• Cosmologists Show Possibility of Negative Mass
    79 replies, posted
[quote]Negative mass is the hypothetical idea that matter can exist with mass of the opposite sign to the ordinary stuff. Instead of 2 kg, a lump of negative mass would be -2 kg. Nobody knows whether negative mass can exist but there have nevertheless been plenty of analyses to determine its properties. In particular, physicists have investigated whether negative mass would violate various laws of the universe, such as the conservation of energy or momentum and therefore cannot exist. These analyses suggest that although the interaction of positive and negative mass produces counterintuitive behaviour, it does not violate these conservation laws. Cosmologists have also examined the effect that negative mass would have on the structure of space-time and their conclusions have been more serious. They generally conclude that negative matter cannot exist because it breaks one of the essential assumptions behind Einstein’s theory of general relativity. Today, Saoussen Mbarek and Manu Paranjape at the Université de Montréal in Canada say they’ve found a solution to Einstein’s theory of general relativity that allows negative mass without breaking any essential assumptions. Their approach means that negative mass can exist in our universe provided there is a reasonable mechanism for producing it, perhaps in pairs of positive and negative mass particles in the early universe.[/quote] Article: [url]https://medium.com/the-physics-arxiv-blog/cosmologists-prove-negative-mass-can-exist-in-our-universe-250a980320a7[/url] Paper: [url]http://arxiv.org/abs/1407.1457[/url] The fact that it satisfies the dominant energy condition is interesting enough, but there's good reason to be skeptical: I'm pretty sure negative mass leads to causality violations. I'd still be willing to bet there is some mechanism we don't know of yet which will rule it out along with naked singularities.
I don't understand most of the words but basically if you eat it you'll lose weight right
ALCUBIERRE DRIVE HERE WE COME
[QUOTE=Bean Shoot;45417568]I don't understand most of the words but basically if you eat it you'll lose weight right[/QUOTE] Yes. Also, you will die. Also, your family will die. But no one else.
All this ghey nerd shit says to me is "mass effect"
[QUOTE=JohnnyMo1;45417527]Article: [url]https://medium.com/the-physics-arxiv-blog/cosmologists-prove-negative-mass-can-exist-in-our-universe-250a980320a7[/url] Paper: [url]http://arxiv.org/abs/1407.1457[/url] The fact that it satisfies the dominant energy condition is interesting enough, but there's good reason to be skeptical: I'm pretty sure negative mass leads to causality violations. I'd still be willing to bet there is some mechanism we don't know of yet which will rule it out along with naked singularities.[/QUOTE] I'm actually more interested in the implications for gravitational waves mentioned in the article, since this is something that has been puzzling me for a while. It's always exciting if experiments don't turn out as they should [IMG]http://www.c3airsoft.com/images/smilies/science.gif[/IMG] Also: [quote]Karl Schwarzschild[/quote] I had no idea that this is an actual person's name! "Schwarzschild-Radius" in German literally means "black shield radius", which is so incredibly apt that I never thought twice about the origin of the word :v:
So FTL travel when?
[QUOTE=JohnnyMo1;45417604]Yes. Also, you will die. Also, your family will die. But no one else.[/QUOTE] Only his "dad" is left.
[QUOTE=Tamschi;45417735]I'm actually more interested in the implications for gravitational waves mentioned in the article, since this is something that has been puzzling me for a while. It's always exciting if experiments don't turn out as they should [IMG]http://www.c3airsoft.com/images/smilies/science.gif[/IMG] Also: I had no idea that this is an actual person's name! "Schwarzschild-Radius" in German literally means "black shield radius", which is so incredibly apt that I never thought twice about the origin of the word :v:[/QUOTE] My GR professor is a super smart dude and a string theorist but man did it get on my nerves when he pronounced it "Schwarz-child." [editline]17th July 2014[/editline] [QUOTE=sloppy_joes;45417765]Only his "dad" is left.[/QUOTE] also the mailman died
[QUOTE=Laserbeams;45417748]So FTL travel when?[/QUOTE] Probably never.
The internet actually explained this in layman's terms awhile ago [img]http://2.bp.blogspot.com/-ryvRexGEQf0/UA1_dX0ppAI/AAAAAAAAAXQ/YoEstlqM8Sc/s1600/troll%2Bscience%2Bnegative%2Bweight.jpg[/img]
Would two bodies of negative mass be attracted to each other like two bodies of partitive mass are? Would positive and negative mass repel each other?
[QUOTE=download;45417826]Would two bodies of negative mass be attracted to each other like two bodies of partitive mass are? Would positive and negative mass repel each other?[/QUOTE] Everything is attracted to positive masses and repelled from negative masses. So two negative masses would repel away from each other. Also, a negative mass would essentially chase a positive mass. The positive mass is trying to move away from the negative and the negative is trying to move toward the positive.
