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Showing posts with label EOT-WASH GROUP. Show all posts
Showing posts with label EOT-WASH GROUP. Show all posts

Saturday, September 29, 2007

Production of Gravitational Waves

"My heart leaps up when I behold A rainbow in the sky."
William Wordsworth-- My Heart Leaps Up



This post is based on "the production" and not the detection of gravitational waves.

It does serve it's purpose, that I explain what I have in terms of detection, that one moves from that process, to actual production of them.:) Now I am not talking about Taylor and Hulse and PSR 1913+16 either.


Dr. Kip Thorne, Caltech 01-Relativity-The First 20th Century Revolution



Weber developed an experiment using a large suspended bar of aluminum, with a high resonant Q at a frequency of about 1 kH; the oscillation of the bar after it had been excited could be measured by a series of piezoelectric crystals mounted on it. The output of the system was put on a chart recorder like those used to record earthquakes. Weber studied the excursions of the pen to look for the occasional tone of a gravitational wave passing through the bar...



  • Einstein@Home



  • LIGO:



  • Nor am I talking about Kip Thorne, Webber, or Ligo operation for that matter.

    I am actually talking about the creation of gravitational waves.

    Now imagine that you see this "slide of light," and you were to think that in front of you, this would help you see where the gravitational field would be falling away from you. You would be sliding "ahead" from where you pointed and created this effect.

    So now you get the idea here of what I propose in the production of gravitational waves versus the detection of them?:)


    Up until this point in time, I've used the term "generate" to describe the capability of producing a gravitational field, but since I'm not aware of any way of creating a gravitational field from nothing, a more accurate term might be to "access and amplify" a gravitational field. And this is what I mean when I use the term "generate". To understand how gravity is generated or "accessed and amplified", you must first know what gravity is.


    While watching a television program I listened to what he had to say. For people interested in gravity, Quantum or otherwise, this topic helped captured my change in thinking that is postulated, and one I am giving thought right now.

    The Problem


    Gravitational waves are produced when there is a change in the curvature of spacetime. Since the shape of spacetime depends only on how mass is distributed, events that change the distribution of mass cause gravitational waves. It takes events with a lot of energy to make gravitational waves that we can detect because spacetime is not very elastic. Remember the bowling ball analogy? Space-time is like a stiff trampoline, one that only sinks when you put something very heavy on it.


    So if we are to consider such a thing how would I go about it? Perhaps, "jumping up and down?":)


    “Every time you accelerate—say by jumping up and down—you’re generating gravitational waves,” says Rainer Weiss, Professor Emeritus of Physics at MIT. “There’s no doubt of it.” But just standing there won’t cut the mustard. To make a wave, your mass has to both move (have velocity) and have acceleration (change the rate of motion, direction, or both).

    Still, don’t get your hopes up. No matter how fast you jump, sprint, or cartwheel, the resulting warp your waves make on space is so weak that it’s utterly unmeasurable—perhaps 100,000,000,000,000,000,000,000 times less so than the warp made by massive exploding space objects. And LIGO has a tough enough time measuring those.


    So there are questions on my mind, about gravity creation.

    Plato writes:


    Dorigo,

    I am interested as a lay person in the collider experiments and wondered about "gravitational wave production."

    Considering quark gluon levels reached I wondered about the strength and the weakness as a measure of gravitational waves within that collider action. If microscopic blackhole are created then would it be wrong to observe, variation of gravity within the domain of the collider itself?

    regards,


    See following comment posted here.

    Dear Plato,

    quarks are microscopic bodies. The gravitational effects associated with the motion and interaction of masses that small are ridiculously small.

    In theories contemplating a low quantum gravity scale, black holes could in principle be created in high energy collisions, but if a chance of detecting their creation exists, it is not by gravitational effects, which remain billions of billions of billions of billions (and then some) of times smaller than those caused by strong interactions.

    Please check my post on Lisa Randall’s seminar (Sept. 29th), or the one on the seminar given by Steve Giddings last March. There is reading material that I tried to make accessible to most there.

    Cheers,
    T.


