what is blackhole?why cant blackholes be seen?ar blackholes considered as matter?

Answer 1

A black hole is an object predicted by general relativity,[1] with a gravitational field so powerful that even electromagnetic radiation (such as light) cannot escape its pull.[2]

A black hole is defined to be a region of space-time where escape to the outside universe is impossible. The outer boundary of this region is called the event horizon. Nothing can move from inside the event horizon to the outside, even briefly, due to the extreme gravitational field existing within the region. For the same reason, observers outside the event horizon cannot see any events which may be happening within the event horizon; thus any energy being radiated or events happening within the region are forever unable to be seen or detected from outside. Within the black hole is a singularity, an anomalous place where matter is compressed to the degree that the known laws of physics no longer apply to it.

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).

Answer 2

A black hole is a region of spacetime from which nothing can escape, even light.

To see why this happens, imagine throwing a tennis ball into the air. The harder you throw the tennis ball, the faster it is travelling when it leaves your hand and the higher the ball will go before turning back. If you throw it hard enough it will never return, the gravitational attraction will not be able to pull it back down. The velocity the ball must have to escape is known as the escape velocity and for the earth is about 7 miles a second.

As a body is crushed into a smaller and smaller volume, the gravitational attraction increases, and hence the escape velocity gets bigger. Things have to be thrown harder and harder to escape. Eventually a point is reached when even light, which travels at 186 thousand miles a second, is not travelling fast enough to escape. At this point, nothing can get out as nothing can travel faster than light. This is a black hole.

It is impossible to see a black hole directly because no light can escape from them; they are black. But there are good reasons to think they exist.

When a large star has burnt all its fuel it explodes into a supernova. The stuff that is left collapses down to an extremely dense object known as a neutron star. We know that these objects exist because several have been found using radio telescopes.

If the neutron star is too large, the gravitational forces overwhelm the pressure gradients and collapse cannot be halted. The neutron star continues to shrink until it finally becomes a black hole. This mass limit is only a couple of solar masses, that is about twice the mass of our sun, and so we should expect at least a few neutron stars to have this mass. (Our sun is not particularly large; in fact it is quite small.)

A supernova occurs in our galaxy once every 300 years, and in neighbouring galaxies about 500 neutron stars have been identified. Therefore we are quite confident that there should also be some black holes.

Answer 3

Black holes are matter that is left over from a dead star. If the star was large enough, the inward pressure of all that matter without the outward pressure that was caused by the star radiating energy before it no longer could causes the matter to collapse. The electrons that carry a negative charge and the protons that carry a positive charge fuse together to form neutrons because the force that keeps electrons away from protons is overpowered by the gravity. Now you have a big ball of neutrons. There is still another force that prevents the neutrons from fusing together, but sometimes the leftover matter can be massive enough that even this force is overpowered and gravity compacts it into such a small space that nothing can escape. The reason they can't be seen is because to see them, light would have to bounce off of them or be radiated from them, and any light that gets near it is sucked in too, and any light that would possibly radiate from it is held in tightly by the gravitational force.

All black holes have a surrounding spherical limit known as the "event horizon". Once something crosses that boundary, the gravitational pull becomes so great that it cannot escape under any circumstance. Because of that, nothing within the event horizon can be seen.

Answer 4

A black hole is a cosmic body with gravity so intense that nothing, not even light, can escape. It is suspected to form in the death and collapse of a star that has retained at least three times the Sun's mass. Stars with less mass evolve into white dwarf stars or neutron stars. Details of a black hole's structure are calculated from Albert Einstein's general theory of relativity: a “singularity” of zero volume and infinite density pulls in all matter and energy that comes within an event horizon, defined by the Schwarzschild radius, around it. Black holes cannot be observed directly because they are small and emit no light. However, their enormous gravitational fields affect nearby matter, which is drawn in and emits X rays as it collides at high speed outside the event horizon. Some black holes may have nonstellar origins. Astronomers speculate that supermassive black holes at the centres of quasars and many galaxies are the source of energetic activity that is observed. Stephen W. Hawking theorized the creation of numerous tiny black holes, possibly no more massive than an asteroid, during the big bang. These primordial “mini black holes” lose mass over time and disappear as a result of Hawking radiation. Although black holes remain theoretical, the case for their existence is supported by many observations of phenomena that match their predicted effects.

Answer 5

no longer something. they'd style a large black hollow. To physics the signal of the cost of a lepton does no longer count number. properly, purely about. It concerns for some bypass sections concerning neutrinos and that concerns for the early universe the position more suitable count number than anti-count number become left on the properly of the day. And that concerns to us because we are no longer made from sunshine and neutrinos. yet in a black hollow it does no longer count number. through the time count number disappears below the shape horizon, the weak interplay, it particularly is the purely element that distinguishes count number and anti-count number, has no longer something to assert any more suitable. close to the singularity electromagnetic stress, good stress and weak stress vanish and change into united with gravity to THE stress. And THE stress makes no massive massive difference between count number and anti-count number. So once you're asking a marginally interesting question, the reply is rather boring. :-)

Answer 6

Black holes are said to be relatively smaller area inside which there are very very low pressure, which can absorb everything surrounding it. It is said that a black hole with size of a foot ball can swallow our earth completely.

Every absorbed particles are compressed to some other matter.

Saggitarius A is hypothetically proven nearest black hole region to our Galaxy.

Many scientists believe a black hole can be created inside an particle accelerator.

Answer 7

I am pretty sure that after a supernova (a exploded star) - The core that is left over is the densest matter that there is. It has gravity so strong that light cannot escape - everything that is near it gets pulled to it. We can not see it - or it is "black" to an observer because light surrounding it cannot escape its gravitiation... so it is black...

Answer 8

the explosion of a huge star bigger than a sun is known as supernova. the explosion results to implosion. the implosion results the star to shrink back to asingle point called singularity. the gravity around the point is so high that light cannot escape so it is so black. its density is infinity. this point is called blackhole. this happens when all hydrogen in the star burns to helium.

Answer 9

A blakhole is a big mass falling into itself so dense and so heavy that anything nearby is drawn into it and nothing escapes it, even light emitted from it is absorbed back. So it is not seen.

Answer 10

black hole were stars that died those stars was so so so huge cause not any Star die became a black hole..
and the black hole has a huge gravity that gravt even the light that is why they are called black holes and any planet comes around it the black hole graved it and take it to 3 damnation of the universe at least that is what the scientist thought of..