讨论:物理常数
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物理常数属于维基百科自然科学主题物理类的基础条目第五级。请勇于更新页面以及改进条目。 本条目页依照页面品质评定标准被评为列表级。 本条目页属于下列维基专题范畴: |
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请帮忙把以下这段从英文版转过来的简介译成中文,再放在前头。谢谢。--石添小草 07:05 2004年4月30日 (UTC)
In science, a physical constant is a physical quantity whose numerical value does not change. It can be contrasted with a mathematical constant, which is a fixed value that does not directly involve a physical measurement.
There are many physical constants in science, some of the most famous being: Planck's constant, the gravitational constant, and Avogadro's constant (better known as Avogadro's number). Constants can take many forms: the Planck length represents a fundamental physical distance; the speed of light in a vacuum signifies a maximum speed limit of the universe; and the fine-structure constant, which characterizes the interaction between electrons and photons, is dimensionless.
Beginning with Dirac in 1937, some scientists have speculated that physical constants may actually decrease in proportion to the age of the universe. Scientific experiments have not yet pinpointed any definite evidence that this is the case, although they have placed upper bounds on the maximum possible change per year at very small amounts (roughly 10-5 per year for the fine structure constant α and 10-11 for the gravitational constant G).
If the physical constants had slighlty different values, our universe would be so different that intelligent life would probably not have emerged: our universe seems to be fine-tuned for intelligent life.
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建议
很多基本的物里常数都没有刊写上
一开使就一大堆近物的物理常数
这样对物理系的学生 没有帮助吧!