The thing about black holes is...
Discussion
Frimley111R said:
...they are not holes. So why to do they call them 'holes'? They are just areas of super compact matter with super gravity. I don't understand why people think its a hole? After all, where's the back of it?
Some think the back of it is a white hole in another universe spewing out matter which would be a lovely circle of logic but I suspect isn't true.Is it such a bad description for an area of space that even light cannot escape? For a colloquial term, "hole" seems OK. Yes, you might struggle to visualise a 3D "hole" based around a singularity rather than a "hole" at the end of a tunnel, but I doubt anyone interested in the subject takes long to realise the limitations of the description.
Of course Hawking Radiation and similar would suggest the "black holes" are not quite so inescapable
Frimley111R said:
Yes, I think it is very poor term. People think it really is a hole to somewhere unknown but its not a hole at all, more a 'black area/point which is only black due its ability to stop light escaping. Essentially its just a supper compressed lump of matter with massive gravity. .
I think your meal-related description of the phenomenon lacks a certain catchiness that black hole enjoys. Any simple phrase could be torn apart by bringing in various various properties. The option is to go for singularity, but it is not descriptive but more explanatory.With the description of gravity as a stretched bit of rubber which is distorted by mass, the term hole describes the distortion created by a black hole in that analogy.
Yep not really a hole at all.
Sometimes a black hole may not even be super-condensed matter. For example a super-massive black hole may only have the density of water.
The size of our sun would have to become 3km radius before that became a black hole, where 3km is called the Swartschild radius.
The Earth would have to become a few cm in radius before it would become a black hole.
The blackness of it is more due to the fact that time is curved so much that any radial orbits result in a 'fall' to the centre rather than being able to curve away to an observer that is outside the event horizon.
The event horizon is named such that time appears to stop and no events occur beyond this boundary.
A falling spinning object heading towards the event horizon would appear to increase in speed but at the same time slow in its spin. And when it reached the event horizon it would appear to 'freeze'.
Its a strange realm of physics which I am only repeating videos I've seen, I don't confess to know what is going on in fine details. But it is fascinating.
Sometimes a black hole may not even be super-condensed matter. For example a super-massive black hole may only have the density of water.
The size of our sun would have to become 3km radius before that became a black hole, where 3km is called the Swartschild radius.
The Earth would have to become a few cm in radius before it would become a black hole.
The blackness of it is more due to the fact that time is curved so much that any radial orbits result in a 'fall' to the centre rather than being able to curve away to an observer that is outside the event horizon.
The event horizon is named such that time appears to stop and no events occur beyond this boundary.
A falling spinning object heading towards the event horizon would appear to increase in speed but at the same time slow in its spin. And when it reached the event horizon it would appear to 'freeze'.
Its a strange realm of physics which I am only repeating videos I've seen, I don't confess to know what is going on in fine details. But it is fascinating.
Monty Python said:
Light is not a particle - it is an energy wave.
Also that the famous equation of m = E/C^2 states that everything is basically energy.With 'mass' being a resultant property of the effects of energy with various fields.
A number of years ago when I started gathering more knowledge on physics I found it surprising that every element on the periodic table is 'lighter' than the constituent 'particles' that make them.
For example a hydrogen atom has less mass than the combined mass of a Proton and an Electron.
And this is a result of Einstein's equations and the fact that mass is a resultant property of energy and its interactions.
So I think when looking at the 'very small' you have to think in terms of energy and waves, and not 'particles'.
Edited by AA999 on Tuesday 29th September 12:35
Monty Python said:
Simpo Two said:
So, when light is attracted to the 'hole' and splats onto the surface, what is the residue? - a layer of stationary photons?
Light is not a particle - it is an energy wave.
https://en.wikipedia.org/wiki/Wave%E2%80%93particl...
Simpo Two said:
So, when light is attracted to the 'hole' and splats onto the surface, what is the residue? - a layer of stationary photons?
