black holes... any one?

Question

what is a black hole, where does it come from, whats it made of, where does it lead, and how did they get there, what is their purpose, and why am i obsessed with them

Answer 1

The answers can be found below:
http://cosmology.berkeley.edu/Education/BHfaq.html

Answer 2

They are a spherical volume of concentrated mass.The law of gravity has created them,best we know,some think gravity isn't a law that pulls in but maybe actually pulls out in the universe.Scientist think galaxies have a black hole in the center,so they travel about just like any other cosmic body.I imagine they came about by the imperfection of the new universe to explode in a way as not to create them.All matter is drawn by gravity towards another mass thats why black holes exist.A piece of a black hole the size of a golf ball has the same mass as the entire Earth.Imagine how dense a black hole ought to be to create an orbit of a galaxy?Very enigmatic topic so much to comprehend

Answer 3

Can't answer your last question, but I'll take a stab at the rest of your questions.

A black hole is formed (theoretically) when a neutron star (a star about the size of an Earth city composed of nothing but neutral atomic nuclei) is overwhelmed by its gravitational force that not even the atomic nuclei (neutrons) can hold the star up under the gravitational pressure. Nobody knows how you could actually squish a neutron, but the point is that the neutron star's gravity at that point is so immense that the escape velocity needed to go into orbit around the star exceeds the speed of light. By comparison, the escape velocity from the Earth's gravity is about 7.5 miles per second. The neutron star's escape velocity in this case exceeds 186,000 miles per second. This means that light is trapped. If we can't see any light, we can't really obtain much information about a black hole. A black hole is like a captured military prisoner who will only reveal his name, rank, and serial number. A black hole will only reveal its mass, charge, and spin. That's it.

The center of the black hole is theorized to be an infinitely dense point, called a "singularity." By definition, we can't see the "singularity" -- the singularity is referred to as "cloaked" due to quantum laws. In other words, our current understanding of quantum theory forbids us to see the singularity, even if we could go inside a black hole and look at it. This is no mere play of words, it is backed up by much study and evidence of the nature of quantum indeterminacy. Nobody really understands quantum theory, but it works with stunning accuracy, so scientists use the theory to build amazing things like computers and color TV sets, but no scientist will tell you they understand why quantum theory works.

Understanding a black hole is along the same lines. Scientists jokingly say "a black hole has no hair," meaning it can't be analyzed other than mass, charge, and spin.

So, a black hole is made up of what used to be neutrons. A neutron is composed of two "down" quarks and one "up" quark. If I had to guess I would say the neutrons are broken up into free quarks, but who knows. Another word for "quark" is "string." (See, Superstring Theory).

Where does it lead? Oh, I dunno. Into another dimension. Ooooooohhhh, cooool.

What's their purpose? Good question. It is theorized they powered early galaxies (quasars), and that most large galaxies, like our own Milky Way, have one or more supermassive black holes (a million or more solar masses) at their centers. Once we understand galactic evolution better, we may understand what purpose black holes serve, if any. As for galaxies, they DO serve a purpose -- the life and birth of stars. The purpose of stars, I believe, is to make solar systems with planets. We know the purpose of planets -- to make life.

Really interesting stuff.

Answer 4

its far in space if you go close to it it will suck you in and you will never come out, some say a black hole takes you to another universe

Answer 5

Check this cool site:

http://science.howstuffworks.com/black-h...

for some explanations on what black holes are and how they work. Have fun!!

Answer 6

A black hole is an object predicted by general relativity[1] with a gravitational field so strong that nothing can escape it — not even light.

A black hole is defined to be a region of space-time where escape to the outside universe is impossible. The boundary of this region is a surface called the event horizon. This surface is not a physically tangible one, but merely a figurative concept of an imaginary boundary. Nothing can move from inside the event horizon to the outside, even briefly.

Theoretically, a black hole can be any size. Astrophysicists expect to find black holes with masses ranging between roughly the mass of the Sun ("stellar-mass" black holes) to many millions of times the mass of the Sun (supermassive black holes).

The existence of black holes in the universe is well supported by astronomical observation, particularly from studying X-ray emission from X-ray binaries and active galactic nuclei. It has also been hypothesized that black holes radiate energy due to quantum mechanical effects known as Hawking radiation.

