Thank you for taking the time to explain it in such depth.
I percieve space time as more geometry than anything else. What I am asking I will put another way... short of a drawing ..with this crude description. Say we have a sheet of "graph" paper to represent uncurved space time. In the centre of our page we place a point of mass.. I guess what I ask do the squares become "smaller" (although curved) the closer to the point of mass.
alex
Very interesting tread. I think that if half of Earth disappeared there would be huge explosion as the mass is converted to the energy. Even if there were possible way to make half of the Earth to disappear without converting matter to energy, there would be still explosion, as angular movement of large mass would be instantly destroyed. The other half of the Earth would be blown to dust and scattered over Solar system.
Yes - the squares near the mass would not only appear to get smaller - they would be smaller! The speed of light may be a constant but time certainly isn't and distance = speed * time, so distance is relative too!
Karls
Possibly, if every second atom simply tunnelled through into another reality (or back to the quantum foam) Newton would turn in his grave. By his understanding energy and momentum would have hugely been violated (and possibly no bang occurs) - as there is no conversion, matter simply fades away into another reality. Einstein meanwhile would shout Eureka and modify relativity to say M-Theory is right, there are multiple realities and there must be away to send matter or energy from one to another. So energy and mass and momentum would be coversed (within a transformation function from one reality to another) across membranes / dimensions.
I can agree that the orbit will be ever so lightly larger. My previous change in center of mass was wrong. It wouldn't be 6380km, it would be less than half that.
Paul,
Haven't you made an additional assumption there about which side of the earth has disappearred? What if it was the "outside" (relative the earth) half? Or just for the sake of playing... the "inside" half (the core)...
Al.
Last edited by sheeny; 09-01-2007 at 05:28 PM.
Reason: typo
If on a cosmic scale matter can be created and destoyed without apparently conserving energy or momentum, in finite spots for a finite time, then there is a different framework for studying cosmic expansion other than dark energy or dark matter (or perhaps offering a candidate for them).
So the equivalence of matter and energy (E=mc^2) is bunk????
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Originally Posted by g__day
Hawking has showed its possible for matter or energy to jump from the cosmic foam (alah the world of the really tiny quantum mechanics that our universe appears to float in) and not necessarily spell doom and gloom. Hawkings initial postulate was a pair of virtual particles (pro and anti to conserve mass and energy) tunnel into our reality then immediately zap each other and annihilate... except if they appear near the event horizon of a black hole, so one escapes and one is sucked in. In this situation you've just added mass and energy to the Universe.
I follow the argument but don't agree with the conclusion that matter and/or energy is added to the universe. Is not the black whole part of the universe? While the cosmic foam concept allows us to explain the average statistical behaviour observed at macros scales and reconcile it with quantum theory, each matter/antimatter pair is not serial numbered to only cancel with the partner it was created with.
If an antiparticle is annihalated inside a black hole the gravitational effect outside the black hole does not change (due to mass/energy equivalence).
No, e=mc^2 (in simplified form ignoring momentum for particles with no rest mass), seems pretty solid, but I was saying in a quantum mechanics framework matter or energy can do very, very wierd things - we're do you think that the Universe came from under the Big Bang if it wasn't a quantum fluctation of extraordinary magnitude?
And if a pair of opposite virtual particles get created and one is swallowed by the black hole so the other escapes as a real particles then the universe now has a higher energy density +1 to normal spaceimte in the universe and +1 to blackhole. For the blackhole's gravitational field increases even if anti matter is swallowed (unless I'm just entirely sleep deprived)!
Is a blackhole part of our Universe? Well at least partly it must be. By this I mean it exists in a reality beyond relativity within its event horizon (say for instance the inside is at the energy densities that it is a realm entirely ruled by quantum gravity and the four forces have re-combined back into one). It is unclear then how this inside the event horizon interacts with normal spacetime ruled by relativity, or any other realities beyond spacetime within our universe that it may be connects with.
No, e=mc^2 (in simplified form ignoring momentum for particles with no rest mass), seems pretty solid, but I was saying in a quantum mechanics framework matter or energy can do very, very wierd things - we're do you think that the Universe came from under the Big Bang if it wasn't a quantum fluctation of extraordinary magnitude?
