Dark energy star
Encyclopedia
A dark-energy star is a hypothetical compact astrophysical object, which a minority of physicists feel might constitute an alternative explanation for observations of astronomical black hole
candidates. Dark energy is invisible to the human eye; however, it can be tracked with difficulty by gamma-ray astronomy
.
The concept was proposed by physicist
George Chapline. The theory states that infalling matter is converted into vacuum energy or dark energy, as the matter falls through the event horizon
. The space within the event horizon would end up with a large value for the cosmological constant
and have negative pressure to exert against gravity. There would be no information-destroying singularity
.
George Chapline claimed that quantum mechanics
makes it a "near certainty" that black holes do not exist and are instead dark-energy stars. The dark-energy star is a different concept than that of a gravastar
.
Dark-energy stars were first proposed because in quantum physics, absolute time is required; however, in general relativity
, an object falling towards a black hole would to an outside observer seem to have time pass infinitely slowly at the event horizon
. The object itself would feel as if time flowed normally.
In order to reconcile quantum mechanics
with black holes, Chapline theorized that a phase transition in the phase of space occurs at the event horizon. He based his ideas on the physics of superfluids. As a column of superfluid
grows taller, at some point, density increases, slowing down the speed of sound, so that it approaches zero. However, at that point, quantum physics makes sound waves dissipate their energy into the superfluid, so that the zero sound speed condition is never encountered.
In the dark-energy star hypothesis, infalling matter approaching the event horizon decay into successively lighter particles. Nearing the event horizon, environmental effects accelerate proton decay
. This may account for high energy cosmic ray sources and positron sources in the sky. When the matter falls through the event horizon, the energy equivalent of some or all of that matter is converted into dark energy
. This negative pressure
counteracts the mass the star gains, avoiding a singularity. The negative pressure also gives a very high number for the cosmological constant
.
Furthermore, 'primordial' dark-energy stars could form by fluctuations of space-time itself, which is analogous to "blobs of liquid condensing spontaneously out of a cooling gas." This not only alters the understanding of black holes, but has the potential to explain the dark energy
and dark matter
, that are indirectly observed.
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...
candidates. Dark energy is invisible to the human eye; however, it can be tracked with difficulty by gamma-ray astronomy
Gamma-ray astronomy
Gamma-ray astronomy is the astronomical study of the cosmos with gamma rays. Gamma-rays are the most energetic form of "light" that travel across the universe, and gamma-rays thus have the smallest wavelength of any wave in the electromagnetic spectrum.Gamma-rays are created by celestial events...
.
The concept was proposed by physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
George Chapline. The theory states that infalling matter is converted into vacuum energy or dark energy, as the matter falls through the event horizon
Event horizon
In general relativity, an event horizon is a boundary in spacetime beyond which events cannot affect an outside observer. In layman's terms it is defined as "the point of no return" i.e. the point at which the gravitational pull becomes so great as to make escape impossible. The most common case...
. The space within the event horizon would end up with a large value for the cosmological constant
Cosmological constant
In physical cosmology, the cosmological constant was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe...
and have negative pressure to exert against gravity. There would be no information-destroying singularity
Gravitational singularity
A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system...
.
Theory
In March 2005, physicistPhysicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
George Chapline claimed that quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
makes it a "near certainty" that black holes do not exist and are instead dark-energy stars. The dark-energy star is a different concept than that of a gravastar
Gravastar
A gravastar is an object hypothesized in astrophysics as an alternative to the black hole theory by Pawel Mazur and Emil Mottola. It results from assuming real, physical limitations on the formation of black holes...
.
Dark-energy stars were first proposed because in quantum physics, absolute time is required; however, in general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
, an object falling towards a black hole would to an outside observer seem to have time pass infinitely slowly at the event horizon
Event horizon
In general relativity, an event horizon is a boundary in spacetime beyond which events cannot affect an outside observer. In layman's terms it is defined as "the point of no return" i.e. the point at which the gravitational pull becomes so great as to make escape impossible. The most common case...
. The object itself would feel as if time flowed normally.
In order to reconcile quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
with black holes, Chapline theorized that a phase transition in the phase of space occurs at the event horizon. He based his ideas on the physics of superfluids. As a column of superfluid
Superfluid
Superfluidity is a state of matter in which the matter behaves like a fluid without viscosity and with extremely high thermal conductivity. The substance, which appears to be a normal liquid, will flow without friction past any surface, which allows it to continue to circulate over obstructions and...
grows taller, at some point, density increases, slowing down the speed of sound, so that it approaches zero. However, at that point, quantum physics makes sound waves dissipate their energy into the superfluid, so that the zero sound speed condition is never encountered.
In the dark-energy star hypothesis, infalling matter approaching the event horizon decay into successively lighter particles. Nearing the event horizon, environmental effects accelerate proton decay
Proton decay
In particle physics, proton decay is a hypothetical form of radioactive decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron...
. This may account for high energy cosmic ray sources and positron sources in the sky. When the matter falls through the event horizon, the energy equivalent of some or all of that matter is converted into dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...
. This negative pressure
Negative pressure
Negative pressure may refer to:*negative pressure as opposed to positive pressure*stretched liquid*vacuum*negative gauge pressure, a way of expressing pressure measurements below atmospheric pressure*suction*transpirational pull...
counteracts the mass the star gains, avoiding a singularity. The negative pressure also gives a very high number for the cosmological constant
Cosmological constant
In physical cosmology, the cosmological constant was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe...
.
Furthermore, 'primordial' dark-energy stars could form by fluctuations of space-time itself, which is analogous to "blobs of liquid condensing spontaneously out of a cooling gas." This not only alters the understanding of black holes, but has the potential to explain the dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...
and dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
, that are indirectly observed.
External links
- MPIE Galactic Center Research (subscription only)