
Originally Posted by
SpaceCadet
What kind of object can you imagine that would have negative mass? If an object exists, it's almost certainly going to have some mass, or zero mass at least. Of course, this is only common sense, and common sense is not always a good guide to the universe.
But consider the lines from the very beginning of the article that you posted:
"The idea of a negative mass is conjectural, since no material object has ever been found that can be shown by experiment to have a negative mass. Nevertheless, it will be shown below that the mass equivalent of the energy in a gravitational field is negative, therefore, it may be instructive to speculate on the physics of negative mass."
No object, anywhere in the universe, in any experiment, down to the subatomic level and up to the size of the entire universe itself, has ever been found which would so much as hint that such a thing is possible. Perhaps more importantly, I'm not aware of any physical theory in existence that even hints at such a thing. There could very well be such an idea out there that I'm not aware of, but I doubt very much that it would be a mainstream theory or anything more than conjecture, as in the case of this article. Not being a professional string theorist, perhaps there is some strange consequence of a theory such as that which would possibly produce something that weird. I can't say with absolute certainty that there isn't, although I don't recall having ever read about anything like that.
The "mass equivalence" of a field is not the same thing as the mass of an actual object.
Anyway, I was just trying to get some idea of what the OP was getting at, and he doesn't seem to be in any hurry to tell us.
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