Time is grinding into a halt?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Saint, Jun 25, 2012.

  1. rcscwc Registered Senior Member

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    BB needs to be in ICU.
     
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  3. prometheus viva voce! Registered Senior Member

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    This is worthless rubbish. The Schwarzschild solution is what allows us to calculate the many of the predictions which we have used to test general relativity.

    Take a read of the astronomy and cosmology posting guidelines - further trolling from you will result in punative action.

    Could you be any more vacuous?
     
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  5. Alan McDougall Alan McDougall Registered Senior Member

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    In a total void abscent of matter, energy and mass, a totally empty infinite void. I am not talking about space or spacetime here.

    If time is linked to matter, mass and the resultant gravity, surley in my "hypothetical void" time would be meaningless, or flow, for the lack of a better word, at infinite speed??

    Of course without anything to relate it to and outside observer would never notice this. Unless he could place something in this void and from his outsid viewpoint see it age and vanish in a relatively infinitely tiny moment!

    Another possibilty might be:


    So if you put a clock in this empty void and set it at say 12pm it would remain at 12pm forever
     
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  7. Boris2 Valued Senior Member

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    ok, you provide your theory and also provide the observational evidence to back it. with references please.
     
  8. KilljoyKlown Whatever Valued Senior Member

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    This article reports on the behemoth very early BH's. But I don't agree with their speculation as to how they happened to get so big so fast after the BB. Also, I really don't care what others might want to believe, and until more evidence is available, my speculation or theory could be as good as gold. In my opinion those BH's could not possibly get that massive in so short a period of time as a billion years. That only leaves one other possibility. They were in existence before the BB.

    http://www.nature.com/news/record-breaking-black-holes-fill-a-cosmic-gap-1.9553
     
  9. Alan McDougall Alan McDougall Registered Senior Member

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    The question would a total void consist of only three dimensions? (This would be only space, without time) or would it be four dimensions, this is the same as our universe of space-time, not what I am theorizing about!

    Why should I give you references this is my own theory, why the heck!! Can’t I provide a theory out of my own intellect, without trying to find someone else with similar ideas?

    Einstein’s Grand Theory of Relativity was only confirmed much later during an eclipse of the sun, when a star appeared in front of the sun instead of being behind it where it should have been at that particulat moment, due to gravitational distortion

    Only then could physicists give observational evidence for theorizing around this topic. Maybe I am an original thinker?
     
  10. KilljoyKlown Whatever Valued Senior Member

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    In the future it's a good idea to include the member ID you are directing your post to. I find clicking on the quote and then delete everything after the "]" that you don't want to comment about, works well, be sure and leave the /Quote in brackets at the end of the quoted stuff.

    For a few times use the Preview Post button until your comfortable with doing the deletes.
     
  11. brucep Valued Senior Member

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    The metric used to study rotating objects, such as neutron stars and black holes, is the Kerr Metric solution to Einstein's field equations. The maximum extremal rotating Kerr black hole rotates very close to the local coordinate speed of light. One that we're all familiar with, Cygnus X 1, has angular momentum per unit mass, J/m, of .75. It's considered an extremal Kerr black hole rotating at 3/4 local coordinate speed of light. I would hazard to guess most every collapsed star which winds up a black hole is extremal. Just a guess.
     
  12. Alan McDougall Alan McDougall Registered Senior Member

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    Imagine a single body in an otherwise infinite totally empty universe. In the absence of any forces, (Newton's second law gives):

    ma=0


    What does this equation imply?

    Following Newton we would conclude from that a=0 , that is, the body moves with uniform velocity. But there is now no longer a background against which to measure velocities or movement if you like

    Somehow I think velocity or movement must be linked to time and without one you could not fathom the other!

    Thus a=0 has no operational significance. Rather, the lack of any tangible background for measuring motion suggests that a should be "completely indeterminate" we might come to the remarkable conclusion that:

    If

    m=0
    Does the measure of inertia/movement depend on the existence of the background in such a way that in the absence of the background the measure vanishes?

    How could the concept of time exist in such a universe? Is time not linked to movement/velocity, and can you really comprehend the one without the other in my hypothetical empty universe?
     
  13. KilljoyKlown Whatever Valued Senior Member

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    I tried looking up extremal, but am still having a problem relating to how it applies to this subject?

    However I do have a question. When an object on the surface of a neutron star approaches the speed of light because of the rotation. The centripetal force must be measured in the hundreds of thousands of G's. At what point would the centripetal force exactly equal the force of gravity of the neutron star? If ever?
     
  14. Alan McDougall Alan McDougall Registered Senior Member

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    This is an excellent question that I must really go back and think deeply about, at the speed of light the CP should be infinite throwing the object outward from the BH, this is a paradox the object is not thrown out but drawn into the BH somehow?

