If you use the Search tool at the top of the page and search on "gravity," many questions will be displayed that you can explore.
*While this is the currently the accepted answer by society, in truth no one knows what gravity truly is. The term "force" is a generalization used to define what they do not understand.
Addition:
There is a theory that gravity is made up of massless, uncharged particles called "Gravitons". This theory isn't widely accepted because gravity doesn't work on a small atomic scale. The theory is called Quantum Gravity.
A black hole is just incredibly dense mass, so dense that it has an incredible gravitational field.
A black hole is made up of nothing.. but gravity. The forces of gravity are so high that not even light can escape.
Black holes are not made of any substance. All of the mass that enters a black hole eventually reaches the "singularity" at the center, where the concept of atoms or density do not exist. It is the concentration of matter to a point that it no longer exists as matter, even as quarks, which are the most massive particles having the highest energy state. The central mass is considered to be concentrated at a point, a region of zero volume. There may also be a huge quantity of captured matter in the process of spiralling down into the hole.
A black hole is a condition in space-time, and can have any amount of mass if that mass is sufficiently compacted. If the mass of the Earth were compressed to a single point it would create a black hole (known as a "mini-black hole"). However, black holes with little matter disappear comparatively rapidly, losing their mass through the release of Hawking radiation.
Typical black holes are formed from dying stars. When the star goes supernova, the remaining mass can form a black hole through gravitational collapse. These black holes have a minimum of about 3 or 4 times the mass of our Sun, and are formed from stars that were originally much larger than that. The black hole will continue to accrete matter, and there is no known upper size limit. But a black hole that does not absorb more mass (as quickly as it radiates energy away) will eventually dissipate.
The theory is that supermassive black holes exist at the center of disk-shaped galaxies such as the Milky Way. These could contain a concentration of millions or even billions of solar masses.
To answer that question, you need to know what a black hole is.
To be brief, a black hole is anything whose mass is so large that it cannot withstand its own gravity, and therefore collapses. At the center of a black hole is what is called a singularity, which is a point of infinite mass and density that creates a gravitational well so deep that nothing, not even light, can escape past its event horizon (point of no return). Only positive energy can escape.
a black hole is made of very dense continously degenerating matter
Answer #2:
It is not completely known how supermassive black holes form but it is thought that they may have formed from originally stellar-mass black holes from massive stars and/or collapsed gas clouds that were able to accrete enough matter and merge with other singularities to form a massive singularity in the order of up to billions of solar masses. These supermassive black holes are able to accrete enough mass from the background radiation that fills the universe to compensate for mass lost from radiating thermal energy (Hawking radiation) and because of this, never evaporate unlike smaller stellar-mass black holes.
A correction to answer #1: Red and brown dwarfs don't have really a chance to ever collapse because they are low-mass stars and in the brown dwarf's case, it may have never even had enough mass to require or even sustain hydrogen-1 fusion. It would also be extremely unlikely that they could accrete anywhere near enough mass to surpass the Chandrasekhar limit, and if one managed to, it would collapse into a neutron star and be supported by neutron degeneracy pressure and would have to continue to accrete massive amounts of mass to surpass the Tolman-Oppenheimer-Volkoff limit to collapse into a singularity. Additionally, it would only be a stellar-mass black hole.
Answer #1:
I know a black hole is created when a star collapses, and I *think* a supermassive black hole is created when a red dwarf collapses. Or a brown dwarf.
No one knows how the FIRST black hole came to be; it happened long before humans roamed the Earth, long before the Earth formed, before the Sun was born. Black holes were probably formed in the titanic explosions of the supernova of massive stars.
Anything. The requirement for a black hole is just sufficient mass in a small enough space.
As far as we know, all black holes are the remnants of "old", large stars dying
and thus they are made up of "star stuff" i.e. mostly hydrogen but with lots of impurities (since the star has converted a good bit of that original hydrogen into all the other elements)
Note that it is quite possible that the entire universe is massive enough (and dense enough) that it is itself a black hole ... in which case the answer is "everything". :)
There is no such thing as "supernatural" black holes. Perhaps you are confusing this with "supermassive" black holes. Those are simply black holes that are quite huge - with 100,000 solar masses or more, some have billions of solar masses - located at the center of galaxies.Regular black holes are made when stars collapse. It is not yet quite clear how the supermassive black holes in the center of galaxies managed to get so big.
Gravity is caused by mass. Wherever there is a mass, there will be gravity.
Despite what you may have heard, the answer is no.
We can't make artificial black holes, but there probably is a black hole being created somewhere in the universe.
Black holes in science fiction movies are giant, black holes that rotate like a circular saws inwards.
The things that we observe as quasars are believed to be caused by huge black holes.
Most black holes are stellar mass black holes with masses comparable to those of large stars as they form from the collapse of massive stars. Scientists know of the existence of supermassive black holes that are millions to billions of times the mass of our sun and can be found in the centers of most galaxies. Scientists still do not know how these black holes become so massive.
X-rays are the best band for studying black holes as the radiations emitted by the black hole is X-rays so we can expect the presence of a black hole anywhere in the Universe.
No. They do not have enough mass to become black holes. Depending on the mass they will either become white dwarfs or neutron stars.
No. It certainly has black holes, but it has other things as well.No. It certainly has black holes, but it has other things as well.No. It certainly has black holes, but it has other things as well.No. It certainly has black holes, but it has other things as well.
Black holes (in the astronomical sense) have never been made in the laboratory.
2010
He did not. He made some theoretical discoveries about how black holes would probably behave; but the concept of black holes was discovered by others before him.
Most likely in the University classroom as an undergraduate student, that's where most people of his generation learned about black holes. But of course what he learned about was ordinary stellar black holes.It was much later when he made his own "what if" hypothesis on microscopic black holes. After solving the equations of general relativity for this case and including the effects of quantum mechanics, he made his theory including Hawking Radiation, evaporation of black holes, and their eventual explosion. This remains theoretical, as his black holes have still not been observed.
stellar black holes were stars (these are large)primordial black holes were pieces of the big bang (these are microscopic)
Black holes are not composed of matter, and do not have a chemical formula.
Black holes do not die but they can evaporate.
Black holes are round because they are formed from dead stars and white holes. As you can guess a star is a sphere and that is why black holes are round.
Black holes
his amazing discoveries in black holes and quantum theory
There are no black holes in our solar system