Editing Exotic matter

{{Short description|Physics term for multiple concepts}}
{{Use dmy dates|date=June 2016}}

There are several proposed types of '''exotic matter''':

* [[Hypothetical particle]]s and states of matter that have not yet been encountered, but whose properties would be within the realm of mainstream physics if found to exist. 
* Several particles whose existence has been experimentally confirmed that are conjectured to be [[exotic hadron]]s and within the [[Standard Model]].
* [[State of matter|States of matter]] that are not commonly encountered, such as [[Bose–Einstein condensate]]s, [[fermionic condensate]]s, [[nuclear matter]], [[quantum spin liquid]], [[string-net liquid]], [[supercritical fluid]], [[color-glass condensate]],  [[quark–gluon plasma]], [[Rydberg matter]], [[Rydberg polaron]], [[photonic matter]], [[Wigner crystal]],<ref>{{Cite journal |last=Tsui |first=Yen-Chen |last2=He |first2=Minhao |last3=Hu |first3=Yuwen |last4=Lake |first4=Ethan |last5=Wang |first5=Taige |last6=Watanabe |first6=Kenji |last7=Taniguchi |first7=Takashi |last8=Zaletel |first8=Michael P. |last9=Yazdani |first9=Ali |date=2024-04-10 |title=Direct observation of a magnetic-field-induced Wigner crystal |url=https://www.nature.com/articles/s41586-024-07212-7 |journal=Nature |language=en |volume=628 |issue=8007 |pages=287–292 |arxiv=2312.11632 |doi=10.1038/s41586-024-07212-7 |issn=1476-4687}}</ref> [[Superfluidity|Superfluid]] and [[time crystal]] but whose properties are entirely within the realm of mainstream physics.
* Forms of matter that are poorly understood, such as [[dark matter]] and [[mirror matter]].
* Ordinary matter that when placed under [[high pressure]], may result in dramatic changes in its physical or chemical properties.
* [[Degenerate matter]]
* [[Exotic atom]]s

== Negative mass ==
{{Main|Negative mass}}

Negative mass would possess some strange properties, such as accelerating in the direction opposite of applied [[force]]. Despite being inconsistent with the expected behavior of "normal" matter, negative mass is mathematically consistent and introduces no violation of [[conservation of momentum]] or [[conservation of energy|energy]]. It is used in certain speculative theories, such as on the construction of artificial [[wormhole]]s and the [[Alcubierre drive]]. The closest known real representative of such exotic matter is the region of pseudo-[[Pressure#Negative pressures|negative-pressure]] density produced by the [[Casimir effect]].

== Complex mass ==
{{Main|Tachyon#Mass}}

A hypothetical particle with complex rest mass would always travel faster than the [[speed of light]]. Such particles are called [[tachyon]]s. There is no confirmed existence of tachyons.

: <math>E = \frac{m\cdot c^2}{\sqrt{1 - \frac{\left|\mathbf{v}\right|^2}{c^2}}}</math>

If the rest mass <math>m</math> is complex this implies that the denominator is complex because the total energy is [[observable]] and thus must be [[real number|real]]. Therefore, the quantity under the square root must be negative, which can only happen if [[speed|''v'']] is greater than [[speed of light|''c'']]. As noted by [[Gregory Benford]] ''et al.,'' [[special relativity]] implies that tachyons, if they existed, could be used to communicate backwards in time<ref>{{cite journal|author1=G. A. Benford |author2=D. L. Book |author3=W. A. Newcomb |year=1970|title=The Tachyonic Antitelephone|journal=[[Physical Review D]]|volume=2 |issue=2 |page=263|doi=10.1103/PhysRevD.2.263|bibcode = 1970PhRvD...2..263B }}</ref> (see [[tachyonic antitelephone]]). Because [[time travel]] is considered to be non-physical, tachyons are believed by physicists either not to exist, or else to be incapable of interacting with normal matter.

In [[quantum field theory]], complex mass would induce [[tachyon condensation]].

== Materials at high pressure ==
At high pressure, materials such as [[sodium chloride]] (NaCl) in the presence of an excess of either chlorine or sodium were transformed into compounds "forbidden" by classical chemistry, such as {{chem|Na|3|Cl}} and {{chem|Na|Cl|3}}. Quantum mechanical calculations predict the possibility of other compounds, such as {{chem|Na|Cl|7}}, {{chem|Na|3|Cl|2}} and {{chem|Na|2|Cl}}. The materials are thermodynamically stable at high pressures. Such compounds may exist in natural environments that exist at high pressure, such as the deep ocean or inside [[planetary core]]s. The materials have potentially useful properties. For instance, {{chem|Na|3|Cl}} is a two-dimensional metal, made of layers of pure sodium and salt that can conduct electricity. The salt layers act as insulators while the sodium layers act as conductors.<ref>{{cite web |url=http://www.gizmag.com/scientists-create-forbidden-compounds-table-salt/30520/ |title=Scientists turn table salt into forbidden compounds that violate textbook rules |date=21 January 2014 |publisher=Gizmag.com |access-date=2014-01-21 |archive-date=22 January 2014 |archive-url=https://web.archive.org/web/20140122075204/http://www.gizmag.com/scientists-create-forbidden-compounds-table-salt/30520/ |url-status=live }}</ref><ref>{{Cite journal | last1 = Zhang | first1 = W. | last2 = Oganov | first2 = A. R. | last3 = Goncharov | first3 = A. F. | last4 = Zhu | first4 = Q. | last5 = Boulfelfel | first5 = S. E. | last6 = Lyakhov | first6 = A. O. | last7 = Stavrou | first7 = E. | last8 = Somayazulu | first8 = M. | last9 = Prakapenka | first9 = V. B. | last10 = Konôpková | first10 = Z. | doi = 10.1126/science.1244989 | title = Unexpected Stable Stoichiometries of Sodium Chlorides | journal = Science | volume = 342 | issue = 6165 | pages = 1502–1505 | year = 2013 | pmid =  24357316|arxiv = 1310.7674 |bibcode = 2013Sci...342.1502Z | s2cid = 15298372 }}</ref>

== See also ==
* {{Annotated link|Antimatter}}
* {{Annotated link|Dark energy}}
* {{Annotated link|Dark matter}}
* {{Annotated link|Gravitational interaction of antimatter}}
* {{Annotated link|Mirror matter}}
* {{Annotated link|Negative energy}}
* {{Annotated link|Negative mass}}
* {{Annotated link|QCD matter}}
* {{Annotated link|Strange matter}}

== References ==
{{Reflist|30em}}

==External links==
{{Commons category}}
*{{YouTube|lzoYmLTrQ_8|Exotic Matter and Negative Energy}}
*{{YouTube|Y5oNwJNdMxY|The Riddle of AntiMatter}}

{{Particles}}
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[[Category:Exotic matter| ]]
[[Category:Hypothetical particles]]
[[Category:Gravity]]
[[Category:Wormhole theory]]
[[Category:Warp drive theory]]