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- We cannot see a blackhole by definition no light will ever reach us. But, can we see a Blackhole’s shadow, a black silhouette against a backdrop of hot glowing gas? Maybe?
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- So far, what astronomers have detected is a black spot in the sky that is so massive and is in such a tiny area according to the General Theory of Relativity it “must” be a blackhole.
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- In the theory blackholes are characterized by only three attributes: mass, charge, and spin.
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- Astronomers can see the in flowing material before it passes the event horizon of the blackhole. The energy at the horizon produces heat 20 times more efficiently than nuclear fusion. The environment near a blackhole is the brightest object in the universe. Ironically!
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- The best blackhole to observe is the one at the center of our Milky Way Galaxy. Called Sagittarius A*it is just 26,400 light-years away. The horizon’s diameter for this 4,300,000 Solar Mass blackhole is only 55 micro-arc-seconds wide.
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- This would be like trying to see a poppy seed in Los Angeles viewed from the Empire State building in New York City.
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- As impossible as this sounds radio telescopes located 5,000 kilometers apart acting as a giant interferometer can resolve down to 100 microseconds. That is only double what we need. The radio wavelengths are 3.5 millimeters. And these wavelengths get blurred by the interstellar gas. So radio astronomy gets close but not close enough to see what they want.
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- Astronomers would love to use infrared telescopes. The shorter wavelengths pass through the dust clouds that hide Sagittarius A*. However, to get an angular scale of 55 micro- arc- seconds the telescope would have to be 7 kilometers in diameter. That is a big infrared telescope.
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- If we go to millimeter radio waves the telescope would need to be 5,000 kilometers in diameter, about the size of the Earth. We have radio telescopes all over the planet. If we could tie them together as a single interferometer the needed angular resolution could be achieved.
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- There are two very Long Baseline Telescope Arrays in operation today, but, they are limited to the wavelengths above 3.5 millimeters, which corresponds to 100 micro- arcs- seconds resolution.
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- We need a global interferometer operating at shorter wavelengths, 1.3 millimeters would allow 26 micro -arc- seconds resolution.
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- A blackhole swallows light coming towards the observer from just behind it. The light bends back on itself and wraps around the blackhole. Strong gravitational lensing bends the light from behind resulting in a silhouette. The silhouette will not be circular because of the fast-moving gas rotating around the blackhole. This silhouette will allow astronomers to measure the spin and the inclination of the accretion disk.
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- Sagittarius A*is not the only target for this millimeter interferometer telescope. M87 is a giant elliptical galaxy 55,000,000 light-years away. It's mass is 6,600,000,000 solar mass. It is spouting a jet of material out its poles extending 5,000 light-years across.
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- M87 is 2,000 times larger than Sagittarius A*. The orbital period of the inner edge of its accretion disk is 0.5 to 5 weeks, depending on the spin rate.
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- Astronomers hope to get lucky and observe a bright spot flare up in the accretion disk. Gravitational lensing will produce multiple images of this spot. Analysis will provide detailed information about the gravitational field around the blackhole. Astronomers will use the equations from the General Theory of Relativity to see how well the math matches observation.
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- We think the massive object at the center of our galaxy is a blackhole, but, could it just be a black star?
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- We also think massive stars will collapse into smaller blackholes. A blackhole 3 solar mass would have a diameter of 11 miles.
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- The diameter we refer to is the event horizon where curve space-time is so intense due to gravity that even light folds back on itself. Nothing can escape. Everything falls back to a point where matter density approaches infinity.
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- That is theory. What about observation? Astronomers have discovered many locations where dark objects have masses ranging from 3 to 1,000,000 solar mass. The diameter of these dark objects ranges from several miles to 620,000 miles.
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- The math of General Relativity gets us to a point, but, infinities rule out the math working further. Near the microscopic scale Quantum effects requires different math. Unfortunately, this math reduces to the energy of a vacuum being infinite as well.
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- General Relativity and Quantum Mechanics can not deal with infinities that rise with modeling a blackhole. Maybe Quantum Mechanics effects cancel General relativity effects and a blackhole does not form
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- Quantum field Theory describes each fundamental particle as a “field” that is flat. If matter is present the gravity is present and spacetime is curved.
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- The math says that a solar mass blackhole that is not rotating and not electrically charged has a radius of 3 kilometers (1.86 miles).
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- The Sun is 435,000 mile radius. To be a blackhole it would need to be 1.86 miles diameter. Its temperature would be 60 nano-Kelvin. This slight temperature is called “Hawking radiation”. This small amount of radiation would cause the blackhole to eventually evaporate into outer space.
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- A large star is composed of 10^55 particles. A blackhole becomes hotter and evaporation faster as its mass and radius shrink. After all evaporates , or , explodes , what happens to the information? When the encyclopedia burns up does the information still reside in the smoke and ashes? This is a question for Richard Feynman, not me.
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- If Quantum effects do counterbalance the pull of gravity then maybe a small high density Black Star does form instead of a Blackhole. Black Stars would be material bodies with a surface and an interior of dense matter. A Black Star has no event horizon. It retains all the information that existed before the its collapse. An announcement will be made shortly, stay tuned.
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RSVP, with comments, suggestions, corrections. An index of reviews is available. Some reviews are at: -------------------- http://jdetrick.blogspot.com -----------
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