General relativity (as well as most other metric theories of gravity) not only says that black holes can exist, but in fact predicts that they will be formed in nature whenever a sufficient amount of mass gets packed in a given region of space, through a process called gravitational collapse; as the mass inside the given region of space increases, its gravity becomes stronger and (in the language of relativity) increasingly deforms the space around it, ultimately until nothing (not even light) can escape the gravity; at this point an event horizon is formed, and matter and energy must inevitably collapse to a density beyond the limits of known physics. For example, if the Sun was compressed to a radius of roughly three kilometers (about 1/232,000 its present size), the resulting gravitational field would create an event horizon around it, and thus a black hole.

A quantitative analysis of this idea led to the prediction that a stellar remnant above about three to five times the mass of the Sun (the Tolman-Oppenheimer-Volkoff limit) would be unable to support itself as a neutron star via degeneracy pressure, and would inevitably collapse into a black hole. Stellar remnants with this mass are expected to be produced immediately at the end of the lives of stars that are more than 25 to 50 times the mass of the Sun, or by accretion of matter onto an existing neutron star.

Stellar collapse will generate black holes containing at least three solar masses. Black holes smaller than this limit can only be created if their matter is subjected to sufficient pressure from some source other than self-gravitation. The enormous pressures needed for this are thought to have existed in the very early stages of the universe, possibly creating primordial black holes which could have masses smaller than that of the Sun.

Supermassive black holes are believed to exist in the center of most galaxies, including our own Milky Way. This type of black hole contains millions to billions of solar masses, and there are several models of how they might have been formed. The first is via gravitational collapse of a dense cluster of stars. A second is by large amounts of mass accreting onto a "seed" black hole of stellar mass. A third is by repeated fusion of smaller black holes. Effects of such supermassive black holes on spacetime may be observed in regions as the Virgo cluster of galaxies, for example, the location of M87 (see image below) and its neighbors.

Intermediate-mass black holes have a mass between that of stellar and supermassive black holes, typically in the range of thousands of solar masses. Intermediate-mass black holes have been proposed as a possible power source for ultra-luminous X ray sources, and in 2004 detection was claimed of an intermediate-mass black hole orbiting the Sagittarius A* supermassive black hole candidate at the core of the Milky Way galaxy. This detection is disputed.

Certain models of unification of the four fundamental forces allow the formation of micro black holes under laboratory conditions. These postulate that the energy at which gravity is unified with the other forces is comparable to the energy at which the other three are unified, as opposed to being the Planck energy (which is much higher). This would allow production of extremely short-lived black holes in terrestrial particle accelerators. No conclusive evidence of this type of black hole production has been presented, though even a negative result improves constraints on compactification of extra dimensions from string theory or other models of physics.
In theory, no object within the event horizon of a black hole can ever escape, including light. However, black holes can be inductively detected from observation of phenomena near them, such as gravitational lensing, galactic jets, and stars that appear to be in orbit around space where there is no visible matter.

The most conspicuous effects are believed to come from matter accreting onto a black hole, which is predicted to collect into an extremely hot and fast-spinning accretion disk. The internal viscosity of the disk causes it to become extremely hot, and emit large amounts of X-ray and ultraviolet radiation. This process is extremely efficient and can convert about 10% of the rest mass energy of an object into radiation, as opposed to nuclear fusion which can only convert a few percent of the mass to energy. Other observed effects are narrow jets of particles at relativistic speeds heading along the disk's axis.

However, accretion disks, jets, and orbiting objects are found not only around black holes, but also around other objects such as neutron stars and white dwarfs; and the dynamics of bodies near these non-black hole attractors is largely similar to that of bodies around black holes. It is currently a very complex and active field of research involving magnetic fields and plasma physics to disentangle what is going on. Hence, for the most part, observations of accretion disks and orbital motions merely indicate that there is a compact object of a certain mass, and says very little about the nature of that object. The identification of an object as a black hole requires the further assumption that no other object (or bound system of objects) could be so massive and compact. Most astrophysicists accept that this is the case, since according to general relativity, any concentration of matter of sufficient density must necessarily collapse into a black hole.

One important observable difference between black holes and other compact massive objects is that any infalling matter will eventually collide with the latter at relativistic speeds, leading to emission as the kinetic energy of the matter is thermalized. In addition thermonuclear "burning" may occur on the surface as material builds up. These processes produce irregular intense flares of X-rays and other hard radiation. Thus the lack of such flare-ups around a compact concentration of mass is taken as evidence that the object is a black hole, with no surface onto which matter can collect.


