oscillations, regions of dense gas where galaxies would have formed in the early universe and that would appear as brightness fluctuations in the CMB. These oscillations were first observed in 2001 by balloon-based microwave detectors. In 1972 Sunyaev and Zeldovich described the SZ…
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…Zeldovich predicted the existence of baryon acoustic oscillations, regions of dense gas where galaxies would have formed in the early universe and that would appear as brightness fluctuations in the CMB. These oscillations were first observed in 2001 by balloon-based microwave detectors. In 1972 Sunyaev and Zeldovich described the SZ…
Read More