    I would like to pose a siimlar question, if you have no objections!

    Let's assume that there is nothing in the universe except Earth. If the Earth rotates on its axis as it does, then would we experience the effects of rotational motion like centrifugal force and Coriolis force?

    The question is: is Earth rotating relative to space?
     
    Last edited: Jul 9, 2012
  15. KilljoyKlown Whatever Valued Senior Member

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    I believe it would be rotating mass minus the effects of external gravity from other sources. Yes we would experience the effects of rotational motion.
     
  16. kaduseus melencolia I Registered Senior Member

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    LOL?

    How about you show everyone where relativity describes the curvature inside the mass? Or show that the Schwarzschild is anything but two dimensional?
    The Schwarzschild solution is for all practical purposes an extension of the two dimensional gravitational rotation described by Newton in his second book, but applied to relativity, not classical mechanics. It shares the same flaw with Newtons description in that when the radius is within the mass and approaches zero, the curvature of spacetime, or angular velocity, approaches infinity.
    It's just easier to see, post Einstein, that the flaw in Newtons rotation occurs before zero radius, when the angular velocity approaches the velocity of light. That is the definition of a 'black hole', the mass from zero radius to the Schwarzschild radius, the mass is infinite for ANY volume or point within the Schwarzschild radius.

    If you expect the flaw to disappear just because your using relativity rather than classical mechanics then please show us why.
    Calling it a prediction instead of a flaw doesn't make it any more valid.
     
  17. prometheus viva voce! Registered Senior Member

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    Troll me one more time, please.

    What does this even mean? GR tells us that the presence of energy or matter deforms spacetime. By "curvature inside the mass," do you mean "what does GR say the gravitational field inside a star is?" If that's the case then there have been a number of studies using GR to compute the metric of a spheres. The only paper I can think of off the top of my head is by Bjorken et al who talk about the collapse of shells of matter and fluid spheres.

    I presume you are thinking of this type of picture:

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    The real Schwarzschild metric is \(ds^2 = -f(r) dt^2 + \frac{dr^2}{f(r)} + r^2 \left( d\theta^2 + sin^2(\theta) d\phi^2\right)\) with \(f(r) = 1- \frac{r_s}{r}\).

    Glance at that for the merest of seconds and you will see that there are 4 dimensions, \(t,r,\theta,\phi\). Specifically we have a system of polar coordinates which makes sense because the Schwarzschild solution is spherically symmetric. If you like you can easily generalise the Schwarzschild solution to any number of dimensions.

    In the light of what I wrote above, that the Schwarzschild metric is certainly not 2 dimensional, the stuff you wrote above is wrong. Additionally, when you consider gravity in 2 dimensions it becomes a lot simpler. Gravity in 2D is topological, meaning there are no propagating degrees of freedom. That's quite a subtle point, but it is interesting.

    The mass of a black hole is not infinite anywhere. I think you are getting confused with the density, which according to classical GR does diverge (but that tells us that GR is an incomplete theory - it is unable to deal with objects that are both very massive and very small which we would need a theory of quantum gravity to study). To get the mass of a black hole you simply have to integrate the 00 component of the energy momentum tensor, which you can work out from the Einstein equations. For the Schwarzschild metric you have the rather simple relation that \(r_s = 2M\), where I have set constants like c and G to 1.

    See above. Hopefully you can see now where some of your misunderstandings lie.
     
  18. brucep Valued Senior Member

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    Thanks for posting that Prometheus. Metric solutions, to the EFE, have made it possible for me to study GR with just a math level of calculus. They are the tools of GR. At least for me. I can't express how elegant and useful Einstein's gravitational model is.
     
    Last edited: Jul 10, 2012
  19. kaduseus melencolia I Registered Senior Member

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    Prometheus. First may I apologize for anything I have directed at you which you may feel is offensive or derisory, it was meant to be lighthearted and no offense intended.

    The picture you reference is a curvature of flat spacetime, spherically symmetric is essentially flat spacetime, I know you think it isn't, I consider it to be, it's like taking a flat spacetime and arbitrarily rotating it, reality doesn't work like that, if the sun worked like that then the planets would all have different orbital planes.

    So if Einstein considered black holes to be nonsense, and the Schwarzschild solution describes the curvature of spacetime (gravitational field) outside a mass, then who am I to argue with that?

    Mass in a black hole is not infinite? So to accelerate something to the velocity of light and beyond you need what? I not sure why I'm arguing that point really.

    To me the internal mechanics of masses like stars and galactic centers have a geometry that is reflected, yet isn't symmetric, about a plane, this geometry doesn't have an infinite curvature at the center, the center for all practical purposes has a curvature of 0.

