Gravitational pull definition

December 17, 2015

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Black holes are strange regions where gravity is strong enough to bend light, warp space and distort time. [a href=Credit: NASA/JPL-Caltech

Supermassive black holes may be the result of hundreds or thousands of tiny black holes that merge together. Large gas clouds could also be responsible, collapsing together and rapidly accreting mass. A third option is the collapse of a stellar cluster, a group of stars all falling together.

Intermediate black holes – stuck in the middle

Scientists once thought black holes came in only small and large sizes, but recent research has revealed the possibility for the existence of midsize, or intermediate, black holes (IMBHs). Such bodies could form when stars in a cluster collide in a chain reaction. Several of these forming in the same region could eventually fall together in the center of a galaxy and create a supermassive black hole.

"Astronomers have been looking very hard for these medium-sized black holes, " co-author Tim Roberts, of the University of Durham in the United Kingdom, said in a statement.

"There have been hints that they exist, but IMBH's have been acting like a long-lost relative that isn't interested in being found."

Black hole theory — how they tick

Black holes are incredibly massive, but cover only a small region. Because of the relationship between mass and gravity, this means they have an extremely powerful gravitational force. Virtually nothing can escape from them — under classical physics, even light is trapped by a black hole.

Such a strong pull creates an observational problem when it comes to black holes — scientists can't "see" them the way they can see stars and other objects in space. Instead, scientists must rely on the radiation that is emitted as dust and gas are drawn into the dense creatures. Supermassive black holes, lying in the center of a galaxy, may find themselves shrouded by the dust and gas thick around them, which can block the tell-tale emissions.

black hole particles escapingSometimes as matter is drawn toward a black hole, it ricochets off of the event horizon and is hurled outward, rather than being tugged into the maw. Bright jets of material traveling at near-relativistic speeds are created. Although the black hole itself remains unseen, these powerful jets can be viewed from great distances.

Credit: Karl Tate, contributor

Black holes have three "layers" — the outer and inner event horizon and the singularity.

The event horizon of a black hole is the boundary around the mouth of the black hole where light loses its ability to escape. Once a particle crosses the event horizon, it cannot leave. Gravity is constant across the event horizon.

Under the classical mechanics of physics, nothing can escape from a black hole. However, things shift slightly when quantum mechanics are added to the equation. Under quantum mechanics, for every particle, there is an antiparticle, a particle with the same mass and opposite electric charge. When they meet, particle-antiparticle pairs can annihilate one another.

Freely Falling Objects and Acceleration Due to Gravity
Freely Falling Objects and Acceleration Due to Gravity

What two factors determine the gravitational pull between two object

Mass and the distance between the two masses

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