Can someone please explain the mass/gravity thing when it comes to black holes?

Question

What I don't get is this... I wouldn't guess that a star that collapses in on itself would have any more mass than what it sterted with (maybe even less)... Why would it have more gravity than it originaly had? I know I must be missing something. Could someone please help me out here? Thanks.

Answer 1

because the same amount or less mass is compressed into a much smaller region of space, it will have more gravity. before some stars become black holes (not all do), they occupy more space. after the star dies, gravity pulls the matter back in on itself, and it occupies less space than the original star did.

think of timespace as a trampoline. when you put 100 lbs of gravel spread out evenly on its surface (this represents the star,) there's not much of a depression. when you pile up the 100lbs of gravel into a spot in the middle (this represents the black hole,) it creates much more of a depression. it is this depression in timespace that creates gravity. the more the depression in timespace, the deeper the gravity well will be.

Answer 2

kevgraz has got it. The mass does not change but the diameter of the objects has gotten really small. Compressing the mass into a smaller volume allows you to get closer to the center of mass without hitting the surface. The strength of gravity goes as 1/R^2, where R is the distance from the center of mass, not distance from the surface. On the surface of the Earth you are still 4,000 miles from the center. Every time you cut the distance to the center in half, gravity goes up 4 fold. If you compressed the Earth to half the size without changing the mass, gravity 4,000 miles from the center would not change but at the new surface 2,000 miles from the center, gravity would be 4 times Earth normal. Gravity does not increase if you dig a hole to get close to the center because all that mass above you cancels out part of the gravity.

Answer 3

The problem is, the amount of mass in the *volume* it occupies...

As you condense a mass, you 'stretch' space. It's easier to think of it like a sheet of rubber - if you have a cone that comes to a sharp point - the rubber can support the dull end of the cone. It depresses the sheet so much, but it's supported. Now, turn it over - and drive the sharp point in. It's the same mass, but it depresses much further. In fact, it'll likely *tear* through the rubber.... and that's essentially what a black hole is - it's more mass in a volume of space than our universe can 'support.' The gravity is so intense, that escape velocity exceeds that of light. As you climb away from the black hole (assuming you could do so), you'd reach a point where orbital velocity would *equal* the speed of light. At this point is where the Event Horizon is. It's the border between where our universe ends, and the black hole's universe begins.

Answer 4

Density creates more gravity than simplistic mass, so if the same object is compressed within it's own matter to a smaller size, the gravity dramatically increases. In the case of a black whole, this occurs in an incredible fashion.

Imagine something 10,000,000 times the mass of the earth compressed into the size of a grain of sand. There is SO MUCH matter into that small tiny dot in space that the gravity rips the very frabric of space itself.

Answer 5

ok, this is an educated guess but. its not a matter of the star gaining more mass. as compared to it lets say having more matter added to it(like it swallows a planet). But more a matter of it's original mass being compacted into say the square root of its original size (that's not an actual accurate account per say of what happens but it puts it in some perspective). for example take a snowball and squeeze it until its no longer a ball of snow but a ball of ice its density changes therefor its mass per square inch. has increased. I would assume the same basic Principal would apply to a degree. also keep in mind the size of the average star that would expect to become a black-hole. It would be perhaps a hundred-thousand times the mass of our planet. now squeeze that mass into say the size six-thousand times our planets size. its density increases exponentialy as would its gravity. Mass bends space-time and creates a gravity field that is capable of accelerating both energy and matter. A black hole contains enough mass in a small enough volume to bend space-time enough to force all matter and energy within a certain distance of the center to move only toward the center. For this reason, even light is trapped by the black hole's gravity. wikapedia is a sure way to get to the root of any question you may have from this attempted explanation.

Answer 6

The mass of a star that metamorphosizes into a black hole does not change- but the size of it does.

It has a gravitational pull that is absolutely enormous, because it becomes extremely dense when it shrinks down to a singularity. Once anything, even light, crosses the event horizon, it is inexorably pulled down into the belly of the black hole.

Gravity does not normally effect light waves, unless the force is in the billions of G's. When the gravity is that tremendous, light bends backwards onto itself.

Answer 7

first of all, the lads who've started the rumor approximately black holes eating up the planet say that it could take 4 years. additionally, even however the gadget would be fired up formally on Wednesday (it is been working for assessments for incredibly it slow already), the energetic collisions are no longer planned till October. So Wednesday looks risk-free. Even greater effective. On a reliable day, the collision may be waiting to unencumber "as much as" 7 TeV (a tera-electron-volt is a huge unit of capability once you're in particle physics -- it is comparatively small once you examine it with "regularly occurring-existence" capability). Cosmic rays do hit the atoms in Earth's environment with energies previous one hundred TeV (a minimum of 14 cases enhanced). So, the black holes created by ability of the LHC would desire to be a minimum of 14 cases much less risky than the black holes that would desire to have been created by ability of cosmic rays for over one billion years. incredibly, IF (a huge if) a black hollow is created by ability of the LHC, we will not additionally be waiting to locate it because of the fact it would final for an particularly little while 0.0000000000000000000001 2nd (there are 21 zeros after the decimal element). In that element, the black hollow does no longer even have time to flow right into a proton and dad out on the different ingredient, it could evaporate earlier. Plus it could probable greater healthful between the quarks that form the proton (it is going to be that small). greater probably, it won't have time to touch something in any respect. the excellent we are able to do is attempt to locate the reasonable postpone between the capability being produced and the recent debris which would be created by ability of that capability (it incredibly is how colliders have labored for some years now). some human beings desire that we are going to be waiting to locate this very short postpone because of the capability being trapped in a black hollow earlier it evaporates. My guess is that we isn't waiting to. In different words, my guess is that we are going to no longer additionally be waiting to understand that a black hollow existed for that short a time, and a few scientists will additionally end that such black holes can not exist. as quickly as we are able to construct a collider that would have a similar capability as cosmic rays (probable in 50 years or so), then we will have a greater effective theory.

Answer 8

Only certian star's do this. Dwarf star's tend to have this happen alot. when some stars die then collaspe this collapsing only happens when a star has low frequnscy and high vallastey some times the frequnscy is so low and the vallastey is so high it inploiuds witch makes it have alot more mass and soon start inploding everything around threre four a black hole.
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Answer 9

The gravity of an object is determined not only by its mass, but also by the distance the observer is away from its center.

When the object collapses, all of its mass becomes concentrated in a single point. This is known as a singularity.

While the strength of the object's gravity doesn't increase, the distance an observer can be away from its center has the potential to be zero.

mass x gravity constant
------------------------------------------ = Force of gravity
(distance from observer)^2

therefore:

mass x gravity constant
------------------------------------------ = INFINITE
0

Answer 10

It has more mass then when it started because it's density is so high.
http://en.wikipedia.org/wiki/Black_hole

that site can probably explain it better then I can.