Top Document: [sci.astro] Cosmology (Astronomy Frequently Asked Questions) (9/9) Previous Document: I.08. If the Universe is only 10 billion years old, how can we see objects that are now 30 billion light years away? Why Next Document: I.10. What is the Universe expanding into? See reader questions & answers on this topic! - Help others by sharing your knowledge Obviously, the Universe has to be older than the oldest stars in it. So this question basically asks, which estimate is wrong: * The age of the Universe? * The age of the oldest stars? or * Both? The age of the Universe is determined from its expansion rate: the Hubble constant, which is the ratio of the radial velocity of a distant galaxy to its distance. The radial velocity is easy to measure, but the distances are not. Thus there is currently a 15% uncertainty in the Hubble constant. Determining the age of the oldest stars requires a knowledge of their luminosity, which depends on their distance. This leads to a 25% uncertainty in the ages of the oldest stars due to the difficulty in determining distances. Thus the discrepancy between the age of the oldest things in the Universe and the age inferred from the expansion rate is within the current margin of error. User Contributions:Top Document: [sci.astro] Cosmology (Astronomy Frequently Asked Questions) (9/9) Previous Document: I.08. If the Universe is only 10 billion years old, how can we see objects that are now 30 billion light years away? Why Next Document: I.10. What is the Universe expanding into? Part0 - Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Part8 - Single Page [ Usenet FAQs | Web FAQs | Documents | RFC Index ] Send corrections/additions to the FAQ Maintainer: jlazio@patriot.net
Last Update March 27 2014 @ 02:11 PM
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