# Is this possible?

Discussion in 'Physics & Math' started by curioucity, Jul 31, 2003.

1. ### spoilsportRegistered Senior Member

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While that is true I think people tend to think of weight as the net downward force you apply to the surface of the earth, or basically, what the scale says when you stand on it. If you think of it that way, the balloon has a negative weight.

If by weight you mean the force of gravity between the balloon and the earth, then you have a very different picture.

Also, negative mass would create negative weight because it would be repelled by positive mass (supposedly, if it weren't, why would the mass be negative?).

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3. ### ShalashaskaRegistered Member

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It's negative because it has less than no mass, like a rip in space. However, I really don't think it would be possible...if there were signifigant amounts of negative matter wouldn't it change the universal amount of matter, then we'd need *alot* more dark matter to make up for it.

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5. ### Merlijncurious catRegistered Senior Member

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1,014
No negative mass.

If you think of mass as that which works against acceleration, there does not seem to be a possibility for negative mass.

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7. ### spoilsportRegistered Senior Member

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90
Oooh, I hadn't even thought of that. A negative mass would have negative inertia and when moving, negative momentum. Yeah, I think negative mass is too screwy to even think about.

8. ### AbsaneRocket SurgeonValued Senior Member

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Are the formulas such as p = mv based on the assumption of positive mass? I mean, anything developed from there would obviously be wrong, correct?

9. ### PeteIt's not rocket surgeryRegistered Senior Member

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Do you think you could find a supporting reference?
I don't mean to offend, but I don't want to base a major shift in viewpoint on an unsupported assertion from "someone on the Internet".

10. ### Emil SmejkalRegistered Senior Member

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Is it good question - about negative mass?
Why?
What is atribut of good question?
Which questions are more attractive: trivial, or magic complicate?

Emil

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12. ### PeteIt's not rocket surgeryRegistered Senior Member

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The first and third references confirm my understanding that negative energy density particles are the stuff of pure theory, and have never been detected.

From the Nature article:
<blockquote>Six years ago, Visser and his colleague David Hochberg showed that in order to stay open, wormholes need exotic matter. It's weird stuff, however - it can be considered to have negative energy, meaning that it has even less than empty space. It's the same as saying that it experiences gravity as a repulsive force, and physicists have never encountered anything of the sort.</blockquote>

The second references appears to refer to particles with positive mass only. I can't find anywhere in the paper that refers to negative energy density particles:
<blockquote>We find some long-lived strangelet candidates which are highly negatively charged with a mass to charge ratio like a anti deuteron (M/Z ~ −2) but masses of A=10 to 16.</blockquote>

13. ### AbsaneRocket SurgeonValued Senior Member

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I mean anything developed from these for negative mass. Shouldn't p = mv actually be p = mv where m >= 0? No one has observed negative mass to know how to treat it mathematically, unless it can be proven otherwise.