Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary particles, theoretically with the same amount of matter, have nonetheless different masses. Mass in modern physics has multiple definitions which are conceptually distinct, but physically equivalent.

【 在 imlepton 的大作中提到: 】
: 在地球上重力没了，当然质量的概念就没了。两个质量，和距离。距离还在，只能质量变成0
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FROM 114.255.101.*