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---------------------- 2338 - Blackhole - how to take the first picture?
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- Albert Einstein’s theory of General Relativity predicted that blackholes should exist over 100 years ago. It was not until the 1960’s that physicist John Wheeler first coined the name ‘blackhole’.
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- Theoretical physics could identify certain astronomical phenomena such as quasars and x-ray sources where there was simply no other explanation for how such phenomena could generate so much energy in such an impossibly small volume of space.
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- These explanations remained theories until the 1990s when studies of distant galaxies by the Hubble Space Telescope returned the data that clinched the idea that the cores of most if not all galaxies had a massive Blackhole.
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- These blackholes contained millions or even billions of times the mass pf the Sun. But, not a single one had ever been “seen“.
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- General relativity is the preeminent theory of gravity, but it is completely couched in the language of geometry called our 4-dimensional space-time continuum. The problems in the math occur when you collect enough mass together in a small enough volume of space the geometry of spacetime created by the strength of gravity becomes enormously curved.
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- The very first thing that happens according to the theory is that a condition in spacetime called a Singularity forms. Here, general relativity itself falls apart because density and gravity tend towards infinite conditions. The math no longer works
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- Spacetime immediately develops a zone surrounding the Singularity called an event horizon. For blackholes more massive than our Sun, the distance in kilometers of this spherical horizon from the Singularity is just 2.9 times the mass of the blackhole in multiples of the Sun’s mass.
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- For example, if the mass of a supermassive black hole is 6.5 billion times the mass of our Sun, its event horizon is at 6.5 billion times 2.9 = 19 billion kilometers. Our solar system has a radius of only 8 billion kilometers out to Pluto, so this supermassive black hole is over twice the size of our solar system!
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- Now the problem with event horizons is that they are one-way. Objects and even light can travel through them from outside the blackhole, but once inside they can never return to the outside universe to give a description of what happened. No light can escape.
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- The astrophysicist have never been able to take a look at what is going on around the event horizon until April 10, 2019.
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- Researchers using the radio telescope interferometer system called the Event Horizon Telescope were able to synthesize an image of the surroundings of the supermassive blackhole in the quasar-like galaxy Messier-87. This quasar was located by radio astronomers after World War II about 55 million light years from Earth.
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- Today’s astronomers have combined the data from eight radio telescopes scattered around the globe from Antarctica to the UK to create one telescope with the effective diameter of the entire Earth.
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- Astronomers were able to detect and resolve details at the center of M-87 near the location of a presumed supermassive blackhole. This blackhole is surrounded by a swirling disk of magnetized matter, which ejects a powerful beam of plasma into intergalactic space. It has been intensively studied for decades and the details of this process always point to a supermassive blackhole as the cause.
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- Beginning in 2016, several petabytes of data were gathered from the Event Horizon Telescope and the first images of the vicinity of the event horizon were published. Surrounding the black shadow zone containing the event horizon was a clockwise-rotating ring of billion-degree plasma traveling at nearly the speed of light.
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- When the details of this image were compared with supercomputer simulations, the mass of the supermassive blackhole could be accurately determined as well as the dynamics of the ring plasma. The round shape of the event horizon was not perfect, which means that it is a rotating blackhole.
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- The darkness of the zone indicated that the event horizon did not have a photosphere of hot matter like the surface of our sun, so many competing ideas about this mass could be eliminated. Only the blackness of a blackhole and its compact size now remain as the most consistent explanation for what we are ‘seeing’. Over time, astronomers will watch as this ring plasma moves from week to week.
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- The next target for the Event Horizon Telescope is the four million solar mass blackhole at the center of the Milky Way called Sagittarius -A*.
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- We have entered a new world in exploring our universe.
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- April 23, 2019
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-------------------------- Tuesday, April 23, 2019 --------------------------
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