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Singularity, the Event Horizon, Donuts and Falling into a Black Hole

Image: NASA Artist’s conception of a black hole with plasma jets and accretion disk

Some stars die in massive implosions that only stabilize with the creation of a ’singularity’ – often a supernova, or super star implosion/explosion – which throws vast quantities of dust, gas and radiation at several wavelengths into the universe. The spectral pattern across the radiation spectrum is distinctive and sometimes meets the requirements for the signature of a black hole. Radiation, including visible light, that is captured by a black hole cannot escape and astronomers cannot ’see’ a black hole at any wavelength. The boundary beyond which all matter is sucked into the black hole and can never escape is the ‘event horizon’. Astronomers can see and study what happens to gas and radiation at the event horizon immediately before the material is drawn into the black hole by its immense gravitational force. Radiation is emitted at several wavelengths and objects can orbit a black hole indefinitely at the event horizon. Einstein had predicted the existence of black holes, and spectral analysis of the radiation released by the violent activity just outside the event horizon led astronomers to the discovery of the spectral pattern that identifies real black holes in our real universe. A complicated analysis of gas spirals as they fall inward towards the event horizon revealed X-ray emission whose intensity varies over a regular repeating pattern. This Quasi-Periodic Oscillation depends on the mass of the black hole. The higher the QPO frequency, the closer the event horizon is to a black hole. Small black holes have close-in event horizons and high QPO. Large black holes have event horizons further out and lower QPO frequency.

Supermassive Black Hole

Image: Harvard University

We will never see black holes directly, but we can determine where they live, their coordinates and much of what they do. The very low thermal radiation predicted by Stephen Hawking to be emitted by black holes is controversial and has never been confirmed. The black hole itself, invisible except for the atomic radiation events just outside its edge, possesses massive gravity whose strength has no equal anywhere in the universe. A black hole is a ’singularity’, which in the specialized vocabulary of atomic physics and quantum dynamics means that the laws of physics as we know them in the visible universe do not apply. What does apply is only beginning to be understood because black holes have infinite mass, but no volume and no dimensions. Furthermore, black holes are surrounded by a region of space-time (the true 4th dimension) called the ergosphere in which it is impossible to stand still. Research announced in December, 2008 confirmed that black holes and the material just outside the event horizon can be pictured as a donut. A comprehensive study was made of the centers of 245 galaxies that are powered by disks of hot material feeding a super-massive black hole. Results revealed an ordered physical structure shaped like a donut that is independent of the black hole’s size. The black hole itself, of course, is the hole in the donut.

Black Hole – Ergosphere

Image: Wikipedia

Let’s talk about falling into a black hole – something to be avoided at all costs. A black hole’s gravity is so strong, it can pull objects apart at the atomic level when they are just inside the event horizon. Hadrons in the nucleus will be torn apart into their constituent quarks. The process is called spaghettification – although no one predicts the creation of pasta shaped objects. Spaghettification is odd because how gravity interacts over distance is the defining parameter not the absolute strength of the gravitational field. Small black holes have the greatest capacity to tear objects apart while objects falling into massive black holes might remain largely intact.

Imagine we are close to a black hole, our space ship has stopped not far from the event horizon of a black hole and we are watching a planet with intelligent life and civilizations that has been captured by the immense gravity of a black hole. Before the planet crosses the event horizon, it experiences time dilation – the slowing down of time – relative to those of us beyond the gravitational field of the black hole and outside the event horizon . As we watch, all active processes on the planet seem to be slowing down as it approaches the event horizon. Gravitational time dilation will approach infinity for the falling planet as it travels closer and closer to the event horizon. When it is very close to the event horizon, we notice that the planet appears red because as objects approach the speed of light, their visible light spectrum shifts towards red wavelengths. The planet is also becoming very faint and difficult to see. At a point just before the event horizon, it ‘disappears’. Faint red light carries very little energy because the frequency of light now completes fewer cycle per ‘tick’ of the clocks we watch as outside observers. However, from the viewpoint of those on the planet falling into the black hole, we appear blue because distant objects as viewed from this planet inside the event horizon appear blue-shifted.

To those of us watching outside the event horizon, it appears to take an infinite amount of time for the planet to cross the event horizon. To those on the planet, at first there is nothing unusual that can be seen or heard and objects outside the event horizon are still visible. When it is very close to the black hole singularity, everything on this captured planet is torn apart down to the atomic level where subatomic particles are ripped away from one another. Once inside the black hole – in the singularity – we have almost no ideas and no good theories for what happens.

Black Hole disrupts and swallows nearby star

Image: Harvard University

The History of the Black Hole >

Tiny Black Holes that Devour Stuff!>

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