Who knows? A "quantum fluctuation of extraordinary magnitude" may be one possibility, but it's a particularly unpleasant one to consider IMHO. If our universe was created this way, then there is an anti-universe somewhere just waiting to annihalate ours, and it could do so at any time without our ability to detect or predict it. It is in the realm of philosophy not science.
Quote:
Originally Posted by g__day
And if a pair of opposite virtual particles get created and one is swallowed by the black hole so the other escapes as a real particles then the universe now has a higher energy density +1 to normal spaceimte in the universe and +1 to blackhole. For the blackhole's gravitational field increases even if anti matter is swallowed (unless I'm just entirely sleep deprived)!
No, sorry, I don't agree. For the the quantum foam to produce the matter/antimatter pair, the energy had to exist in the universe anyway. For every such pair produced in this way, is it not just as likely that a pair was absorbed by the cosmic foam in the same way? I'm not aware that quantum fluctuations are not an irreversible process. Statistically, quantum fluctuations cancel out.
So I suggest, if the matter/antimatter pair were separated as you describe, the anti particle would annihalate a corresponding matter particle to produce energy, but the total amount of mass/energy in the universe (including the black hole) remains constant.
Quote:
Originally Posted by g__day
Is a blackhole part of our Universe? Well at least partly it must be. By this I mean it exists in a reality beyond relativity within its event horizon (say for instance the inside is at the energy densities that it is a realm entirely ruled by quantum gravity and the four forces have re-combined back into one). It is unclear then how this inside the event horizon interacts with normal spacetime ruled by relativity, or any other realities beyond spacetime within our universe that it may be connects with.
My interpretation is that a black hole is part of our universe, albeit a part we cannot observe the inside of from here.
I know Hawkling has produced mathematical models of what goes on inside black holes but these are even bordering on philosophy. It is all done with extrapolation of the laws of nature as we observe them. As I imagine you are well aware, extrapolation is much less precise (and sometimes very dangerous) than interpolation. Until we work out a way to observe through the event horizon, any theories about what is on the inside of a black hole are far from concrete, because the conditions there differ so immensely from the conditions in which we have developed the laws of nature. Philosophically, all sorts of things could be possible, but scientifically we can say it's a black hole and speculate about what's inside. I have no idea if there's any other sort of "reality" inside a black hole... maybe it's more of the same (simply unable to be observed due to the extreme curvature of space/time at the event horizon), maybe it's bizarrely different. The question is a philosophical one based on today's science.
Hope you don't mind if I chime in and say a few words. Hopefully I'm understanding where some of the debate is coming from.
With regards to QM and virtual particles, conservation of energy is maintained due to the uncertainty principle. While most know this as the relationship between position and momentum, there is also the relationship between energy and time. Two virtual particles can be created so long as the time they exist does not exceed a certain limit. The greater the energy of the particles the shorter the time they can be in existance before they annihilate and give their energy back to the vacuum.
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G__day...
And if a pair of opposite virtual particles get created and one is swallowed by the black hole so the other escapes as a real particles then the universe now has a higher energy density +1 to normal spaceimte in the universe and +1 to blackhole.
When two particles are "created" at the absolute horizon of a BH, and one enters the horizon, the other then becomes a real particle with positive mass and energy (+1 so to speak). The particle that enters the horizon therefore has negative mass (and therefore negative energy), so takes mass away from the BH (-1). The energy density balance in the universe does not change. This is the principle behind Hawking radiation and related black hole "evaporation".
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Sheeny...
For the the quantum foam to produce the matter/antimatter pair, the energy had to exist in the universe anyway.
Correct. It's what is known as vacuum energy. It's a "fluctuation" in this energy that causes the virtual particle pair creation.
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Alex...
I percieve space time as more geometry than anything else. What I am asking I will put another way... short of a drawing ..with this crude description. Say we have a sheet of "graph" paper to represent uncurved space time. In the centre of our page we place a point of mass.. I guess what I ask do the squares become "smaller" (although curved) the closer to the point of mass.
Hi Alex, the squares become longer in the radial direction, but narrower in the "width" direction as they get closer to the mass. The ball on the sheet analogy can be confusing as it's a 3D representation of a 2D plane. Imagine the sheet as being totally flat, and on this flat sheet are the paths that an object can take (distance), but the effect on the object is as though it's on the curved aspect of the sheet (time and acceleration).