[QUOTE=JohnnyMo1;45417901]Everything is attracted to positive masses and repelled from negative masses. So two negative masses would repel away from each other. Also, a negative mass would essentially chase a positive mass. The positive mass is trying to move away from the negative and the negative is trying to move toward the positive.[/QUOTE] So, my love life?
[QUOTE=JohnnyMo1;45417901]Everything is attracted to positive masses and repelled from negative masses. So two negative masses would repel away from each other. Also, a negative mass would essentially chase a positive mass. The positive mass is trying to move away from the negative and the negative is trying to move toward the positive.[/QUOTE] Wouldn't that violate conservation of energy though? I mean I know that law only arises because all known forces are conservative, but in the example above you'd basically have a perpetuum mobile of a magnitude and likelihood that should be observable. (I'm not too good with general relativity yet though, so I have no idea whether the difference in clock speeds would destabilise the system.) [editline]17th July 2014[/editline] Unless this is "dark energy" of course, then negative-mass particles would solve a few questions at once (but be incredibly boring due to not interacting with normal matter very much). [editline]17th July 2014[/editline] [QUOTE=JohnnyMo1;45417766]My GR professor is a super smart dude and a string theorist but man did it get on my nerves when he pronounced it "Schwarz-child."[/QUOTE] I can relate, this happens at least once every single time I hear someone try to speak German not very successfully :v: There are actually a few dialects here that substitute "ch" for "sch", but the German "ch" is/are a lot different from the English version(s) too.
[QUOTE=Tamschi;45418027]Wouldn't that violate conservation of energy though? I mean I know that law only arises because all known forces are conservative, but in the example above you'd basically have a perpetuum mobile of a magnitude and likelihood that should be observable. (I'm not too good with general relativity yet though, so I have no idea whether the difference in clock speeds would destabilise the system.)[/QUOTE] It certainly seems like it should violate conservation of energy and momentum, but the negative mass means the negative mass particle has negative kinetic energy and momentum. The energy and momenta of the particles cancel out.
[QUOTE=JohnnyMo1;45418254]It certainly seems like it should violate conservation of energy and momentum, but the negative mass means the negative mass particle has negative kinetic energy and momentum. The energy and momenta of the particles cancel out.[/QUOTE] How can it have negative kinetic energy if energy is a scalar this whole thing just screams "we're thinking theoretically and not actually trying to be realistic here"
[QUOTE=JgcxCub;45418282]How can it have negative kinetic energy if energy is a scalar this whole thing just screams "we're thinking theoretically and not actually trying to be realistic here"[/QUOTE] Scalars can be negative. Any real number is a scalar. Also, the dominant energy condition is their way of imposing "realism" beyond just having it satisfy the Einstein field equations. The DEC is actually pretty restrictive.
So does it actually do anything for us
[QUOTE=Complifused;45418305]So does it actually do anything for us[/QUOTE] You mean... beyond progressing our understanding of the the universe?
[QUOTE=Complifused;45418305]So does it actually do anything for us[/QUOTE] Any progress towards basic understanding of how the universe works is useful for us in general. We may not know exactly how useful it is at first, but science and time will both tell.
I'm very skeptical about this, but does it also imply negative energy?
I wonder if anyone else been in a complicated situation and said out-loud to themselves, "man, I wish JohnnyMo were here to explain this fuckin' shit."
[QUOTE=MatheusMCardoso;45418430]I'm very skeptical about this, but does it also imply negative energy?[/QUOTE] Any energy can be considered negative if your reference point is an amount of energy that is higher.
[QUOTE=_Axel;45418650]Any energy can be considered negative if your reference point is an amount of energy that is higher.[/QUOTE] For potential energy, yes, but this is talking about negative rest energy.
[QUOTE=Laserbeams;45417748]So FTL travel when?[/QUOTE] You cannot travel faster than light.
so wait, if the negative mass chases after the positive and the positive runs away from the negative doesn't this mean you can make a perpetual motion machine out of them?
[QUOTE=Doom64hunter;45418676]You cannot travel faster than light.[/QUOTE] but muh infinite improbability drive
[QUOTE=MatheusMCardoso;45418430]I'm very skeptical about this, but does it also imply negative energy?[/QUOTE] I don't think that it does. The dominant energy condition implies that energy density is everywhere positive, but this spacetime has a negative ADM mass. I don't really know enough about the ADM formalism to figure out how it can be negative and get by without negative energy.
Alcubierre drives use negative mass if I'm not mistaken. Win.
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