“Can mass be a negative? if yes plz explain me…”
Negative mass is a hypothetical concept. In normal case mass is always positive as it is of one kind only.
Some argue that this (+ mass) is in our universe (?) and there is equal probability of having a negative mass somewhere else.
In Casimir Effect ( A quantum phenomena :: Find details at http://en.wikipedia.org/wiki/Casimir_effect) properties similar to the expectations from negative mass were reported. (i.e; then the force between two masses becomes repulsive)
The concept of negative mass and the consequences thereof are widely discussed in the theory of wormhole and related ideas.
The existence of negative mass will violate more than one conservation principles in its present form.
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