Magnetospheric eternally collapsing object
Encyclopedia
Magnetospheric Eternally Collapsing Objects or MECOs are proposed alternatives to black hole
s advocated by Darryl Leiter and Stanley Robertson. They are a variant of eternally collapsing objects or ECOs proposed by Abhas Mitra
in 1998. Mitra had devised an ostensive proof that black holes cannot form from the spherically symmetric gravitational collapse
of a star. Based on this, he argued that the collapse must be slowed to a near halt by radiation pressure
. A proposed observable difference between MECOs and black holes is that the MECO can produce its own magnetic field
. An uncharged black hole cannot produce its own magnetic field, but its accretion disc
can. Astronomer Rudolph Schild claims to have found evidence of such a magnetic field from the black hole candidate in the quasar
Q0957+561
.
Neither ECOs nor MECOs have gained any significant acceptance among scientists; Gerry Gilmore of the Institute for Astronomy at the University of Cambridge
has stated that the concept is "almost certainly wrong," and the mathematician Chris Hillman has stated that it is "flat out wrong". Mitra's proof that black holes cannot form is based on the argument that in order for a black hole to form, the collapsing matter must travel faster than the speed of light with respect to a fixed observer. Paulo Crawford and Ismael Tereno have cited this as an example of a "wrong and widespread view," and explain that in order for a frame of reference
to be valid, the observer must be moving along a timelike worldline. At or inside the event horizon
of a black hole, it is not possible for such an observer to remain fixed; all observers are drawn toward the black hole.
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...
s advocated by Darryl Leiter and Stanley Robertson. They are a variant of eternally collapsing objects or ECOs proposed by Abhas Mitra
Abhas Mitra
Abhas Mitra is an Indian astrophysicist who is head of the Theoretical Astrophysics Section at the Bhabha Atomic Research Centre.Mitra's writings challenging accepted ideas about black holes have led to him being described as an "anti-black hole astrophysicist" by Nature. He uses the term eternally...
in 1998. Mitra had devised an ostensive proof that black holes cannot form from the spherically symmetric gravitational collapse
Gravitational collapse
Gravitational collapse is the inward fall of a body due to the influence of its own gravity. In any stable body, this gravitational force is counterbalanced by the internal pressure of the body, in the opposite direction to the force of gravity...
of a star. Based on this, he argued that the collapse must be slowed to a near halt by radiation pressure
Radiation pressure
Radiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. If absorbed, the pressure is the power flux density divided by the speed of light...
. A proposed observable difference between MECOs and black holes is that the MECO can produce its own magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
. An uncharged black hole cannot produce its own magnetic field, but its accretion disc
Accretion disc
An accretion disc is a structure formed by diffuse material in orbital motion around a central body. The central body is typically a star. Gravity causes material in the disc to spiral inward towards the central body. Gravitational forces compress the material causing the emission of...
can. Astronomer Rudolph Schild claims to have found evidence of such a magnetic field from the black hole candidate in the quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
Q0957+561
Twin Quasar
The Twin Quasar , also known as SBS 0957+561, or TXS 0957+561 , was the first identified gravitationally lensed object.-Quasar:...
.
Neither ECOs nor MECOs have gained any significant acceptance among scientists; Gerry Gilmore of the Institute for Astronomy at the University of Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
has stated that the concept is "almost certainly wrong," and the mathematician Chris Hillman has stated that it is "flat out wrong". Mitra's proof that black holes cannot form is based on the argument that in order for a black hole to form, the collapsing matter must travel faster than the speed of light with respect to a fixed observer. Paulo Crawford and Ismael Tereno have cited this as an example of a "wrong and widespread view," and explain that in order for a frame of reference
Frame of reference
A frame of reference in physics, may refer to a coordinate system or set of axes within which to measure the position, orientation, and other properties of objects in it, or it may refer to an observational reference frame tied to the state of motion of an observer.It may also refer to both an...
to be valid, the observer must be moving along a timelike worldline. At or inside 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...
of a black hole, it is not possible for such an observer to remain fixed; all observers are drawn toward the black hole.