In physics, exotic matter is matter that somehow deviates from normal matter and has "exotic"
properties. A broader definition of exotic matter is any kind of non-baryonic matter—that
is not made of baryons, the subatomic particles (such as protons and neutrons) of which ordinary
matter is composed. Exotic mass has been considered a colloquial term for matters such as dark
matter, negative mass, or complex mass.
== Types of exotic matter == There are several types of exotic matter:
Hypothetical particles and states of matter that have "exotic" physical properties that
would violate known laws of physics, such as a particle having a negative mass.
Hypothetical particles 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 hadrons and within the Standard Model.
States of matter that are not commonly encountered, such as Bose–Einstein condensates, fermionic
condensates, quantum spin liquid, string-net liquid, supercritical fluid, color-glass condensate,
quark–gluon plasma, Rydberg matter, Rydberg polaron and photonic matter but whose properties
are entirely within the realm of mainstream physics.
States of matter that are poorly understood, such as Dark matter and Mirror matter.
Ordinary matter placed under high pressure, which may result in dramatic changes in its
physical or chemical properties. Degenerate matter
Exotic atoms
== 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 energy. It is used in certain speculative theories, such as on the construction
of artificial wormholes and the Alcubierre drive. The closest known real representative
of such exotic matter is the region of pseudo-negative-pressure density produced by the Casimir effect.
According to mass–energy equivalence, mass
m
is in proportion to energy
E
and the coefficient of proportionality is
c
2
{\displaystyle c^{2}} . Actually,
m
is still equivalent to
E
although the coefficient is another constant
such as
−
c
2
{\displaystyle -c^{2}} . In this case, it is unnecessary to introduce
a negative energy because the mass can be negative although the energy is positive.
That is to say,
E =
− m
c
2
> 0
{\displaystyle E=-mc^{2}>0}
m =
−
E
c
2
< 0
{\displaystyle m=-{\frac {E}{c^{2}}}<0} Under the circumstances，
d E
= F
d s
=
d p
d t
d s
=
d s
d t
d p
= v
d p
= v
d (
m v
)
{\displaystyle dE=Fds={\frac {dp}{dt}}ds={\frac {ds}{dt}}dp=vdp=vd(mv)}
−
c
2
d m
= v
d (
m v
)
{\displaystyle -c^{2}dm=vd(mv)}
−
c
2
( 2
m )
d m
= 2
m v
d (
m v
)
{\displaystyle -c^{2}(2m)dm=2mvd(mv)}
−
c
2
d (
m
2
) =
d (
m
2
v
2
)
{\displaystyle -c^{2}d(m^{2})=d(m^{2}v^{2})}
−
m
2
c
2
=
m
2
v
2
+ C
{\displaystyle -m^{2}c^{2}=m^{2}v^{2}+C} When
v =
0
,
C =
−
m
0
2
c
2
{\displaystyle C=-m_{0}^{2}c^{2}} Consequently,
−
m
2
c
2
=
m
2
v
2
−
m
0
2
c
2
{\displaystyle -m^{2}c^{2}=m^{2}v^{2}-m_{0}^{2}c^{2}}
m =
m
0
1 +
v
2
c
2
{\displaystyle m={m_{0} \over {\sqrt {1+\displaystyle {v^{2} \over c^{2}}}}}}
where
m
0
< 0
{\displaystyle m_{0}<0} is invariant mass and invariant energy equals
E
0
= −
m
0
c
2
> 0
{\displaystyle E_{0}=-m_{0}c^{2}>0} . The squared mass is still positive and the
particle can be stable. Since
m =
m
0
1 +
v
2
c
2
< 0
{\displaystyle m={m_{0} \over {\sqrt {1+\displaystyle {v^{2} \over c^{2}}}}}<0}
,
p =
m v
=
m
0
v
1 +
v
2
c
2
< 0
{\displaystyle p=mv={m_{0}v \over {\sqrt {1+\displaystyle {v^{2} \over c^{2}}}}}<0}
The negative momentum is applied to explain negative refraction, inverse Doppler effect
and reverse Cherenkov effect observed in a negative index metamaterial. The radiation
pressure in the metamaterial is also negative because the force is defined as