I would say if half the earth disappeared then some scientist at some facility would have a hell of a lot of explaining to do as to 'what went wrong?!'
So it appears that I have a fair view of the grid as it were. AND certainly the ball should be under the sheet to even represent that situation.
AL said...
I know Hawking has produced mathematical models of what goes on inside black holes but these are even bordering on philosophy...
I salute your braveness to say such but the truth stands irrespective of the greatness of the man who that may undermine.
His position is very much he can speculate (albeit with presumably sound math models) however in truth he is more of a philosopher than a scientist when in this area for what really goes on at present is beyond observation so ideas will remain simply ideas..my little understanding of scientific methods tells me that it is not a theory until observation support the "idea" and I don’t know that very much of his input does that... mind you his view is not to be dismissed but I think many, because of his intellectual might, are afeared to say what you have said. Congratulations.
Anyways I have noticed so many drawings, artist impressions of light being represented being gravitationally lensed.. it seems to me that who ever is behind many (al I have seen or noticed) have the ball on the blanket concept as the only way they can work with the concept..because "space" is curved around the ball , or in the drawings the object responsible for the gravitational lensing.
I mean the light comes along directly toward the gravitational lensing object then moves out into space and detours around it..so as to produce the effect in the blanket and ball world..I say that view is wrong.. as would anyone when you look carefully at such artist impressions.
alex
Please don't think I'm trying to undermine Hawking!!! He has an exceptional mind! But when you push the boundaries as he does, sometimes the boundary between science and philosphy gets crossed... it's just something we have to recognise and live with until we can move the boundary out around it - by either proving or disproving the idea. Basic scientific method.
No I did not think that ...and I say similar which is possibly interpreted as impertinent but you have called it right. He is a great mind but that does not entitle him to very much more in the speculation department than the rest of us..indeed it entitles him to less in my view. But he is a mighty mind no one can ever take that away from him.. still you are more aware than me, I expect, that you not only have to be clever you have to have observation and experiment.. without which it really is not science I recon.
alex
To refresh ...I said.. Anyways I have noticed so many drawings, artist impressions of light being represented being gravitationally lensed.. it seems to me that who ever is behind many (al I have seen or noticed) have the ball on the blanket concept as the only way they can work with the concept..because "space" is curved around the ball , or in the drawings the object responsible for the gravitational lensing.
I mean the light comes along directly toward the gravitational lensing object then moves out into space and detours around it..so as to produce the effect in the blanket and ball world..I say that view is wrong.. as would anyone when you look carefully at such artist impressions.
What I am driving at if you lay over a grid and the grid lines get "smaller" nearer the "mass" the space time grid suggests to me that light would follow the grid lines, in which case they move towards the mass and when passed the mass move out again. I know the drawing is probably simplified to get the idea across but at that level I see it inconsistent with how space is bent by mass. The illustration and indeed the ball on the blanket approach would see a bend in space that went on forever like placing a bend in a piece of paper.
alex
Here is my view of the way it must work. I am not making a statement as much as questioning what I understand about my space time understanding. Please ignore the grey that is something that crept in trying to merge ovals in word star
alex
I don't take Hawking as gospel, he is merely trying to construct a theoretical / mathematical model for the pyhsics of extreme environments that definitely go beyond relativistic environments. He is stating possible rules for his construct - which we are a long way from scientifically proving yet!
PPS
I must re-read the black hole envapouration scenario - as I didn't get that the "swallowed" virtual particle has negative mass = negative energy = negative entrophy. That gives me a fair headache.
I understand his importance and respect him for his struggle with life, he needs recognition for that if nothing else , but I find some of the black hole radiation thing a bit hard to swallow ..but I dont speak math or physics so what would I know . I find the concept of black holes at the centre of our galaxy somewhat irrelevant as it seems their mass is not sufficient to really be responsible for holding the galaxy together. Their exsistence to me is a little like dark matter ..comes from theory and the observations sortta back up the theory.. but we still cant see one .