    I will be loking at this in much more detail. Something that immediately came to mind is Gran Sasso. "Muon creation" from the particle collisions. See: Neutrino Mixing in Sixty Seconds.

    This summer, CERN gave the starting signal for the long-distance neutrino race to Italy. The CNGS facility (CERN Neutrinos to Gran Sasso), embedded in the laboratory's accelerator complex, produced its first neutrino beam. For the first time, billions of neutrinos were sent through the Earth's crust to the Gran Sasso laboratory, 732 kilometres away in Italy, a journey at almost the speed of light which they completed in less than 2.5 milliseconds. The OPERA experiment at the Gran Sasso laboratory was then commissioned, recording the first neutrino tracks. See Strangelets and Strange Matter


    The Distorted Lense

    It would seem to me that if any lens could direct "the focus of our vision" then why not the focus of the gravitational waves? I mean if there is a "inverse calculation" to waves, it would seem t me that such a process could point to a heavy concentration in terms of blackhole production?


    As one of the fields which obey the general inverse square law, the gravity field can be put in the form shown above, showing that the acceleration of gravity, g, is an expression of the intensity of the gravity field.


    As I am reading different thoughts are manifesting and one of these has to do with the "escape velocity of the photon." Why I am not sure at the moment. This used as a measure of determination of whether a blackhole exists? How did we arrive at such a point?


    Albert Einstein (1879–1955)


    One part of the theory of Relativity was inspired when a painter fell off a roof. Einstein found out that while the painter was falling freely, he felt weightless. This led Einstein to realize that gravity was a form of inertia, a result of the way things moved through space - and General Relativity was born.


    It is important for me to recognize the collider process in context of what it is experimentally doing. For me this is demonstrating a "geometrical process" even if it is being taken down to the such "weak gravitational ranges" that I would point to what would manifest,if a tunnelling effect occurred from one location to the next.

    Time travel

    Plato:Thus the initial idea here to follow is that the process had to have a physics relation. This is based on the understanding of anti-particle/particle, and what becomes evident in the cosmos as a closed loop process. Any variation within this context, is the idea of "blackhole anti-particle expression" based on what can be seen at the horizon?Tunneling in Faster then Light


    Warp Drives", "Hyperspace Drives", or any other term for Faster-than-light travel is at the level of speculation, with some facets edging into the realm of science. We are at the point where we know what we do know and know what we don’t, but do not know for sure if faster than light travel is possible.

    The bad news is that the bulk of scientific knowledge that we have accumulated to date concludes that faster than light travel is impossible. This is an artifact of Einstein’s Special Theory of Relativity. Yes, there are some other perspectives; tachyons, wormholes, inflationary universe, spacetime warping, quantum paradoxes...ideas that are in credible scientific literature, but it is still too soon to know if such ideas are viable.

    One of the issues that is evoked by any faster-than-light transport is time paradoxes: causality violations and implications of time travel. As if the faster than light issue wasn’t tough enough, it is possible to construct elaborate scenarios where faster-than-light travel results in time travel. Time travel is considered far more impossible than light travel.


    It would be suspect to me that such travelling in space would allow for the manufacture of gravitational influences to be pointed in the "direction of travel" and allow such slippage away from that current position.

    Gravitational Mass for a Photon

    The relativistic energy expression attributes a mass to any energetic particle, and for the photon



    The gravitational potential energy is then



    When the photon escapes the gravity field, it will have a different frequency




    Since it is reduced in frequency, this is called the gravitational red shift or the Einstein red shift.

    Escape Energy for Photon

    If the gravitational potential energy of the photon is exactly equal to the photon energy then



    Note that this condition is independent of the frequency, and for a given mass M establishes a critical radius. Actually, Schwarzchilds's calculated gravitational radius differs from this result by a factor of 2 and is coincidently equal to the non-relativistic escape velocity expression




    A black hole is an object so massive that even light cannot escape from it. This requires the idea of a gravitational mass for a photon, which then allows the calculation of an escape energy for an object of that mass. When the escape energy is equal to the photon energy, the implication is that the object is a "black hole."


    For more see "Time as a measure.