F =
d p
d t
{\displaystyle F={\frac {dp}{dt}}} . Negative pressure exists in dark energy
too. Using these above equations, the energy-momentum relation should be
E
2
= −
p
2
c
2
+
m
0
2
c
4
{\displaystyle E^{2}=-p^{2}c^{2}+m_{0}^{2}c^{4}} Substituting the Planck-Einstein relation
E =
ℏ ω
and de Broglie's
p =
ℏ k
, we obtain the following dispersion relation
ω
2
= −
k
2
c
2
+
ω
p
2
{\displaystyle \omega ^{2}=-k^{2}c^{2}+\omega _{p}^{2}}
,
(
E
0
= ℏ
ω
p
= −
m
0
c
2
> 0
)
{\displaystyle (E_{0}=\hbar \omega _{p}=-m_{0}c^{2}>0)} of the wave consists of a stream of particles
whose energy-momentum relation is
E
2
= −
p
2
c
2
+
m
0
2
c
4
{\displaystyle E^{2}=-p^{2}c^{2}+m_{0}^{2}c^{4}} (wave–particle duality) can be excited in
a negative index metamaterial.The velocity of such a particle is equal to
v =
c
E
0
2
E
2
− 1
= c
ω
p
2
ω
2
− 1
{\displaystyle v=c{\sqrt {{\frac {E_{0}^{2}}{E^{2}}}-1}}=c{\sqrt {{\frac {\omega _{p}^{2}}{\omega ^{2}}}-1}}}
and range is from zero to infinity
ω
p
2
ω
2
< 2
{\displaystyle {\frac {\omega _{p}^{2}}{\omega ^{2}}}<2}
,
v <
c
ω
p
2
ω
2
> 2
{\displaystyle {\frac {\omega _{p}^{2}}{\omega ^{2}}}>2}
,
v >
c
Moreover, the kinetic energy is also negative
E
k
= E
−
E
0
= −
m
c
2
− (
−
m
0
c
2
) =
−
m
0
c
2
1 +
v
2
c
2
+
m
0
c
2
=
m
0
c
2
( 1
−
1
1 +
v
2
c
2
) <
0
{\displaystyle E_{k}=E-E_{0}=-mc^{2}-(-m_{0}c^{2})=-{m_{0}c^{2} \over {\sqrt {1+\displaystyle {v^{2} \over
c^{2}}}}}+m_{0}c^{2}=m_{0}c^{2}(1-{1 \over {\sqrt {1+\displaystyle {v^{2} \over c^{2}}}}})<0}
,
(
m
0
< 0
)
{\displaystyle (m_{0}<0)} In fact, the negative kinetic energy exists
in some models to describe dark energy (phantom energy) whose pressure is negative. In this
way, the negative mass of exotic matter is now associated with negative momentum, negative
pressure, negative kinetic energy and FTL (faster-than-light).
== Complex mass ==
A hypothetical particle with complex rest mass would always travel faster than the speed
of light. Such particles are called tachyons. There is no confirmed existence of tachyons.
E =
m ⋅
c
2
1 −
|
v
|
2
c
2
{\displaystyle E={\frac {m\cdot c^{2}}{\sqrt {1-{\frac {\left|\mathbf {v} \right|^{2}}{c^{2}}}}}}}
If the rest mass
m
is complex this implies that the denominator
is complex because the total energy is observable and thus must be real. Therefore, the quantity
under the square root must be negative, which can only happen if v is greater than c. As
noted by Gregory Benford et al., special relativity implies that tachyons, if they existed, could
be used to communicate backwards in time (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 Na3Cl and NaCl3. Quantum mechanical
calculations predict the possibility of other compounds, such as NaCl7, Na3Cl2 and Na2Cl.
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 cores. The materials have potentially useful properties. For instance, Na3Cl 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.
== See also == Antimatter – Material composed of the antiparticles
to the corresponding particles of ordinary matter
Dark energy – An unknown form of energy which is hypothesized to permeate all of space,
tending to accelerate the expansion of the universe
Dark matter – Hypothetical form of matter comprising most of the matter in the universe
Gravitational interaction of antimatter Mirror matter – A hypothetical counterpart
to ordinary matter Negative energy
Negative mass Strange matter
QCD matter – Theorized phases of matter whose degrees of freedom include quarks and
gluons