Ok, going into a bit more detail now
quote:
Originally posted by Time
One thing to dispute here: black holes are NOT objects.
In the loosest possible terms a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull.
(...)
At the singularity our laws of physics no longer apply, the singularity cannot be considered an object at all.
Since the singularity has a mass it can be considered an object; a quantum mechanical object.
quote:
Originally posted by Time
They showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole.
Yes and no.
Certainly not all stars collaps in black holes at all. It is very rarly that it does.
You can devide stars in roughly 2 categories:
1) Stars with masses equal or smaller than +-10 times the mass of the Sun.
2) Stars with masses greater than +-10 times the mass of the Sun.
When a star with a mass equal or smaller than +-10 times the mass of the Sun cools down, and thus is ending its "life cycle" it gets bigger and bigger up to a
red giant.
When growing it also looses layer after layer of material. When the last layer of material is emitted only the core remains. This emitted (last) layer in space is called a
Nebula.
After that the core implodes into itself and is crushed down to a
white dwarf (+-size of the earth).
When the density of the white dwarf is large enough, this core will on his turn implode and will cause such a shockwave that all material surrounding it and including the core is destroyed, this is called a
nova or
super nova type 1. Nothing will remain.
When the density of the white dwarf isn't large enough, the white dwarf will turn into a stable white dwarf and nothing will happen anymore.
When a star with a mass bigger than +-10 times the mass of the Sun cools down, and thus is ending its "life cycle" it gets bigger and bigger up to a
red or
blue supergiant.
Again this supergiant will eventually cause a super nova. But this time a
super nova type 2. The core of the star will not be destroyed, instead it will be crushed down to a
neutron star (+-10km).
When the neutron star spins fast enough, it will become
a pulsar. Again nothing further will happen, although the gravity is extremely large, the rotation prevents it from further imploding.
But when it doesn't rotate fast enough and has a big enough mass, the gravity wins and only then will it turn into
a black hole as there is no or not strong enough anti-gravity force to prevent it.
quote:
Originally posted by Time
In particular, a black hole has something called an 'event horizon.' This is a spherical surface that marks the boundary of the black hole. You can pass in through the horizon, but you can't get back out. In fact, once you've crossed the horizon, you're doomed to move inexorably closer and closer to the 'singularity' at the center of the black hole.
Yes and no.
A black hole has an
outer event horizon and an
inner event horizon. The outer event horizon is the space where you will begin to feel the gravitational pull of the black hole. The inner event horizon is the region you can not escape anymore as the velocity needed to escape that must be greater than the speed of light.
It is this inner event horizon which is called the
Schwarzschild region.
One black hole isn't the same as the other black hole and they can have different masses. The mass can vary from a few solar masses up to the combined mass of millions of galaxies put together.
And because of the mass difference, also the sizes can vary from extremely small as with
mini blackholes to massivly large as with
super black holes.
Black holes can be divided into two main types, or rather their type of singularities:
1) A
point singularity. This type of black hole is what most people think of as a black hole. The point singularity is formed from stationary, non-rotating matter; The black hole doesn't rotate. This is the blackhole associated with Schwarzschild.
2) A
ring singularity. The rotating neutron star isn't crushed into a single point singularity but into a ring because of the rotation. Thus this type of black hole is formed from rotating matter. Space and time surrounding this singularity will be dragged around like a vortex.
And this last type is the interesting one, and the one which is predicted and prooven by Einstein's general relativity theory.
The general relativitly theory says and proofs that you could go into this ring singularity and when you will return you will return before the time you started going into the black hole.
Note that Einstein didn't liked this and was greatly disturb by this as this allowed for possible time travel!
Thus Einstein, together with Rosen, also calculated/prooved that this region within this ring singularity, can be interpreted as some kind of bridge to another spacetime and thus somehow connect different parts of spacetime. Subsequently, these are called
Einsten-Rosen bridges or we know these better as
wormholes.
Up until now, this theory is still not proven 100% wrong. Although the theory of Schwarzschild is one way to proof it wrong. Or rather only to proof that you can't actually travel thru the wormhole to the other universe, you would be stuck in the middle, but you could see the other universe though (The Schwarzschild Bubble and stuff). On the other hand, that same theory of Schwarzschild also allows for the use of negative mass matter which actually could keep the wormhole open to pass thru and thus create a stable Schwarzschild wormhole.
While this negative mass matter is strange and doesn't fit in our current physics (for 100%), we also know there are very exotic things going on when dealing with black holes and we know that there must be something to compensate matter as we know it (black matter, black energy, etc...) in other words: who knows... at least it isn't totally impossible.
quote:
Originally posted by cardshark
Though I read about the theory in a sci-fi novel (Orson Scott Card's Children of the Mind)
That theory is exactly Einstein's General Relativity Theory (well, that is: part of)
quote:
Originally posted by groessl35
But anyways... I don't think it really bends... and sucked into the hole... if the force of gravity in a black hole is too great for a beam of light to escape... would it stand still?
The light emitted from the black hole can't escape gravity and thus it is bend back to the black hole (think of a magnetic field, or solar flames which bend back to the sun), hence we can't see it.
Only when a person is sucked into a black hole and passes the inner event horizon, the observer who is watching will see the sucked in person as if he/she is standing still (forever).
quote:
Originally posted by .Roy
Also i think its possible to see in the past.
If you look at a certain position and go faster then the speed of light, you will see things that happened before ( but in reverse).
no, you wont. You would go so fast that the light emitting from those events will never reach you, aka you would see blackness.
quote:
Originally posted by John Anderton
quote:
Originally posted by Madman
It is impossible to go beond the speed of light because it would require an infinate amount of energy (or somthing like that).
Well ..... its basicallay proved by einsteins rest mass to velovcity mass equation
m = (m0) / (1-v^2/c^2)^1/2
Where m is you mass at velocity v
m0 is your mass at rest (that zero is a subscript 
)
c is the velocity of light
Thus as you velocity approaches the speed of light ... your mass becomes higher. You cant exceed the velocity of light cause well .... root of negative numbers are imaginary
yes, they are imaginary but that doesn't mean it can't exist or be used to develop further theories (heck the imaginary number system and imaginary algebra is teached in every school). And this is actually were the theory of Schwarzschild comes into play; together with white holes, his "bubbles" and wormholes.
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