Talk:Exotic matter

message: Changed theoretical to hypothetical since there is no empirical support for the existence of such particles.
For example, neutrinos were once "purely theoretical" in that they had not been observed, but their existence was predicted to explain certain mass defects in nuclear processes, and the resulting violation of the law of energy conservation.
For these particles with negative mass, however, as well as for tachyons, for example, not even indirect or theoretical evidence for their existence exists.
Aragorn2 18:56, 25 Sep 2003 (UTC)
thread_title:  Just a hypothesis 

message: Negative mass would produce "negative gravity" that repels ordinary positive mass, but would be attracted to positive mass and other negative mass particles in a normal matter.
:The sentence contradicts itself. First it says that negative mass repels positive, but then it says that it attracts it. Paranoid 23:10, 18 Dec 2004 (UTC)
replies: text: Not quite. A negative mass particle repels positive mass particles away from it, and is itself attracted towards positive mass particles. So if you had two particles sitting next to each other, one positive mass and the other negative mass, the two particles would both start accelerating in the direction of the positive mass particle. This doesn't violate any conservation laws since as the positive mass gains positive energy and momentum the negative mass gains equal amounts of negative energy and negative momentum. Bryan 06:07, 19 Dec 2004 (UTC)
replies: text: This doesn't violate any conservation laws since as the positive mass gains positive energy and momentum the negative mass gains equal amounts of negative energy and negative momentum.
omg thnx for telling me that i always wondered lolz
Well, the argument above assumes that gravitational mass is the same as inertial mass. So, when we do assume this, and use a=F/m and F(grav)=-GmM/r^2, then substitution yields a=-GM/r^2 and acceleration is only dependent upon the attracting mass. Hence, Derksen's result.  But, if inertial mass and gravitational mass are different, then the m in the substitution does not cancel.
2601:6:6080:587:389D:6C5C:337:4A84 (talk) 01:49, 7 October 2014 (UTC)
thread_title:  Contradiction 

message: redirects here, but there's nothing in the article about it.  please don't do that. - Omegatron 00:55, May 2, 2005 (UTC)
: I removed the redirect, as you mentioned this article doesn't at the moment have anything to do with negative energy. Intangir 16:56, 3 May 2005 (UTC)
replies: text: Negative mass has negative rest energy, which is why I had created the redirect (the previous "negative energy" page was gibberish). This was discussed on Wikipedia:Pages needing attention/Physics, though the thread was archived to the discussion page after months of inactivity. This is the only suitable place I could see redirecting to, as it doesn't seem to be treated elsewhere, and the term "negative energy" most often comes up in context of negative mass (when discussing stabilization of wormholes and similar scenarios). The closest other context is discussions involving particles moving faster than light, but these typically posit complex rest masses, not negative ones. --Christopher Thomas 19:34, 1 September 2005 (UTC)

text: Hardly an expert here, but doesn't the classic E=mc2 formula indicate that negative mass is equivalent to negative energy? Substitute in a negative number for m and you get a negative result for E. The article also has some stuff on negative kinetic energy in the Forward's analysis section. Bryan 20:46, 28 August 2005 (UTC)
replies: text:  Actually, the full equation is e2=m2c4+p2c2, where p is momentum. Assuming no momentum gives us e2=m2c4. Normally from there, we take the principle square root, assuming mass and energy must be positive. But if we can't make that assumption, I don't see how that equation would imply that negative mass and negative energy are equivalent. Also, yeah i guess negative temperature would be a form of negative energy. Intangir 00:55, 29 August 2005 (UTC)

text:  If inertial mass = rest mass and is seen as the modulus of the gravitational mass (which can be +ve or -ve) then E=mc2 would always be positive. This ties in with the idea that negative energy would consist of negative photons, which are undefined since they are their own anti-particles. The only form of negative electromagnetic radiation I can think of is a reversed vibration in space-time ie real waves 1800 out of synch.Brian O'Donnell (talk) 19:07, 17 July 2008 (UTC)

text: I think it should be a real article about negativ energy. Negtive energi exists in quite non-exotic forms, for example the potential energy in a gravity field or the potential energy in an eletromagnetic field. That IS negative energy. In fact, matter/antimatter pair can be created in strong elektromagnetic fields so that the particles "pays" the energy for the mass by the energy of the potential energi. So it has nessecary not anything to do with exotic matter. There is also possible to argue that the universe total energy can be zero, because the gravitational potential energy is negative and the total sum may be zero. 83.241.133.2 12:20, 16 September 2005 (UTC)
replies: text: The distinction is that negative potential is completely arbitrary; it depends on what you define to be zero.  Example: does a rock two meters above the ground near sea level have the same potential as a rock two meters right above the top of a mountain? They will have (virtually) the same kinetic energy when they hit the ground. If you defined 0 height to be the top of the mountain, then the rock at sea level would have negative energy. If you defined 0 height to be sea level, then the rock at the top of the mountain would have a lot of potential. Potential is relative. - mako 22:32, 16 September 2005 (UTC)
replies: text:  The problem here is straightforward, ladies and gentlemen. This article is very uninformative on the topic on which I intended to be informed. Something relevant has been lost. Need there be further debate? 75.170.37.221 (talk) 00:08, 18 October 2010 (UTC)
thread_title:  [[negative energy]] 

