UPSC MAINS 2019 : First ever real image of a black hole revealed

black hole

 

First ever real image of a black hole revealed

Topic in Syllabus: General Studies Paper 3: Science & Technology

Context:

Recently the Event Horizon Telescope collaboration showed the world the ‘unseeable’: the very first image of a black hole.

black hole

More about on news:

  • The black hole itself cannot be seen, because light cannot escape its intense gravitational attraction.
  • The event horizon that envelops the black hole is the point of no return and any object transgressing this boundary is lost.
  • Just outside is a region where a photon (light quantum) can orbit the black hole without falling in.
  • This is called the ‘last photon ring’, and this is what the EHT imaged, seeing in effect the silhouette of a black hole.
  • The light that makes up the image is not coming from the black hole – black holes do not emit any light, hence the name.
  • Instead, the image shows the black hole’s silhouette against a background of hot, glowing matter that is being inexorably pulled in by its powerful gravity.
  • This image show the black hole in M87, which is 55 million light years away.

black holes

About Black Hole:

  • A Black Hole is a region of space which is of immense gravity that nothing—not even light—can escape from it.
  • Black holes form at the end of some stars’ lives, stars that are many times the mass of our sun.
  • The energy that held the star together disappears and it collapses in on itself producing a magnificent explosion.
  • All that material left over from the explosion falls into an infinitely small point.
  • Large black holes can have tens to millions of times the mass of our sun trapped in a point smaller than the tip of a pin.

 

Facts about Black hole:

  • Black holes are only dangerous if you get too close.
  • The nearest Black Hole is likely not 1,600 light-years away i.e 1.52 X 1012 Km approximately
  • There are at least three types of black holes, NASA says:
    • Primordial black holes are the smallest kinds, and range in size from one atom’s size to a
    • Stellar black holes, the most common type, are up to 20 times more massive than our own Sun.
    • Gargantuan ones in the centres of galaxies, called “supermassive black holes” each more than.

 

How Are Black Holes Made And What Causes A Black Hole?

  • Current theory suggests that small black holes (some as small as an atom but with the mass of a large mountain) probably formed in the earliest seconds of the universe.
  • Stellar black holes (about the mass of 20 of our suns plus) are created when massive stars collapse in on themselves. This process warps space-time during their death throws.
  • This happens during supernova events when massive stars explode incredibly violently.
  • Supermassive black holes (Roughly 1 million of our Sun’s mass plus) are thought to form as the galaxy they inhabit is formed.

tracing black hole image

More about on recent development:

  • A one-way boundary in space time surrounding a Black Hole.
  • In general relativity, an event horizon is a region in space-time beyond which events cannot affect an outside observer.
  • In layman’s terms, it is defined as the shell of “points of no return”, i.e., the boundary at which the gravitational pull of a massive object becomes as great as to make escape impossible.
  • The Event Horizon Telescope (EHT) operates a planet-scale array of eight ground-based radio telescopes that are linked together.
  • The EHT observations use a technique called very-long-baseline interferometry (VLBI) which synchronizes telescope facilities around the world and exploits the rotation of our planet to form one huge, earth-size telescope observing at a wavelength of 1.3mm.
  • VLBI allows the EHT to achieve an angular resolution of 20 micro-arc seconds, enough to read a newspaper in New York from a sidewalk cafe in Berlin.
  • The latest development confirmed that if immersed in a bright region, like a disc of glowing gas, scientists expect a Black Hole to create a dark region similar to a shadow — something predicted by Einstein’s general relativity that  never seen before.
  • The theory of general relativity predicts that the heated material will illuminate the extremely warped space-time, making a dark shadow visible.
  • This makes a confident ground for the scientists about the interpretation of their observations, including their estimation of the Black Hole’s mass.

 

Significance:

  • Images of the event horizon are particularly important when it comes to testing general relativity, which governs the behaviour of gravity and very large objects
  • it does not mesh with theories of quantum mechanics, which describes the very small, and the very edge of a supermassive black hole, where gravity is more intense than anywhere else we know of, is the best place to stress test that disconnect.
  • This is the first direct evidence that event horizons are actually real.
  • The event horizon is very tantalizing, because once something passes the event horizon it seems like can’t know anything about it
  • This first image is pushing back the limits of our knowledge.

 

Evolution of black hole:

  • About a hundred years ago, the black hole made its way into physics through Albert Einstein’s general theory of relativity.
  • Few years back from now, the LIGO collaboration first directly observed the gravitational waves made by the merging of two black holes.
  • After the LIGO collaboration first directly observed the gravitational waves made by the merging of two black holes, the ‘dark star’ had finally been imaged.
  • The Higgs boson was detected 50 years after it had been postulated, and gravitational waves were observed a century after Einstein predicted them.
  • Visual proof of the existence of black holes comes a century after they appeared in scientific literature. In a collaborative effort, eight telescopes around the world were used for the experiment.
  • The challenges included making each observe the same broad range of wavelengths around 1.3 mm and having precise atomic clocks at each location, so the data could be combined.
  • A black hole marks the end of spacetime as commonly understood, and nothing that enters it can escape from the tremendous gravitational attraction.

horizon telescope

About Event Horizon Telescope:

The Event Horizon Telescope (EHT) is a planet-scale array of eight ground-based radio telescopes forged through international collaboration. The EHT links telescopes around the globe to form an Earth-sized virtual telescope with unprecedented sensitivity and resolution.

Following Telescopes are part of it :

  • Atacama Large Millimeter Array
  • Atacama Pathfinder Experiment
  • Heinrich Hertz Submillimeter Telescope
  • IRAM 30m telescope
  • James Clerk Maxwell Telescope
  • Large Millimeter Telescope
  • South Pole Telescope
  • Sub-millimeter Array

What Is A Singularity?

singularity

  • A singularity or gravitational singularity is a point at the very center of a black hole.
  • It is a one-dimensional point that contains enormous amounts of mass in an infinitely small space.
  • Here gravity and density become infinite, space-time curves infinitely and the laws of known physics are thought to no longer apply.
  • Kip Thorne, the eminent American physicist, describes it as “the point where all laws of physics break down”
  • Current theory suggests that, as an object falls into a Black Hole and approaches the singularity at the centre, it will become stretched out or “spaghettified” due to the increasing differential in gravitational attraction on different parts of it, before presumably losing dimensionality completely and disappearing irrevocably into the singularity.

Way forward:

  • A black hole marks the end of space time as commonly understood, and nothing that enters it can escape from the tremendous gravitational attraction.
  • However, this is no real danger, as black holes are located at distances that humans do not have the power to scale.
  • The EHT set out to image two candidate supermassive black holes Sagittarius A*, which is 26,000 light years from the earth, at the centre of the Milky Way, and another which is 55 million light years away at the centre of the Messier 87 galaxy in the Virgo galaxy cluster.
  • The very long baseline interferometry technique linked radio dishes of telescopes across the world to produce a virtual telescope the size of the earth.
  • This was needed to obtain the high resolution required for this measurement.
  • Combining data from telescopes, each with different characteristics, was a separate challenge.
  • Cutting-edge developments from computer science related to image recognition were used.
  • The EHT succeed owing to interdisciplinary expertise that people bring to the table.
  • This experiment endorses the diversity of collaboration just as much as it does unrelenting patience and good faith in the power of science and reason.

 

Sample Question:

What do you mean by black hole? And “Discuss the significance of First Image of Blackhole”?


black hole infograph