Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: syhprum on 01/12/2009 21:48:22
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Let us know what you think
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Let us know what you think
A singularity is inevitable after the event horizon. Unless you can be as speedy as tachyon.
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Nobody knows and it is not ever likely to be able to be tested by experiment. It maybe that we will learn that the question is actually not a meaningful one to ask.
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Let us know what you think
A singularity is inevitable after the event horizon. Unless you can be as speedy as tachyon.
By the way... not to confuse, but what i said is true - also depending on the information loss paradox being solved by Hawking... There are four boundaries in a black hole. If you are lucky enough to be in the inner-boundary, it would look like the universe we imperatively-observe today.
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Mr. Scientist
What are the four boundaries?
Thank you my friend!
Webo
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My bet is neither.
The most likely thing to my mind is another universe that could have similar (but not necessarily exactly the same) properties as ours.
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Mr. Scientist
What are the four boundaries?
Thank you my friend!
Webo
It was in 1935, Albert Einstein and Nathan Rosen predicted that black holes themselves where natural bridges into another possible universe. This bridge from one world into another, came to be known as the 'Einstein-Rosen Bridge,' and most of the developments of this theory came from several physicists - some being Arthur Eddington, John Wheeler and Martin Kruskal.
So let's imagine i decided to jump into a spinning black hole inside a space ship... what would i see? Well, before i entered, i would see nothing spectacular. I would just see a big ball of darkness. I wouldn't even see it rotate at first - neither do i feel anything - i am in what is called a state of 'free-fall'.
Free-fall is when all the atoms and molecules i am made of are all being pulled at the same rate. Even my ship is being pulled at the same pace towards the black hole. A good way to compare this is with astronauts that orbit our earth - they too are in a state of free-fall.
Now i begin to pass the event horizon (remember that is the first boundary, or surface). Now something quite remarkable happens. The space coordinates switches roles with the time coordinate. What does this mean? Well, we move through space freely, back and forth without any problems, and when we consider time, that imaginary dimension, we tend to think we sweep along with it without recourse. Once i pass the event horizon space begins to drag me and my ship, and i begin to move in one direction only - that being forward - however, i begin to move through time backwards and forwards, just as easily as i had moved through the space dimension. In this case, we say that space has become 'timelike', and time has a 'spacelike' character - they are thus interchangeable given the correct conditions.
As i move closer and closer to the black hole, the force of gravity becomes stronger and stronger. Now, suppose my legs are closer to the dreaded center of the black hole, i will begin to feel as if my body was being stretched. A greater force will be pulling at my feet, than that of the force pulling at my head. This is called the 'gravitational tidal effect' - thus called because it is similar to the tidal effect on earth caused by the moon.
Now mind, we have passed the first horizon.. the one which causes a boundary in spacetime. But you might be lucky enough to reach a second horizon where spacetime take their original roles again (and as some have hypothesized before me (well before 1985 :)) our universe could seem like this inner horizon, which in these cases can be thought of as a switching of the metric spatial components with that of the temperal.
Now, if one passes by the singularity, we might be able to move out of the inner horizon and pass through a second inner horizon, and then by finally passing another outer horizon, we will have entered another universe - but i had better be careful. There is a very good chance that this universe is made up mostly of antimatter. If i come into contact with antimatter, me and my ship will explode in a flash of light.
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What is beyond the event horizon of a blackhole?
Nothing. There is no beyond it. At the event horizon of a black hole, the time dilation is infinite for observers in the universe at large. That means the "coordinate speed of light" is zero. So a photon heading towards the black hole simply stops.
People talk about the "proper time" of an infalling observer, but imagine this is being measured using a light clock. That photon has stopped, so that light clock is stopped too. That proper time is being measured with a stopped clock. So it isn't proper at all.
Since we define our second and our metre using the motion of light, when light doesn't move you can't measure anything. So the internal dimensions of the black hole are undefined.
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What is beyond the event horizon of a blackhole?
Nothing. There is no beyond it. At the event horizon of a black hole, the time dilation is infinite for observers in the universe at large. That means the "coordinate speed of light" is zero. So a photon heading towards the black hole simply stops.
This claim is only true in some coordinate systems. In others, this mathematical artefact disappears.
People talk about the "proper time" of an infalling observer, but imagine this is being measured using a light clock. That photon has stopped, so that light clock is stopped too. That proper time is being measured with a stopped clock. So it isn't proper at all.