message: "Certainly, this observation implies that their ratios differ only in sign, but it does not make clear whether it is charge or mass which is negative."
:but earlier you said that if a particle had negative mass, it would accelerate indefinitely and other bizarre effects.  i think this sentence may be talking about "intertial mass" and not just "mass" in general, though it's not clear to me what the difference is. - Omegatron 01:04, May 2, 2005 (UTC)
::Yes, i meant to say inertial mass there, I think I have clarified it now Intangir 16:37, 3 May 2005 (UTC)
thread_title:  antimatter negative mass or charge 

message: Why is "negativ energy" redirected to "exotic matter"? Negtive energi exists in quite non-exotic forms, for example the potential energy in a gravity field or the potential energy in an eletromagnetic field. That IS negative energy. In fact, matter/antimatter pair can be created in strong elektromagnetic fields so that the particles "pays" the energy for the mass by the energy of the potential energi. 83.241.133.2
:There are two talk sections in this page (both with "negative energy" in their headers) that discuss the whys of this. Bryan 15:20, 15 September 2005 (UTC)
thread_title:  Why redirect 

message: Someone had replaced the negative energy redirect page with a short rehash of some of the exotic matter and Alcubierre drive material.
As there was substantial protest over negative energy redirecting here, and as people had correctly pointed out that it's a term used with respect to several phenomena, I've turned it into a disambiguation page.
I hope that this rewrite is acceptable to anyone involved in the original discussions. --Christopher Thomas 05:52, 12 November 2005 (UTC)
replies: text: Excellent! Intangir 06:27, 13 November 2005 (UTC)
thread_title:  Negative energy (again) 

message: Negative mass would basicially result in the following:
*Negative moment of inertia
*Angular momentum switches sign
*Torque switches sign
*Kinetic energy switches sign
*Negative energy
However, if the length of such an object was imaginary:
*Imaginary velocity (velocity along one or more imaginary axes)
*Imaginary radius (radius along one or more imaginary axes)
*Angular momentum has the same sign
*Torque has the same sign
*Kinetic energy has the same sign
*Positive energy
As long as their masses are of the same sign for every action there is an equal and opposite reaction (Push for Push, and Pull for Pull).  But if their masses differ in sign, for every action their is an equal but not opposite reaction (Push for Pull, Pull for Push).  A negative mass implies either negative energy or movement along the complex plane(s).  Same sign masses would interact with less than 100% efficiency, where as the interaction between oppositely massed objects would have more than 100% efficiency.
Up.
Down.
Charm.
Strange.
Top.
Bottom.
Push for Pull, Pull for Push.
10^23 + cycles per second.  Non-stop.  No collapse.
Kmarinas86 14:47, 19 July 2006 (UTC)
thread_title:  Negative mass? 

message: The last section "Which way does antimatter fall?" is about antimatter. But the article is about exotic matter. What do I do with it?! --Yanwen 22:59, 24 September 2006 (UTC)
replies: text: Actually, the section doesn't look entirely irrelevant because it's discussing whether antimatter has negative gravitational mass, which is a characteristic of exotic matter. There may be a bit much here, though. If you want to get rid of some of it I'd suggest moving it to Gravitational interaction of antimatter. Bryan 23:27, 24 September 2006 (UTC)

text: Its relativent because antimatter is often confused to have negative mass.  This is because antimatter-matter reaction involves negative energy state(*), which Dirac discovered when he showed that the solution to combining quantum physics and special relativity. See Dirac Sea for more info.  (*)Side Note for clarification: Honestly I cannot remember if its the antimatter, that actual photon, or the virtual photon, that we attribute the negative energy state, so I am using the word "involves" here.Physics16 (talk) 15:20, 2 November 2011 (UTC)
thread_title:  Which way does antimatter fall? 

