Quasar, blackhole, singularity...?

Question

I'm reading a book called A short history of nearly everything by Bill Bryson, and all these things, Quasar, blackhole, singularity, fascinate me. Yet, I have no idea what they are.
Could you please explain these to me, their theories and their relationship with each other? what's a blackhole got to do with quasar... etc Thanks

Answer 1

The main hinge in the whole relation of all of these is gravity.
A quasar (QUAsi-StellAR object), is a highly-compacted, dead star...
It (at one point in its life) went nova (or supernova, I can't remember which, off the top of my head), and spun down to an incredibly dense core, consisting mainly of neutrons.
Quasars are neutron stars, spinning at a very high rate.
Black holes are the ultimate end of a massive star's life...
This star DID go supernova... and the remaining core spun down into itself gravitationally.
The spinning core was SO massive, it drew (and continues to draw), everything around it into a 'death spiral', where no matter within its gravitational grasp can escape, not even light, itself.
The 'singularity', as it has been hypothesized, is a point at the center of this nasty gravitational field.
It is to this point, smaller than the period at the end of this sentence, that all drawn- in matter falls.
Whoa!

Answer 2

Singularity: a point where an equation cannot be solved. for example, in y = 1 / (x-1), the point x=1 is a singularity.
In space, any zero volume object with mass would be a singularity because any calculation involving that object (e.g., surface gravity) cannot be solved (the solution is boundless).

Escape speed is the speed needed to be able to leave an object. For example, an object shot from Earth at more than 11.2 km/s will never fall back nor remain in orbit around Earth. It is able to go elsewhere in the universe.

For the Sun, escape speed is 617.5. Escape speed depends on the mass of the body (more mass = more speed needed to escape) and on its radius (same mass with smaller radius = more speed needed).

If you could squeeze the mass of the Sun into a radius less than 3 km, the escape speed would be more than 300,000 km/s. Since that is the speed of light, it means that even light cannot escape. Hence the name: black hole.

It is thought by cosmologists that once a mass becomes a black hole, all matter will be inexorably pulled towards the centre, with nothing being able to stop it (even elementary sub-particles and building blocks, like quarks, will not resist the pressure). The matter will form a singularity.

However, at the distance from the centre where the escape speed is the speed of light, there is the event horizon. It is impossible for us to see deeper into the black hole. We are therefore shielded from ever seeing the singularity. However, some cosmologists believe that under special conditions (extremely rapidly rotating black hole) it could be possible that the matter (in a singularity ring) could exist outside the event horizon, giving us a "naked singularity". The effects on the universe would not be very good (and most cosmologists still believe that all singularities are shielded and non-shielded singularities cannot be.

When matter falls towards a black hole, it will be torn apart (tidal effects) before reaching the event horizon. Because the black hole is relatively small (on a universal scale) and becasue any matter has some random movement vector, matter does not fall directly into the black hole. It will form an accretion disk that orbits the black hole.

Because of the release of energy (tidal effects and friction), the orbit of each particle in the disk decays. Sub atomic particles separate and you have charged particles turning very rapidly around the black hole, creating strong magnetic field. Plasma is ejected in two cones, perpendicular to the accretion disk.

These plasma jets interact with other matter around them and can create radio signals or visible light (or even X-rays).

If the black hole is located at the centre of a galaxy (most galaxies do have a central black hole), there is lots of other matter with which the jets can interact. In some cases, the jets carry so much energy that the resulting light, all coming from the central region (a very small core), outshines the entire galaxy. This is a quasar.

Answer 3

I'll try part of this. When a star converts all its hydrogen to helium, it is in trouble. An astrophysicist name Chandrasekar theorized that a star with a helium core greater than 1.44 the diameter of the sun would end as a supernova. The remnents from the resulting explosion collapse under the force of gravity and keep on collapsin. Mathematically, the process could go until the mass becomes infinitely dense and infinitely small. What happens in reality is that a "black hole" is formed, whose gravity is so strong that light and other energy within its field would be bent so that it would not emanate. The black hole becomes sort of a cosmic vacuum cleaner, sucking up mass and energy.

While the black hole deals with the death of a star, singularity deals with the birth of a universe. Physicists have theorized that at the beginning of time (time is a dimension, but starts at zero and has no negative direction), everything that would comprise the universe was compacted into an infinitely small mass which has infinitely small size. It is as if a black hole had swallowed up all mass and energy (and perhaps this did happen), and suddenly blew up, for reasons unknown. While this can't be proven from direct evidence, the behavior of the universe observed does follow what would be expected from such a model genesis.

Answer 4

Quasars are QUASi stellAR objects. They emit absolutely huge amounts of power, insane amounts, more than whole galaxies, and are very far away.
There is a theory that they are massive black holes eating whole galaxies.
As stuff falls into a black hole it is thought to swirl like water going around as it drains from a sink. The friction, and the compression, heat it so hot it gives off X-rays, as well as lower frequencies.
The first black hole identified was [I think] Cygnus X1, the first X-ray source discovered in the constellation Cygnus.

Bobby is thinking of Pulsars [PULSing stARS], which emit very regular pulses of radio waves.

A black hole is formed when a star of > 1.4 solar masses collapses under its own gravity [after it has burned all it can]. The pressure at the center first squeezes electrons and protons into neutrons [making a neutron star], but then it keeps squeezing.
The star shrinks so small that the escape velocity is higher than the speed of light, so nothing gets out [except by quantum mechanical tunneling per Hawking].

Escape velocity is how fast you would have to throw something upward for it to never fall back down, for it to just keep going away forever. For Earth I think it is 7 miles/second.

Black holes can also form in a nova or a supernova.

Singularity is a term in mathematics for what happens when you divide something by zero - the rules give out.
The graph of 1/(1-X) goes crazy at X=1; that is a singularity.
In this context it is referring to where the gravitational gradient goes nuts at a black hole.

Answer 5

To fully explain these concepts would take an entire book, not the small space we have here.

You need to do some reading - you might check out astronomy.com (or their monthly printed magazine) for well-written (and easy-to-understand) articles each month on these subjects.
You will also find some really good books in the Astronomy section of any large bookstore that will make good reading - glance through a few that seem interesting to see if they "grab" you.

It takes some time and patience to understand some of these concepts, they are not something you find in everyday life. But as you read and learn, you will want to learn even more.

Welcome to the cosmic world of the fascinating.

Answer 6

It is the brightness and most distant objects in the universe.

Answer 7

try a different book.