Actually, you have it exactly backwards. The light clock matches the proper time and the infalling observer sees the light clock operate normally.
Since we define our second and our metre using the motion of light, when light doesn't move you can't measure anything. So the internal dimensions of the black hole are undefined.
We don't do this.
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My view then :)
What we have to play with is the EV. Behind that there is only speculation and hyperbole. Very fun to play with, as they allow for all kind of possibilities, including BH having a SpaceTime of their own. As for the possibility of four boundaries? or time switching place with space?
Ah, It's called SpaceTime because it is. You know -S p a c e T i m e- as a whole concept, undividable. That we still want to divide it is a truism created out of our idea of one last single essence, that 'philosophers stone' that all other things are expected to be built of.
Time as such is a concept valid inside SpaceTime but what will wait inside the event horizon? You can see it two ways. Either you can look at the EV as some sort of 'barrier' separating SpaceTime from another 'place' resembling our own, that is with coherent laws, even if unknown by us. If so you are free to build your own universe, a little like Mr S. does here. Or you can look at it as a place without what we deem as 'laws'.
I'm guessing that the reality of it will be the last one. You could see it as the opposite of law, that is chaos :) the other side of our mirror so to speak. But in reality as we can observe it, consisting of 'nothing'.
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Actually, you have it exactly backwards. The light clock matches the proper time and the infalling observer sees the light clock operate normally.
No, I don't. At the event horizon the infinite time dilation means c=0. What that means in the real world is that light doesn't move. Hence the infalling observer doesn't see the light clock operate normally. He cannot define a coordinate system, because a coordinate system is based on rods and clocks based in turn on the metre and the second which are themselves defined using the motion of light. Light doesn't move means he doesn't see at all. What you think he sees, is in a never-never land of mathematical abstraction beyond the end of time.
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As I understands it.
From an observers standpoint outside the EV a 'in falling object' will take 'forever' to pass the EV. The closer it comes the slower it will seem to move, in the end it will just 'hang' there.
If you instead look at it from the in falling objects view its time will 'be as usual', like when checking heartbeats against his own clock. Instead it might seem as (guessing here) if the EV was 'backing up' as he, no matter his velocity, won't reach pass it in his lifetime. But I still expect him to pass the EV at some measurable time, but then again, others sees it as if he never will.
And that is the crux of the matter, either he does, and then we have black holes created 'daily', or he doesn't and then all black holes came to be at the Big Bang, or how ever else you deem SpaceTime to have come to be.
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Although there is a third possibility, that according to his clock he will pass the EV alive, as his relation toward our SpaceTime allows him to live 'forever' as seen from our observers point of view. And if that is true then it doesn't matter what 'time' we deem it to take. Although it does :) If now our SpaceTime dies its entropic death before that.
But we don't know, we don't work on those timescales, so we can't really test it.
LHC may be able to prove it one way or another with their idea of creating black mini holes..
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There is also a possibility , possibly, of black holes being able to be created without them being able to 'feed' on mass afterwards? But that one feels very strange to me.
They do seem to come in different 'sizes'?
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From a distant observer's perspective, when another object falls into a BH, any clock on that object will slow. The gravity well of the BH will hugely redshift the "ticks" being emitted. Yor-on, you are right that you can, as a distant observer, never see the object cross the EH. However, when viewed from distance, the combined mass of the object and the BH will increase the BH size and do so in a non-symmetric way so as to encompass the object. I assume that this abnormality settles down back to a sphere after some time (observer frame).
However, this one postulate but I believe there are others.
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Farsight you are still wrong. AS I pointed out to you before, you attributing properties associated with a singularity or someone viewing from a distance to those experienced by a body falling through an event horizon. Nothing much happens to an object moving through an event horizon except (from the point of view of the object) that you are cut off from the rest of the universe. It would be quite possible to pass through the horizon of a very large black hole without noticing much other than the distortion of the image of the rest of the universe. Time definitely does NOT slow to a stop there.
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I agree with Soul-surfer here. From the point of view of a person falling into a BH he may not even realise he has crossed the EH (if the BH was large enough that the tidal forces had not killed him). The local space around him would not be noticebly different from normal space. The EH that he would perceive (rather than the dfinition of the EH as seen from a long way of) would recede before him.