    By allowing new physics to emerge, what basis is being held relevant then to what is being created in the particle collisions that are indeed faster then light?


    As we know from Einstein’s theory of special relativity, nothing can travel faster than c, the velocity of light in a vacuum. The speed of the light that we see generally travels with a slower velocity c/n where n is the refractive index of the medium through which we view the light (in air at sea level, n is approximately 1.00029 whereas in water n is 1.33). Highly energetic, charged particles (which are only constrained to travel slower than c) tend to radiate photons when they pass through a medium and, consequently, can suddenly find themselves in the embarrassing position of actually travelling faster than the light they produce!

    The result of this can be illustrated by considering a moving particle which emits pulses of light that expand like ripples on a pond, as shown in the Figure (right). By the time the particle is at the position indicated by the purple spot, the spherical shell of light emitted when the particle was in the blue position will have expanded to the radius indicated by the open blue circle. Likewise, the light emitted when the particle was in the green position will have expanded to the radius indicated by the open green circle, and so on. Notice that these ripples overlap with each other to form an enhanced cone of light indicated by the dotted lines. This is analogous to the idea that leads to a sonic boom when planes such as Concorde travel faster than the speed of sound in air


    See also information on What is Cerenkov Radiation?

    Fifth Dimensional General Relativity

    It was a gradual process that using Grace to help me see the earth in new ways was paramount to the inclusion principle of electromagnetism contained within the move to GR.I may be mixed up here, and I have no one to say.

    "Color of gravity" assumes that you have seen the colour of gravity in relation to this slide of light. So seeing in such a way would seem relevant in the fifth dimensional perspective.

    In Kaku's preface of Hyperspace, page ix, we find a innocent enough statement that helps us orientate a view that previous to all understanding, is couched in the work of Kaluza.

    In para 3, he writes,

    Similarily, the laws of gravity and light seem totally dissimilar. They obey different physical assumptions and different mathematics. Attempts to splice these two forces have always failed. However, if we add one more dimension, a fifth dimension, to the previous four dimensions of space and time, then equations governing light and gravity appear to merge together like two pieces of a jigsaw puzzle. Light, in fact, can be explained in the fifth dimension. In this way, we see the laws of light and gravity become simpler in five dimensions.


    I would think such a thought here by Kaku would have stimulated the brains of people to see that a direct result is needed in our reality to which such thoughts I am giving would allow you to see gravity in new ways?



    Lagrangian views with regards to relations between the Earth, Moon and Sun would help one to see the general outlay of gravitational influences in space. That is also part of the work I have been following to understand the spacetime fabric and how we may see this in our dealings.

    Wednesday, March 07, 2007

    Gravity Experiments

    No matter how absurd? :)

    From a early age, young Albert showed great interest in the world around him. When he was five years old, his father gave him a compass, and the child was enchanted by the device and intrigued by the fact the needle followed a invisible field to point always in the direction of the north pole.Reminiscing in old age, Einstein mentioned this incident as one of the factors that perhaps motivated him years later to study the gravitational field. God's Equation, by Amir D. Aczel, Pg 14

    So you fast forward a few years and what have you got with regards to nature accompany the man who fell off his roof?


    Albert Einstein (1879–1955)

    One part of the theory of Relativity was inspired when a painter fell off a roof. Einstein found out that while the painter was falling freely, he felt weightless. This led Einstein to realize that gravity was a form of inertia, a result of the way things moved through space - and General Relativity was born.


    So it is "by accident" General Relativity was born? Having things happen within context of natures own timing leaves one with some impressions it seems? How often have you noticed the outside world while you are doing your abstract thinking? What is so conducive that the open doorway allowed this other information to flow quite freely into the mind's cavity? You happebn to be working woth natures and it's puzzles yet what use any of these geometrical forms?

    Plato:
    It is of course with some concern that any scientific mind, held to the established rules of his organizational, "motto of acceptance of the stringent rules of science" would allow such room, as to imbue the human being with qualities greater then, the value assigned to subjective valuations.


    So having faced the idea of the "gravitonic condensation" what use this idea(a painting) in terms of what we see as we spell out the differences between micro lensing and "gravitational lensing" how light travels from those distant points in the universe?

