Are black holes like vacuum cleaners?

Answer 1

A black hole appears black because not even light can escape the gravity of the hole. So it looks black, as there is no light coming off of it.

More answers:

• A black hole is not black. It only apears so. There is no color, no light escaping it. What you "see" is only the "event horizon." This is the point of no return and to where time is "stopped" at the moment that the star collapsed. And truthfully, you can't even see a black hole. You can find the readings of X-rays and Gamma rays from it, and possibly see the accretion disc.
• The answer to your question depends on your definition of "black" and "color." If color is defined by what your eyes see, then no, black holes do not have color due to the absence of light that enables your eyes to see black. On the other hand, if you meant color in a more abstract sense, black holes are really black, since there is no light bouncing of the black hole to enable your eyes to see it (i.e., if there was light that allows you to see the "blackness" of the hole, it wouldn't be black). Having said this, a black hole in the first example should be defined by the color "null".
• Black holes really are black. However, the area of space NEAR a black hole glows with many types of radiation, because the particles of mass that fall into the black hole are accelerated to the speed of light. So while the black hole is itself black, the area around it would glow brightly in x-ray and gamma ray frequencies.
• Black here meaning they (inside a certain region - the event horizon) give off no light nor do they reflect any; if a black hole is not actively "ingesting" some celestial object it will not be visible. All light we get from around it will be warped (gravitational lens effect) and nothing will be coming from the dead star itself. About the warping (bending light) - imagine space is a stream, and you place a perfectly clear pole in the water - then you take your camera and point at it closely - the change in flow seen by the camera is like the light bending around a black hole.
• If the black hole is near a celestial body (another star, a comet, even a large planet) you will be able to see the effect and if they are close enough you can see a huge jet of material feeding into the black hole: it should get brighter and brighter as it approaches the black hole then very quick disappear. However, one theory is that black holes will continuously give off what is known as Hawking radiation: as virtual particles and antiparticles are spontaneously created (and then immediately recombined), there will be some perfect distance away from the black hole in which one half of the set is swallowed up by the black hole, while its partner lives to fly away, now fully-realized. Dr. Hawking himself believes that this phenomenon occurs at the black hole's event horizon, and that as a result of it, the black hole will continually glow with a detectable stream of energy caused by collisions between energetic particles and antiparticles.

Answer 2

No. The idea of black holes being like vacuum cleaners is grossly inaccurate. A black hole is an object that has completely collapsed under the force of gravity. At large distances the gravity is no different from any other object of the same mass. At close range the gravity is much stronger and things start to get strange. The large mass in such a small area severely distorts space and time. Within a boundary called the event horizon the distortion becomes so great that the only paths forward in time go inward so nothing, not even light, can escape.