There is nothing like a true black hole| Dr. Abhas Kumar Mitra.

Black holes are known to majority of people. Each individual gets really fascinated upon thinking about what lies inside this black giant. We know that we cannot see black holes since they reflect no light, but scientists have been trying to detect them by studying the behavior of the objects around them. On 10^th April, 2019, scientists revealed the first ever image of a black hole.

BLACK HOLE

But was it really a picture of a true black hole? 

An Indian Astrophysicist, DR. Abhas Kumar Mitra, said that the objects which we assume to be black holes are actually Eternally Collapsing Objects (ECO). His theory was in limelight for a while, but it was soon dismissed, but not wholly. 

Following him, several other scientists also tried to research more about ECO. Darryl Leiter and Stanley Robertson were one of them. They modified the name ECO to Magnetospheric Eternally Collapsing Objects (MECO). 

So, let us start unleashing the secrets of ECO and how it is different from a theoretical black hole. Before that please visit the link below to get a quick glimpse over the life cycle of a star and if you are aware of it, then you are welcome to unleash the secrets!

The life cycle of a star

ETERNALLY COLLAPSING OBJECTS.

This is how an ECO must look like

An ECO is formed just like a black hole is formed, i.e. it is also formed after a supernova explosion of an extremely giant star.

They do not have the event horizon. They appear like a hot glowing body, just like the Sun, but its temperature is far greater than a star. 

They have a very strong magnetic field of their own. They can be called quasi-black holes because they are not the true black holes but are on their way to become one. 

WHY ARE THEY CALLED ECO?

The singularity of a black hole is formed in a finite time after the supernova explosion, but in ECO, after the explosion, formation of singularity takes infinite time.

REASON-

A supernova explosion

After the explosion, the star starts to collapse under its own weight and the core becomes very hot and dense due to contraction and therefore, the core starts to shine very brightly.

But even there is a limit, it's Eddington limit (The maximum luminosity of a star) , once a star reaches this limit, the contraction gets countered by an outward force. This outward push is nothing but the energy produced in the hot core.

But this does not mean that the contraction has stopped, this only means that the contraction has become a very gradual process. Thus this core collapses under its weight forever. Therefore its name is Eternally Collapsing Objects.

They are also called Extremely hot and Relativistic Radiation supported stars. This is because the energy coming out of their core as radiations slows down the process of contraction. This process of contraction and emission of radiation is continuous.

THE CONCEPT BEHIND ECO.

WHY CANT A STAR COLLAPSE TO FORM SINGULARITY?

SOURCE

According to general relativity, time dilation occurs around the objects with gravity near to infinity. But it also says that space time is not constant, but it is relative.  

If a star is ready to form a singularity, its gravitational force will become infinity and thus this will cause time dilation. But one cannot be sure if this theory of formation of singularity is correct or not from their frame of reference.

Even many renowned scientists agreed with the fact that a star cannot collapse to form a single point because there is a certain limit, that limit is the Schwarzschild radius. According to them, although mathematics can go inside that radius, but the space inside that radius is not a physical region, it belongs to a different universe. An ECO has a radius which is just a little more than its Schwarzschild radius.

Schwarzschild radius of a black hole

But still, the concept of a true black hole was widely accepted by everyone because of two reasons, but yet no one bothered to look at the flaws of these two proofs of existence of a black hole. 

The two proofs with there are explained in detail in the following –

  

     1.    Proof- Two American physicists showed with the help of dust that a star, after the explosion, went through a collapse under a finite time and formed a singularity and an invisible event horizon.

Dust cloud, located about 6,000 light-years away in the constellation Sagittarius

Flaw- They represented it through dust and this state of matter has no pressure of its own.

      2.    Proof-An esteemed mathematical physicist, while doing his research about the gravitational collapse of a star, assumed that if a star starts to collapse, there will be formation of an invisible one way trap door. This assumption was very similar to the event horizon. Due to this assumption, he was able to present a mathematical proof of the formation of singularity.

Flaw- He was not able to explain that why that trap door was formed.

You would ask that how can any object collapse into itself forever? I mean, we cannot even think to do that! Well, for us it will be nearly impossible because we do not warp space-time at that extent.

Let me explain it to you. If the gravitational force increases of any object, it will sink more into space-time. If you still did not understand it, then look at the image below.

Space time warpped around earth. This curvature of space time is only the gravity.

Thus an ECO has the ability to sink more and more into the space time as its gravitational force increases.

If you have not yet understood the difference between these two objects, then let us understand the following points.

DIFFERENCES.

     1.    ECOs are quasi black holes, i.e. they are not the true black holes.

     2.    Since ECOs are radiation supported stars, they have a physical surface made up of hot plasma, but black holes do not have any physical surface.

3.    Unlike black holes, ECOs do not have an event horizon.

     4.    1 out of every 1 million photons, can escape the surface of an ECO, since its gravity is not infinity, but to a distant observer, an ECO would appear to be black, but nothing can escape a black hole.

 5.    Unlike Black holes, the laws of physics do not break down in ECOs.

    6.    ECOs have a very strong magnetic fields, but a black hole can either have a very weak magnetic field (rotating black holes)or no field at all (static black holes).

I know that a question is continuously wandering in your head, “Is there any evidence of presence of an ECO/MECO?”

EVIDENCES OF AN ECO.

1.In 2006, a quasar (The most luminous objects in the universe) was observed which was approximately 9 billion light years away from earth. Actually, whenever an object is about to enter a black hole, it starts to revolve around it at a very high speed. This causes production of heat and thus this causes a luminous glow. We even know that an ECO has also a very strong magnetic field. Since, the observed quasar had a very strong magnetic field of its own; it provided a strong evidence for ECO.

An artistic impression as how a quasar looks

2.The detection of gravitational waves provide an evidence of black holes, but these waves are also accompanied by unknown noise signals and we very well know that even sound waves need a surface to get reflected and the space near a black hole is vacuum. But an ECO has a physical surface. This is also an evidence of ECO.

n this artist’s conception, a binary black hole produces gravitational waves that travel outwards and carry energy away from the system.

3. In theory, a true black hole has no mass. (It must be noted that here ‘no mass’ does not mean an absence of matter. In general relativity it simply means the total sum of the energies around that body and negative self-gravitational energy of that body, i.e. the self-gravitational energy of a star so strong that it can counter the other energies around it.)
 

But, in observation, black holes with finite masses were only detected. 

WHY IS THIS THEROY STILL NOT ACCEPTED?

Many scientists support this theory given by Dr. Abhas Mitra, but still it is not accepted because majority of scientists believe that it is not an alternative to black holes. 

I mean to say that, even an ECO is on its way to attain the state of singularity, although the process is eternal. Hence, the conclusion will be the same.

Black holes are really interesting, but the theory of ECO/MECO is not less interesting. I hope that very soon in the future, this theory will again come into limelight and will be under a serious consideration.