    This miniature drop tower is used by Microgravity man and others to demonstrate the effects of reduced gravity on physical and chemical phenomena that are normally masked by Earth's gravity.

    I know about people distancing themselves from what may indeed trouble them, as if, one presented some "anomaly in nature" that I/you may have never seen before. Do I take them on face value for what we had know of them? While reading their blog over the years, months, days, what conclusion had you reached?? Superman, Spiderman, and Captain Marvel comics which glorify the hero? Spheres, as bubbles in gravity free environment are always a nice thing to consider.

    A bubble is a minimal-energy surface of the type that is formed by soap film.

    I selected Kuhn because I was speaking directly to what was evident in my own life. What was presented to me "as the experience" may have likewise captivated a young child of 5, while another is trouble by symmetry in a "qualitative style."

    I began my own investigations, and this set the course for my life to understand what had happened. How ever absurd one may find my statement in the previous post, it is a fact that I do not know how it was accomplished, but I did indeed see the effect of the person free of what we know as gravity holding the individual to her bosom.

    So you have this statement. Q9 said,"the outer gravity which keeps our feet firmly on the ground."



    So how was I suppose to react given the circumstances I had mentioned? If I said the mind was involved in the process "what proof do I have" that the person could indeed do the things that defy, what a frog may do for one who likes to wear shoes that make them light on their feet?

    So any concept which had spoken about gravity, to one extent or another, has entered my research, for me to find some way that would allow such a thing to entertain the sceptic, as well as take the form of flowery pot comments. "Concepts" as foolish as the bulk?

    Of course I want to know what happen in the way that young Einstein wondered about the mystery of nature assigned to that needle. We know now don't we? Oh, gravity is weak here on earth? Weaker then the magnet that is attached itself to the fridge.

    So when gravity had ever been strong? How strong, that it could reach only so far?

    Friday, January 19, 2007

    No Extra Dimensions Yet?

    Turning back to gravity, the extra-dimensions model stems from theoretical research into (mem)brane theories, the multidimensional successors to string theories (April 1999 p13). One remarkable property of these models is that they show that it is quite natural and consistent for electromagnetism, the weak force and the inter-quark force to be confined to a brane while gravity acts in a larger number of spatial dimensions.
    The requirement of correctly reproducing Newton's constant, G, at long distances leads to the size of the extra dimensions in which gravity is free to act being related to the number of extra dimensions.



    New physics experience might reveal more dimensions in the Universe than meets the eyeSee Here

    Amazing isn't it that EOT-WASH GROUP would consider themselves as challenging the experimental basis of string theory thinking. If one did not see into the nature of that "dynamical world" what value would have ever been reached if there was no separation in the value of the "r distance?" No "varying energy valuation" in the strong force.


    Fig. 1. In quantum chromodynamics, a confining flux tube forms between distant static charges. This leads to quark confinement - the potential energy between (in this case) a quark and an antiquark increases linearly with the distance between them.See Here.

    If a "Q to Q" measure is considered and a "active consideration evident" in this exchange of a "r value," then why would they think the gravitational considerations would not have ever made sense in the distances of extra dimensions of 44 micrometres or larger?

    By increasing this distance, the gravitational considerations are very important in terms of the energy valuation given as the "q to q" is moved apart. The energy is directly relate to the gravitational considerations?


    Image: EOT-WASH GROUP, UNIVERSITY OF WASHINGTON

    Discovering extra dimensions with the relatively huge size of a few micrometers would offer spectacular confirmation for string theory, the still unproved body of equations that may unify gravity with the normally incompatible realm of quantum physics. "Even though we haven't seen anything, these results put boundaries on what people can legitimately propose," says experimental physicist and study author Eric Adelberger of the University of Washington. "Testing the inverse square law [meaning Newton's law of gravity] is the bombproof way to look for extra dimensions.
    "


    some physicists proposed that string theory might cause gravity to grow stronger at such distances if the universe came with relatively big extra dimensions of micrometers in width......Sundrum says that if extra dimensions failed to turn up at that distance, it would likely prune off that branch of string theory.

