Why do they call a black hole a hole when it is obviously a sphere?

Question

because if the centre is an infitesimal small point of singularity with an infinite amount of gravity would it not pull in all directions towards it s centre and to say it was a hole would imply that it only pulls in one direction and that you could go around it and look at it from the side

Answer 1

Well, to start with, a black hole can have many "shapes". That is, the event horizon of a black hole (the surface in space beyond which not even light, travelling "straight out" of the black hole, would make it out) can be a kind of smushed shape if the black hole is rotating (that is, that it has angular momentum).

As to the name, it's largely a name. I mean, if not even light can get out from a black hole's event horizon, you're not going to see any light coming from it, are you? So it's black. Moreover, because we have no clue how anything could travel faster than the speed of light, it's hard to see how anything that goes in would come back out. So black holes are kind of like bottomless pits: whatever goes in, doesn't come out. Hence the hole.

Of course, it's worth noting that neither of these points are thought to be exactly correct (facts which came to light long after the name had been coined). Thanks to Prof. Hawking, we believe that black holes actually radiate. The reason we believe this happens isn't because we think things are escaping, but because of quantum mechanical processes that take place near the event horizon of the black hole. This is called Hawking radiation. So, black holes aren't completely black. Moreover, this same process makes the black hole less massive (the process involves anti-matter being thrown into the black hole), but because of the conservation of energy (and/or mass), you can't just destroy energy/mass, so the process also results in particles being emitted from just above the black hole's event horizon (which is the reason mentioned above they're not black). But this means, in some sense, that what goes in also eventually comes out! Not in the same form, but something does. :) So, a black hole, in some sense, is neither wholly black nor a truly perfect hole.

As to the existence of black holes, we do believe we see them. Or at least we see things that if they aren't black holes, we have no clue what they are. In the center of many galaxies, we see huge amounts of energy being released from rather small volumes. The only way we've been able to explain this is to propose that in the center of these galaxies (and indeed perhaps in the center of nearly every galaxy), there are super-massive black holes. In those galaxies where we see a lot of energy released, we believe that lots of gas and dust is falling into such a black hole. But, the gas gets compressed as it moves towards the black hole, hits other gas, and all this results in the release of energy. It's somewhat similar, in some sense, to how a iron rod when it gets hot enough starts to glow red (or white if it gets *really* hot).

As to such a super-massive black hole in the Milky Way's center, we do have some evidence for it. While there isn't any huge energy release going on, there is some (what we think is the Milky Way's black hole is called, I believe, Sagitarius A, I think). But more convincingly, we can see the stars very near the center of the galaxy orbiting around *something* very quickly. By the size of, shape of, and time it takes to finish one of these orbits, we know that there's a *lot* of mass, which we can't see in the visible spectrum, compacted into a *very* small volume. A black hole is a perfect explanation here.

Answer 2

A black hole is a singularity. It is a super-massive sun that goes supernova and then collapses. A sun is a balance of two forces:
Heat pushing to expand and gravity trying to contract.
As the sun loses heat, it collapses in on itself. A large enough star will contain enough mass to continue collapsing to the point of being a singularity.

The shape is not a matter of concern. The point is, a black hole is a point of gravity so strong that even light cannot escape, though there are some forms of radiation that may escape and allow methods to track or identify a black hole.

Answer 3

A black hole is still a theoretical entity.
If a black hole existed it would take the form of a sphere for the same reason that the earth and moon are spheres.
The intense gravity would iron out any lumps or hills on the surface.
There are some good reasons that suggest black holes do not exist!

Answer 4

A black hollow is an stylish theoretical entity,which probable would not exist. it rather is a mathematical equation. If it would desire to exist it would be a 2 to 3 photograph voltaic mass sphere approximately 3 km in diameter whose floor gravity became into such the break out speed from it rather is floor could be better than the cost of light,so it would be invisible. it would act like numerous different celestial physique even nonetheless it would be black.

Answer 5

Several galaxies have black holes as its center. They are for real and exist. They are spherical shape. They are called black holes without the literal meaning..

Answer 6

It is a hole, kind of like a funnel shaped thing in space. It was a sphere once, when a sun imploded upon itself.

Answer 7

Black hole is a dwarf and dead star.which has extra ordinary gravitational pull . it attracts all the things from universe which passes near by.
As in India we say about a very deep and dark well "Andha Kuaan".

Answer 8

It's only a sphere in 4-space. In n-space it's a hole. What you see in 4-space is only the projection of the n-space reality.


Doug

Answer 9

They call it a hole because things fall into it. Black because light does not escape.

Answer 10

They call it a hole, because it is a hole in the fabric of space-time.