There is no surface for it to splat on to. The light never stops, the "freezing" is what an outside observe sees as time dilation becomes so great that it appears to take an infinite amount of time for the light to fall into the singularity. From the reference frame of the light it just falls into the singularity, it can't even tell when it reaches the event horizon, since that is only visible to external observers.Flibble said:
There is no surface for it to splat on to. The light never stops, the "freezing" is what an outside observe sees as time dilation becomes so great that it appears to take an infinite amount of time for the light to fall into the singularity. From the reference frame of the light it just falls into the singularity, it can't even tell when it reaches the event horizon, since that is only visible to external observers.
If one travels at the speed of light then time ceases to exist. The event horizon is the 'barrier' where anything falling into the black hole/dark star/singularity reaches the speed of light. bh/ds/s will, according to the latest theories, collapse at the end of the universe. When the universe ends, so will time. So if you want to live forever, go sit on an event horizon.
I've not given this a great deal of thought, and probably less than it deserves, so there might be a small hole or two in the reasoning.
AA999 said:
Yep not really a hole at all.
Sometimes a black hole may not even be super-condensed matter. For example a super-massive black hole may only have the density of water.
The size of our sun would have to become 3km radius before that became a black hole, where 3km is called the Swartschild radius.
The Earth would have to become a few cm in radius before it would become a black hole.
The blackness of it is more due to the fact that time is curved so much that any radial orbits result in a 'fall' to the centre rather than being able to curve away to an observer that is outside the event horizon.
The event horizon is named such that time appears to stop and no events occur beyond this boundary.
A falling spinning object heading towards the event horizon would appear to increase in speed but at the same time slow in its spin. And when it reached the event horizon it would appear to 'freeze'.
Its a strange realm of physics which I am only repeating videos I've seen, I don't confess to know what is going on in fine details. But it is fascinating.
Interestingly enough, the universe's 'black hole' radius is also its observable radius, various caveats notwithstanding. We may already be living in a black hole.Sometimes a black hole may not even be super-condensed matter. For example a super-massive black hole may only have the density of water.
The size of our sun would have to become 3km radius before that became a black hole, where 3km is called the Swartschild radius.
The Earth would have to become a few cm in radius before it would become a black hole.
The blackness of it is more due to the fact that time is curved so much that any radial orbits result in a 'fall' to the centre rather than being able to curve away to an observer that is outside the event horizon.
The event horizon is named such that time appears to stop and no events occur beyond this boundary.
A falling spinning object heading towards the event horizon would appear to increase in speed but at the same time slow in its spin. And when it reached the event horizon it would appear to 'freeze'.
Its a strange realm of physics which I am only repeating videos I've seen, I don't confess to know what is going on in fine details. But it is fascinating.
Flibble said:
There is no surface for it to splat on to. The light never stops, the "freezing" is what an outside observe sees as time dilation becomes so great that it appears to take an infinite amount of time for the light to fall into the singularity. From the reference frame of the light it just falls into the singularity, it can't even tell when it reaches the event horizon, since that is only visible to external observers.
If there is no surface then where did all the matter that the black hole hoovered up go to? I appreciate the thing about stopping at the event horizon, where speed matches escape velocity, but where do the photons actually go?Simpo Two said:
If there is no surface then where did all the matter that the black hole hoovered up go to? I appreciate the thing about stopping at the event horizon, where speed matches escape velocity, but where do the photons actually go?
Nobody actually knows, current theories break down and don't describe what happens.
Derek Smith said:
If one travels at the speed of light then time ceases to exist. The event horizon is the 'barrier' where anything falling into the black hole/dark star/singularity reaches the speed of light. bh/ds/s will, according to the latest theories, collapse at the end of the universe. When the universe ends, so will time.
So if you want to live forever, go sit on an event horizon.
I've not given this a great deal of thought, and probably less than it deserves, so there might be a small hole or two in the reasoning.
From the perspective of the person falling into the black hole time passes normally though. Time dilation is relative to an external observer, not absolute.So if you want to live forever, go sit on an event horizon.
I've not given this a great deal of thought, and probably less than it deserves, so there might be a small hole or two in the reasoning.
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