    Tuesday, January 16, 2007

    Newton's inverse-square (1/r2) law

    The standard model of particle physics is a self-contained picture of fundamental particles and their interactions. Physicists, on a journey from solid matter to quarks and gluons, via atoms and nuclear matter, may have reached the foundation level of fields and particles. But have we reached bedrock, or is there something deeper? Savas Dimopoulos


    While in the post previous to this I gave some indication of the gravity from the cosmological point of view, I then took it down to the particle collisions. I again reiterate this, in this post as well.


    Source-detector configuration for the 1-m 1/r2 test
    Newton's inverse-square (1/r2) law is a cornerstone of General Relativity. However, this law has been challenged by many modern theories of gravity and particle physics. The supergravity and unified field theories often run into a new short-range force, with an accompanying new particle, which should appear as a violation of the 1/r2 law. More recently, a possible violation of the 1/r2 law in the range below 1 mm was suggested by string theories with extra dimensions.



    Gravity: Another Example of a 1/R2 Law
    Two masses at a given distance place equal and opposite forces of attraction on one another. The magnitude of this force of attraction is given by:




    where G is the universal gravitation constant (6.67 X 10-11 Nm2/kg2), m1 is the mass of the first object in kilograms, m2 is the mass of the second object in kilograms, and r is the distance between the centers of the two masses, in meters.


    It is not without thinking here that what you thought of the "microstate blackhole," could have found it's relevance in the temperatures reached, when seen at this level?


    Fig. 1. In quantum chromodynamics, a confining flux tube forms between distant static charges. This leads to quark confinement - the potential energy between (in this case) a quark and an antiquark increases linearly with the distance between them.
    The ideal experimental test of this new feature of QCD would be to study the flux tube of figure 1 directly by anchoring a quark and antiquark several femtometres apart and examining the flux tube between them. In such ideal circumstances, one of the characteristics of the gluonic flux tube would be the model-independent spectrum shown in figure 2. The excitation energy is p/r because the flux tube's mass is entirely due to its stored energy. There are two initially excited longest wavelength vibrations with identical energies because the motion of the flux tube is in the two symmetrical dimensions perpendicular to its length.


    You ever hear of the term, "you can't hit the broad side of a barn?" WEll lets think about this when it comes to the measures of femtometres and such. Classically old, it was not witout some direction in thinking that one could be taken down to certain measures for those same considerations. Barn Yard?

    Origin of the (classified) barn

    In the luminosity lexicon, a picobarn is one trillionth (10-12) of a barn, and a femtobarn is one quadrillionth (10-15) of a barn... but what's a barn? The distinctive and amusing term originated with two Purdue University physicists working on the Manhattan Project in 1942—and it was classified information by the US government until after World War II.

    A History of Physics at Purdue (Gartenhaus, Tubis, Cassidy, and Bray) cites the July 1972 issue of Physics Today in which Marshall Halloway and Charles Baker write of tossing around ideas over dinner until arriving at "barn" to describe the typical nuclear cross section of 10-24 cm2, the effective target area that a nuclear particle represents in a collision. Dining in the Purdue Memorial Union, back in Lafayette, Indiana, Halloway and Baker dismissed "Oppenheimer" and "Bethe" as candidates, then considered John Manley, director of the Purdue group at Los Alamos. They decided "Manley" was too long, and then, as the authors put it in the Physics Today article to:


    So here we are looking at what the EOT-WASH GROUP is doing? What is "compactification" in line with any thinking, that the world around us from a cosmological point of view is large(large circle), and that amidst it's reality, exists this finer world of particulars that "we'd only imagine" while the measures to it's finest(small circle) was produce and then energies assigned.

    It would be as if you looked at the cosmos and never thought about it constituents "bits and pieces," which make up those cosmological processes. Yet, for me, "circles within circles" would have made me wonder which circle represented which part of the views at any one time, whilst we speak about these energies from one perspective to the next.

    Savas Dimopoulos:At close encounter the particles can exchange gravitons via the two extra dimensions, which changes the force law at very short distances. Instead of the "Newtonian inverse square law" you’ll have an inverse fourth power law. This signature is being looked for in the ongoing experiments.