    @KilljoyKlown re-quasars. I don't know really, I think they are a variety of different objects with the same pigeon hole name. But it's just an opinion.
     
  20. brucep Valued Senior Member

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    GR decides what geometry represents which spacetime. Not you. Your opinion is irrelevant. The problem with you is your disrespect for the scientific literature. The folks who write the literature know what it says. You don't.
     
  21. prometheus viva voce! Registered Senior Member

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    Fair enough.

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    Curvature is not something that's open to interpretation - it is computed from the metric. Schwarzschild spacetime is known as Ricci flat, which is another way of saying it is a solution to the Einstein equations in vacuum. With this condition the Ricci tensor (and therefore the Ricci scalar) is zero. The most basic measure of curvature is the Riemann tensor, and this is most certainly not zero. The Riemann tensor is zero if and only if the spacetime is globally flat.

    A point to note is that the Schwarzschild metric is the metric of a spherically symmetric empty space. As you pointed out, it is the metric of the exterior of a star or massive object, however one can show using Gauss' law for gravity that this is equivalent to a point mass at the centre of mass of the object in question, as long as some conditions I forget are obeyed (probably spherical symmetry and some other stuff). The point mass at r = 0 is excluded from the space as it is unphysical, leading us back to my previous comment about quantum gravity.


    It's been almost a century since Einstein came up with GR, so as you might expect what we know about it has dramatically increased. Believe it or not, grad students probably know more about GR than Einstein did - that's just the nature of scientific progress.

    Also, Einstein was not some physics god sent from above to always be infallible. Certainly Einstein was a great scientist who made one leap of genius, but people in the know will tell you that Einstein was wrong on a great number of things and there are many other people that were smarter than Einstein especially towards the end of his career (Einsteins contribution to physics after GR in the 1910's is almost zero, and he died in 1955). If you're interested look up the contributions to physics of people like Dirac, Feynman and Coleman to get you started.

    I presume you are talking about relativistic mass? This is one of the many reasons why relativistic mass is rubbish - mass is a constant, and if it were not relativity would be mathematically inconsistent.

    Speculate all you like, but just know that your speculation is basically a fairy story - there is no basis in reality for what you say at all, and until we understand the interior of a black hole better than we do now, it is essentially pointless to speculate at all.
     
  22. wellwisher Banned Banned

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    The way I understand relativistic mass is, it was added to space and time to prevent reference illusions. If we use just space and time, these allow one to create reference illusions. However, if you include relativistic mass you have to do an energy balance making the art of illusion harder. This is why it is downplayed; magician tricks are easier to perform without the energy balance.

    The relativistic mass is connected to the mass/energy equivalency associated with kinetic energy at relativistic velocity. Relativistic mass is not rest mass, but a mass/energy equivalent associated with the rest mass and implies an absolute reference due to the conservation of energy. If we leave relativistic mass out, there is no energy balance and we can do magic tricks with reference.

    As a simple example, say we are stationary and a train is moving. If we only are concerned with space and time, we can model either reference in motion since we only concerned with space and time. If we add the constraint of an energy balance the stationary references sees the kinetic energy of a train in motion, while the train sees the kinetic energy of the entire earth moving. These are not the same, with one energy balance not very likely. Therefore, we would conclude we are stationary and the train is moving. There is an absolute hierarchy of reference. Without the energy balance we can do a magic trick and have the earth moving with only a diesel engine. Many needed to downplay relativistic mass for various tricks to work.

    Relativistic mass reflects the shift in the kinetic energy curve as velocity approaches C, which is different from 1/2MV2. This shift assures you do the correct energy balance, if you decide to do one at all. Many don't even bother so they can know the hierarchy of the universal motion.

    For example, say we have two exact same rockets in relative motion. To one rocket I added X energy and to the other I added 3X energy. I suppose if we wanted to leave out relativistic mass and use only space-time we can say their motion is relative and either are in motion and the other stationary. But if we do the energy balance we know which is moving faster.

    In terms of the mind, space and time creates a 2-D view of the universe. Like with a piece of paper we draw 3-D images on a flat piece of paper. These look 3-D but lack depth since they only are 2-D. This is how the tricks works and is able to fool the mind. Below is an image of 3-D on 2-D.

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    There are also other tricks one can do with 3-D on 2-D. The best example is an artwork called relativity by Escher. It allows one to create an illusion in 2-D that cannot exist in 3-D. Relativistic mass requires a third variable so one is actually using 3-D. Below all references are the same, which cannot exist in the real world where there is gravitational energy potential. We leave out the energy balance of gravity then all appear the same.

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    Last edited: Jul 10, 2012
  23. AlexG Like nailing Jello to a tree Valued Senior Member

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    not at all
     

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