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2016-06-02. Universe expanding faster than expected.

posted Jun 21, 2016, 9:06 PM by Alan Gould   [ updated Jun 21, 2016, 9:23 PM by Alan Gould ]
By Robert Sanders, UC Berkeley News. For GSS A Changing Cosmos chapters 4 and 9. Excerpt: Astronomers have obtained the most precise measurement yet of how fast the universe is expanding, and it doesn’t agree with predictions based on other data and our current understanding of the physics of the cosmos. The discrepancy — the universe is now expanding 9 percent faster than expected — means either that measurements of the cosmic microwave background radiation are wrong, or that some unknown physical phenomenon is speeding up the expansion of space, the astronomers say. ...By measuring about 2,400 Cepheid stars in 19 nearby galaxies and comparing the apparent brightness of both types of stars, the researchers accurately determined the true brightness of the Type Ia supernovae. They then used this calibration to calculate distances to roughly 300 Type Ia supernovae in far-flung galaxies. “We needed both the nearby Cepheid distances for galaxies hosting Type Ia supernovae and the distances to the 300 more-distant Type Ia supernovae to determine the Hubble constant,” Filippenko said. “The paper focuses on the 19 galaxies and getting their distances really, really well, with small uncertainties, and thoroughly understanding those uncertainties.”...  http://news.berkeley.edu/2016/06/02/universe-expanding-faster-than-expected/ 0