    .....and more here for how perspectve can change once you give a direction in which to think about.

    Savas Dimopoulos:At first we faced denial. We had deliberately used the word "sub-millimeter" in our first paper. Physicists were surprised, to say the least, that such a thing was not already excluded experimentally. I remember a stage in 1998 when colleagues wondered if we had not forgotten some crucial experiment. We were not discouraged. No! We gave talks on the ideas, and by July 1998 had analyzed the laboratory and cosmological constraints. That paper marked a sea-change in opinion: physicists began to think this was an interesting idea. By the fall of 1998 we were showing how to do real physics. Now several study groups are taking us very seriously: the high citation rates speak for themselves.
    Personally I am not surprised by the reaction. Revolutionary ideas go through a cycle: denial, followed by "okay it is consistent but can you do anything with it?" and finally, once you show how to do real physics, you may get the third phase where many physicists become interested in the field. The same thing happened to me and Giorgi back in 1981 when we first proposed the supersymmetric extension of the standard model of particle physics. Initially there were the usual skeptics but now it is completely accepted.
    Oddly, for me, the major competitor to these proposals for extra dimensions is the supersymmetry extension. But let's recall some of the disadvantages of the standard model. First, it shuts out gravity. Second, it has 18 free parameters, many of them very small. Third, the vacuum energy is 120 orders of magnitude larger than what you would naively guess from the standard model.
    Proposing extra dimensions to space is a drastic step. But once you have the extra space you can attribute the smallness of some quantities to the statement that their origin is somewhere far away inside space, just as an astronomer might attribute the faintness of a galaxy to its large distance. For example, maybe the smallness of the electron mass arises because its origin is far away inside the extra dimensions.
    My view is that both of the big ideas I have worked on are testable in the next decade by LHC. The two frameworks have complementary features. I'm greatly looking forward to the outcome


    Make sure you look at the "compactification" label to the right index

    Saturday, December 03, 2005

    General Relativity

    I took GR because I thought Neil Turok was dreeeamy.


    Well I dunno? He certainly got me thinking about brane world collisions, along with steinhardt, that’s for sure. We are most certainly dealing with a cosmological placement here with General relativity, but has been extended, as we look at string/M theoretical successes.



    You had to make "certain assumptions I know" in order to get here in the picture, and you had to have some inkling of what gravitational waves were and how they were transmitted.

    Completed 720 degree rotations, as "tidbits" of the process which are given to us from a cosmological standpoint.


    So what is transmitted in the bulk in terms of "gravitational lensing" has some relation, to what we see in the picture above. Look at the placement of the gravitons in bulk perspective and how they are concentrated on and around the brane.

    So it is not without reason that we see bulk perspective as a extension and not scientifically up to the challenege because Peter Woit say so?

    Modifications to General Relativity

    So "six weeks" we should have known something by now with respect to below statements? Jo-Anne, of cosmic varaince selected this answer next to the Pioneer Anomalie.

    Eric Adelberger on Aug 12th, 2005 at 2:37 pm
    Please don’t get too excited yet about rumors concerning the Eot-Wash test of the 1/r^2 law. We can exclude gravitational strength (|alpha|=1) Yukawa violations of the 1/r^2 law for lambda>80 microns at 95% confidence. It is true that we are seeing an anomaly at shorter length scales but we have to show first that the anomaly is not some experimental artifact. Then, if it holds up, we have to check if the anomaly is due to new fundamental physics or to some subtle electromagnetic effect that penetrates our conducting shield. We are now checking for experimental artifacts by making a small change to our apparatus that causes a big change in the Newtonian signal but should have essentially no effect on a short-range anomaly. Then we will replace our molybdenum detector ring with an aluminum one. This will reduce any signal from interactions coupled to mass, but will have little effect on subtle electromagnetic backgrounds. These experiments are tricky and measure very small forces. It takes time to get them right. We will not be able to say anything definite about the anomaly for several months at least.