message: I have a question regarding F = ma implying that exotic matter would move in the opposite direction of the force applied. I thought that the acceleration term carried a direction aswell, wouldn't that then imply that it is accelerating in one direction and having a force applied in the opposite direction? I am probably missing something. Phoenix1177 20:49, 19 September 2007 (UTC)
replies: text: The problem with exotic matter is that it never acts the way you'd expect.  For so-called 'negative' matter, the gravitational mass and the inertial mass are opposite in sign.  So if I pull on it with the gravity of a normal positive mass, it will move towards the positive mass.  But at the same time, the negative mass repels the positive mass, so the positive mass is pushed away.  So if you had a negative mass next to an equal positive mass, the pair would accelerate and keep on going, maintaining the same separation between them.  Oddly, the pair's total kinetic energy apparently remains at zero.  This sort of thing is why I hope exotic matter doesn't exist outside of science fiction. Michaelbusch 21:04, 19 September 2007 (UTC)
replies: text: We would expect the same, if antimatter had negative mass, with a proton and an antiproton.  The force between them would be attractive, causing the proton to move towards the antiproton.  But since F=ma and m was negative, the antiproton would move away from the proton.  So surely the fact that this behaviour is never observed serves as sufficient proof that antimatter has positive mass.  So why, according to the article, is this considered questionable? Manwiththemasterplan 22:17, 30 October 2007 (UTC)

text: It isn't questionable, but it is very hard to observe due to the difficulty of making enough antimatter with sufficiently low energy to observe it interact gravitationally - although now that I think about it, something like CERN or Fermilab might not work properly if gravitational acceleration wasn't canceled out. Michaelbusch 22:32, 30 October 2007 (UTC)
thread_title:  Question 

message: Come on... that's like common knowledge...  Carbon nanotubes are talked about ALL the time.  I mean, fullerenes and carbon nanotubes have been studied since the 50s.  I think that particular "citation needed" should be removed.  Man, you guys really go overboard with those sometimes.  —Preceding unsigned comment added by 98.209.137.136 (talk) 07:47, 9 August 2008 (UTC)
thread_title:  Citation needed for nanotube creation? 

message: Reference 8 has an error at the end of it. It should read - http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/antimatter_fall.html
Can someone who knows how to, please correct it.--83.105.33.91 (talk) 11:48, 1 October 2008 (UTC)
thread_title:  Reference list error 

message: So, we've addressed imaginary masses, but what about complex ones?  They definitely have complex energies, and I have no idea what results that would have.  —Preceding unsigned comment added by Po8crg (talk • contribs) 14:26, 19 March 2010 (UTC)
replies: text: No, a particle with no mass always travels at the speed of light. A particle with positive mass-squared always travels below the speed of light. A particle with negative mass-squared (e.g., purely imaginary mass) always travels above the speed of light. (Actually this isn't quite true; a particle with negative mass-squared is infinitely unstable and won't get a chance to travel anywhere, but if that weren't true, it would always travel faster than light, and would in fact speed up as it loses energy.) See tachyon for details. --213.115.171.131 (talk) 02:10, 5 October 2014 (UTC)
thread_title:  Complex mass 

message: If the reverse were true, and antiparticles had negative inertial mass and the same charge, then the normal particle with positive inertial mass would be repelled by its antiparticle.
But it doesn't explain why negative mass and opposite charge is not possible.
:We don't know that they are NOT possible definitively.  -G (talk) 15:18, 23 June 2011 (UTC)
replies: text: Actually we kind of do, in that the particle cannot have both negative mass, negative energy, and negative charge. If it did then you would violate the principles of the Casmir Effect or particle would switch over to a positive charge and positive with less time than it takes for an atom to go a Plank second. Simply because the term we are talking about is either I believe the quotent of mass and energy (for one side to be dimensionless), it kind of has to be either/or, not both. Physics16 (talk) 15:13, 2 November 2011 (UTC)
thread_title:  Confusing sentence 

message: I have removed this from the article. I don't see what it has to do with exotic matter at all. Perhaps some of it could be sourced and adapted for the negative energy however.  Headbomb {talk / contribs / physics / books} 05:20, 2 May 2010 (UTC)
thread_title: Difficulties with Negative Energy

message: Most of the content of this article is about the negative mass and this content is now present in negative mass article, and little content about imaginary mass is now present in tachyon article, which has section about mass and other possible meanings of term "exotic matter" (which are mentioned in intro) were included here.
If turning this article into disambiguation page is really too radical change, then perhaps negative mass section could be shortened with  on top of it pointing to negative mass article. Imaginary mass section wouldn't really need to be shortened because it is already short. --antiXt (talk) 07:44, 25 July 2010 (UTC)
replies: text: Shortening with a  sounds reasonable. I could go for that. Headbomb {talk / contribs / physics / books} 13:23, 25 July 2010 (UTC)
replies: text: It is done. --antiXt (talk) 17:13, 27 July 2010 (UTC)
thread_title:  Moving content 

message: There was a section about complex energy/mass which had a statement saying tachyons are considered to be nonphysical so they couldn't interact with regular matter.
I have no idea what "nonphysical" is supposed to mean in the context of particle physics and it just sounded like nonsense technobabble written by an armchair physicist. Please correct me, and the edit, if I'm mistaken. But this is nonsense, so I removed it.
The closest thing I can think of to being "nonphysical" in this context would be virtual particles, but that's clearly not what's being discussed. 2607:FEA8:99E0:61D0:91AA:C76C:D65:FBE (talk) 20:03, 7 July 2023 (UTC)
thread_title:  Removed nonsense statement about complex energy