How does a black hole work?

Question

I want to study astronomy when I get older and I just realized that I have no idea how a black hole works. I'm also interested in finding out about the expansion of the universe. They say that ever since the big bang, the universe has been expanding. Is that true? If so, what is it expanding into? Just curious... O_o ?

I would also like to hear opinions on the "big bang" theory. I'm not sure what that's all about.

Answer 1

Black holes are a area of the universe that is extremely dense. A part of the black hole has infinite density. That's because mass is in a area of zero volume. A black hole can range from 30 kilometers to up to 3 billion kilometers. The mass of a black hole ranges between 3^31 kilograms to 3^39 kilograms. Black holes are thought to be a deep hole in spacetime, where beyond it's event horizon, not even light can escape. However, if you are far away from the event horizon, you'll probably just orbit the black hole. Black holes are thought to be in the center of every galaxy, including the Milky Way.

About the expanding universe, the universe IS expanding. That's why scientists have developed the theory of the Big Bang. Although we know the universe is expanding, we don't know if the if the universe will expand for a infinite time or a finite time. It really depends on how much dark matter there is. The more there is, the higher chance that the universe will collapse. The less there is, the higher chance the universe will end by something else, like the Heat Death, where matter will disappear and no more energy can be created.

Answer 2

Well a black hole is a sun about 100X's bigger than our current sun and when it explodes (also known as a supernova) it's gravity is so strong that it implodes and then the size of that star gets about the size of a period/dot then the gravity from it being great it actually gets sooo heavy it rips through the fabric of space & time -However there are such black holes that are known as super massive black holes that are huge,in fact we have such a black hole located in the middle of our milky way galaxy -The universe is in fact expanding as well, we know this because as time goes by the galaxies ar going further from each other and it will continue (as far as we know) forever..Hope that helped-

Answer 3

A black hole is something that is about the size of an atom, but has an enormous mass (like, more than earth). It's huge mass causes things in the universe to be drawn to it because of gravity. Instead of just revolving around it like a moon around the earth, the gravity is so strong that it literally pulls the object (be it a planet, sun, asteroid, meteor, whatever) into itself, somehow condensing it down to the size of an atom.

Answer 4

i will explain it in a very simple way. A black hole is formed when a star like our sun gets bigger and bigger untill it is a red giant. that will cause everything orbiting it to be consumed and the mass will become so great that it shrinks into a white dwarf because of the heat. more and more thing will continue to be sucked into it and be incinerated. which will increase the mass even more.eventually the mass is so great it implodes literally falling in onto itself getting to a very small size like a pea or grapefruit. it will still keep all its mass but it will have ripped through the "fabric" of space creating a wormhole. these are hole in space that lead to another place in space. it is impossible to tell where they lead but if you were to be suck into one you would be stretched like spahgetti.since the black holes are so dense space clouds (clouds of dust and metors millons of miles long ) form around them and clump together creating a new galaxy like the milky way. i hope this helps.

Answer 5

[edit] Formation
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.

Answer 6

black hole is formed when a star stops giving heat and light .when nuclear reactions are taking place the effect of shrinking under its own mass is balanced by force of nuclear reaction taking place .But when nuclear reaction wents out only the effect of shrinking remains and due to which its volume decreases and thus density increases .and the effect of gravity increases to such extent that it attracts anything that passes by .Its gravity is so high that it doesnot allow even light to escape