Where ever the balck holes are I can not imagine they are at the centre..if two they will form a binary orbit and if more ???..well it matters not they will be destined to orbit the centre not be the centre of the galaxy. Even if one its mass relative to the rest of the galaxy means it will orbit the centre as oppossed to being in the centre. I often wonder therefore if there is a real hole scribed out by the orbits of the inner most black holes.. somewhere the gravity rain can shuffle from one side of the system to the other
Hopelessly irrelevant but that has never stopped me before .
alex
Why an actual hole??? I just cant see an individual black hole making the jets that come out of the galactic "centre" whereas a binary or more system would make a very efficent vortex to propel matter as we observe...using the hole I suggest of course.
alex
Just a note about my major annoyance with black hole discussions:
Accepting there are singularities within the event horizon as a foregone conclusion derived under a non applicable physics model annoys me immensely.
Under relativity nothing stops matter, energy and spacetime from being crushed into a singularity within the event horizon, but its pretty clear relativity doesn't apply within this framework - so why apply its dictates at all?
Model what can happen under quantum mechanics, quantum gravity, loop quantum gravity, SuSy etc
Treat three (?) dimensional space, one dimensional time (?), the equivalance that are matter and energy, which affect properties of both the shape of spacetime and the rate that time passes at a given locale within said spacetime as complex interrelated variable and come up with a scenario that works.
As it stands this singularity as a foregone conclusion is really sloppy science from my perspective. I'd rather it be called X and unknown and try and model it out.
Even the work on massive grav-stars showed if during collapse your sun had massive spin (angular momentum) then a singularity could be avoided.
Personally I think you're going to end up with some pretty wierd, interdependent framework as all the variables interact with one another so they are all kinda self referential. Think about it mass is meaningless without time and space to exist within. Same goes for energy. But energy and mass shape both space and time so they must be able to both move within it, and shape or change it as they move. Mass and energy must interact with both each other and time and space. We still can't model what happens with these interactions when one or more of these properties gets either really big, really small, really heavy, really energetic. At a quantum level all our sciences break down and we need a way of fixing this before we talk about what happens in this domain.
So lets be crystal clear - the four forces affecting matter and energy (gravity, electomagnetism, strong nuclear, weak nuclear) - don't interact clearly in any sort of describable, sensible fashion once you get down to distances that are the size of an atom or smaller! All our powerful, modern physics breaksdown at this level and you really do have to transition to the very wierd and incompletely understood world of quantum mechanics (things appearing, dissappearing, tunnelling, being in more then one place at one time, not always absolutely conserving mass nor energy, not every having a specific location, inbuilt uncertainity dominating their actions, never being at absolute rest etc ... acting probablistically) to model reality. Until we better understand the interactions between all the dynamic changes to the geometry of spacetime and things within it at both the nano and macro scales - our physics and understanding of reality is very incomplete.
Well I am doing my best to come up with TOE but I have had to put it to one side to get the grass mowed. Hawking said at one point he gets about 3 TOE's in the mail each day so if nothing else people are trying and thats good.
All will be solved when gravity rain becomes the popular view so we need not worry really.
The one thing I have learned on my wanderings trying to find out answers available re gravity is there is a lot of science out there that is no better than a form of religion. So many propositions are presented without what I am told to do each time I present my ideas. I wonder why high proofs are demanded to prove contrary yet if supporting the current popular view they are readily seen as supportive. I dont think I am the only enquirer who suffers from morosophia in fact my condition appears less extreme than many presenting views.
Thanks for your tollerance and understanding and the gems you reveal to me. You can go home but keep thinking about a solution.
alex
Under relativity nothing stops matter, energy and spacetime from being crushed into a singularity within the event horizon, but its pretty clear relativity doesn't apply within this framework - so why apply its dictates at all??
Just remember the name - relativity. Relativity describes the appearance of the black hole to us from the outside by virtue of the distortion of space and time around the enormous mass of the "black hole". It can't alone describe what is happening inside the event horizon. Maybe the best we'll ever do at describing the inside of the event horizon is speculation.
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Originally Posted by g__day
My brain is full, can I go home now sir?
Yeah... These sorts of discussions are extremely difficult in this type of forum IMO because the written word alone is very limiting, and we are all from such different backgrounds that's it's hard to establish the common ground to build on without confusion.
Or just for the sake of playing... the "inside" half (the core)...
He has an exceptional mind! But when you push the boundaries as he does, sometimes the boundary between science and philosphy gets crossed... it's just something we have to recognise and live with until we can move the boundary out around it - by either proving or disproving the idea. Basic scientific method.
, but I find some of the black hole radiation thing a bit hard to swallow