[edit] Suspected black holes

Location of the X-ray source Cygnus X-1 which is widely accepted to be a 10 solar mass black hole orbiting a blue giant star
An artist depiction of two black holes merging.There is now a great deal of indirect astronomical observational evidence for black holes in two mass ranges:

stellar mass black holes with masses of a typical star (4–15 times the mass of our Sun), and
supermassive black holes with masses ranging from on the order of 105 to 1010 solar masses.
Additionally, there is some evidence for intermediate-mass black holes (IMBHs), those with masses of a few hundred to a few thousand times that of the Sun. These black holes may be responsible for the emission from ultraluminous X-ray sources (ULXs).

Candidates for stellar-mass black holes were identified mainly by the presence of accretion disks of the right size and speed, without the irregular flare-ups that are expected from disks around other compact objects. Stellar-mass black holes may be involved in gamma ray bursts (GRBs); short duration GRBs are believed to be caused by colliding neutron stars, which form a black hole on merging. Observations of long GRBs in association with supernovae[6][7] suggest that long GRBs are caused by collapsars; a massive star whose core collapses to form a black hole, drawing in the surrounding material. Therefore, a GRB could possibly signal the birth of a new black hole, aiding efforts to search for them.

Candidates for more massive black holes were first provided by the active galactic nuclei and quasars, discovered by radioastronomers in the 1960s. The efficient conversion of mass into energy by friction in the accretion disk of a black hole seems to be the only explanation for the copious amounts of energy generated by such objects. Indeed the introduction of this theory in the 1970s removed a major objection to the belief that quasars were distant galaxies — namely, that no physical mechanism could generate that much energy.

From observations in the 1980s of motions of stars around the galactic centre, it is now believed that such supermassive black holes exist in the centre of most galaxies, including our own Milky Way. Sagittarius A* is now generally agreed to be the location of a supermassive black hole at the centre of the Milky Way galaxy. The orbits of stars within a few AU of Sagittarius A* rule out any object other than a black hole at the centre of the Milky Way assuming the current standard laws of physics are correct.


The jet emitted by the galaxy M87 in this image is thought to be caused by a supermassive black hole at the galaxy's centreThe current picture is that all galaxies may have a supermassive black hole in their centre, and that this black hole accretes gas and dust in the middle of the galaxies generating huge amounts of radiation — until all the nearby mass has been swallowed and the process shuts off. This picture may also explain why there are no nearby quasars.

Although the details are still not clear, it seems that the growth of the black hole is intimately related to the growth of the spheroidal component — an elliptical galaxy, or the bulge of a spiral galaxy — in which it lives.

In 2002, the Hubble Telescope identified evidence indicating that intermediate size black holes exist in globular clusters named M15 and G1. The evidence for the black holes stemmed from the orbital velocity of the stars in the globular clusters; however, a group of neutron stars could cause similar observations.


[edit] Recent discoveries
In 2004, astronomers found 31 candidate supermassive black holes from searching obscured quasars. The lead scientist said that there are from two to five times as many supermassive black holes as previously predicted.[8]

In June 2004 astronomers found a super-massive black hole, Q0906+6930, at the centre of a distant galaxy about 12.7 billion light years away. This observation indicated rapid creation of super-massive black holes in the early universe.[9]

In November 2004 a team of astronomers reported the discovery of the first intermediate-mass black hole in our Galaxy, orbiting three light-years from Sagittarius A*. This medium black hole of 1,300 solar masses is within a cluster of seven stars, possibly the remnant of a massive star cluster that has been stripped down by the Galactic Centre.[10][11] This observation may add support to the idea that supermassive black holes grow by absorbing nearby smaller black holes and stars.

In February 2005, a blue giant star SDSS J090745.0+24507 was found to be leaving the Milky Way at twice the escape velocity (0.0022 of the speed of light), having been catapulted out of the galactic core which its path can be traced back to. The high velocity of this star supports the hypothesis of a super-massive black hole in the centre of the galaxy.

The formation of micro black holes on Earth in particle accelerators has been tentatively reported,[12] but not yet confirmed. So far there are no observed candidates for primordial black holes.

try for wikipedia and you'll be happy