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Old 08-09-2002, 08:05 PM   #1
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Post What about "Negative" matter?

That is to say, matter which is (probably among other things) repellant to gravity. If dropped, it would "float up".

Could this stuff exist anywhere in the universe?
Can it be created, and if so, how?
What would be the potential danger/s of it?
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Old 08-09-2002, 09:22 PM   #2
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As far as I know, "negative matter" is not currently even a theoretical possibility, so to answer your questions:

1) No. Well, it is not a theoretical possibility, but it is a logical possibility, so I can't quite rule it out entirely. It's near enough that I can ignore the possibility though.

2) No. As I said it is not a theoretical possibility, so creating it pretty much out of the question.

3) None. Well, other than experiencing gravity negatively you have assigned it no properties so it is impossible to speculate on what dangers it might present if it did exist, which it doesn't.
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Old 08-09-2002, 10:10 PM   #3
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There are actually quite a few equations that can allow for negative mass, but no evidence as of yet for it.

<a href="http://www.physlink.com/Education/AskExperts/ae257.cfm" target="_blank">http://www.physlink.com/Education/AskExperts/ae257.cfm</a>
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Old 08-09-2002, 10:26 PM   #4
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Interesting. Would that make it a theoretical possibility as well as a logical possibility? I'm not sure.
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Old 08-10-2002, 12:36 AM   #5
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What? Not even anti-matter have negative mass, so how can anything else have negative mass?
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Old 08-10-2002, 02:17 AM   #6
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Question

What is mass?

(sorry, I ask this question on a fairly regular basis, feel free to ignore it )
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Old 08-10-2002, 02:38 AM   #7
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Cool

Measurements for electron neutrino mass
The mass of electron neutrinos is measured in tritium beta decay experiments. The decay results in a 3-helium, electron and an electron antineutrino. If neutrinos have non-zero mass, the spectrum of the electrons is deformed at the high energy part, i.e. the neutrino mass determines the maximum energy of emitted electrons.

To be excact, the experiments measure the neutrino mass squared. Curiously, when taken at the face value, all results point to a negative mass squared, particularly the oldest experiment. This is probably due to a systematic error, and actually two running experiments, Mainz and Troitsk, have been able to measure physically acceptable values.

<a href="http://cupp.oulu.fi/neutrino/nd-mass.html" target="_blank">http://cupp.oulu.fi/neutrino/nd-mass.html</a>
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Old 08-10-2002, 05:38 AM   #8
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I thought it was possible. In fact I thought you could get negative energy as well (and no, not the hippy variety...). <a href="http://www.physics.hku.hk/~tboyce/sf/topics/wormhole/wormhole.html" target="_blank">This old Scientific American had some stuff about it (yeah sorry it's "cheating" but I haven't got the time to write it all out in my own words...)</a>

I also thought that Hawking radiation (when a Black hole "evaporates") relayed on it, if anyone's got a copy of Brief History of Time handy have a look at it on page 116-118). Although it does imply that it is very rare for a negative energy particle to have a "Real existence" (real being as in the Real vs Virtual sense of particle physics)
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Old 08-10-2002, 10:50 AM   #9
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I suppose if there was such a thing it would have separated from the positive matter long ago. After all, they would repel each other.

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Old 08-10-2002, 11:30 AM   #10
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negative energy exists, hence negative mass exists as well.
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