2005/05/21 | 宇宙[Universe]
类别(¤〖天文〗) | 评论(0) | 阅读(55) | 发表于 20:37
The age of the universe can be estimated using several techniques.

1. Radioactive dating yields an age of the solar system of about 4.6 billion years. This is a measure of the time since solidification.
2. globular cluster Hertzsprung-Russell diagram fitting yields an age of 9-18 billion years.
3. The Hubble method, taking where H is the Hubble constant, yields 15 billion years.
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