    As stated maybe this "anomalie" might be significant and for scientists it is necessary such a quirk of nature be seen and understood. I relayed Einstein's early youth and the compass for a more introspective feature that such anomalies present.

    The Eotwash Group is a sign of relief, for the speculative signs attributed from other scientists, made this topic of extra-dimensions unbearable and unfit for the general outlay for scientists who did not understand this themselves.

    Deviations from Newton's law seen?

    So what does Lubos have to say about this in his column?

    Lubos Motl:
    The most careful and respected experimental group in its field which resides at University of Washington - Eric Adelberger et al. - seems to have detected deviations from Newton's gravitational law at distances slightly below 100 microns at the "4 sigma" confidence level. Because they are so careful and the implied assertion would be revolutionary (or, alternatively, looking spectacularly dumb), they intend to increase the effect to "8 sigma" or so and construct different and complementary experiments to test the same effect which could take a year or two (or more...) before the paper is published. You know, there are many things such as the van der Waals forces and other, possibly unexpected, condensed-matter related effects that become important at the multi-micron scales and should be separated from the rest.


    On Relativity again


    According to General Relativity, the key qualities of strong sources of gravitational waves are that they be non-spherical, dynamic (i.e. change their behavior with time), and possess large amounts of mass moving at high velocities. So prime suspects should exhibit one or more of the following characteristics.


  • 1. Spinning

  • 2. Mass tranfer

  • 3. Collpase

  • 4. Explosion

  • 5. Collision


  • As to “online resources” for General Relativity, is there one preference if you do not have access to the Hartle book or the other?

    Lecture Notes on General Relativity, by Sean Carroll

    Preface
    These lectures represent an introductory graduate course in general relativity, both its foundations and applications. They are a lightly edited version of notes I handed out while teaching Physics 8.962, the graduate course in GR at MIT, during the Spring of 1996. Although they are appropriately called \lecture notes”, the level of detail is fairly high, either including all necessary steps or leaving gaps that can readily be filled in by the reader. Nevertheless, there are various ways in which these notes differ from a textbook; most importantly, they are not organized into short sections that can be approached in various orders, but are meant to be gone through from start to finish. A special effort has been made to maintain a conversational tone, in an attempt to go slightly beyond the bare results themselves and into the context in which they belong


    Or a link to this one for a historical look?

    Relativity
    The Special and General Theory

    Friday, August 12, 2005

    What! Superficiality has extra dimensions to it?

    Sometimes I like to play, "knock knock whose there" on my head. :)

    Quantitative studies of future experiments to be carried out by LHC show that any signatures of missing energy can be used to probe the nature of gravity at small distances. The predicted effects could be accessible to the Tevatron Collider at Fermilab, but the higher energy LHC has the better chance.

    These colliders are still under construction, but results also have consequences for "table-top" experiments, being carried out here at Stanford, as well as the University of Washington and the University of Colorado. Here’s the basic idea: imagine there are two extra dimensions on a scale of a millimeter. Next, take two massive particles separated by a meter, at which distance they obviously behave according to the well-known rules of 3-D space. But if you bring them very close, say closer than one millimeter, they become sensitive to the amount of extra space around. At close encounter the particles can exchange gravitons via the two extra dimensions, which changes the force law at very short distances. Instead of the Newtonian inverse square law you’ll have an inverse fourth power law. This signature is being looked for in the ongoing experiments.


    Eöt-Wash Group


    However, until evidence for new physics is found, it is clearly better to work on tests of the inverse-square law than on equivalence-principle tests: the 1/r2 tests are more general (probing all finite-range effects), and more sensitive (in particle-exchange scenarios the composition-dependence is expected to be a relatively small fractional effect). But testing the gravitational 1/r2 law for length scales less than 50 µm will probably require a somewhat different technology. In a planar geometry (optimum because one gets the maximum amount of mass in close proximity) the signal of a short-range Yukawa interaction drops as roughly the 4th power of the Yukawa range while extraneous disturbances stay roughly the same size. This will present an interesting challenge for future experimental work.


    Imagine, if such assertions to extra-dimension were just superficial statements drawn from historical literature that people drummed up to create mysticism? Oh how safe I would feel drawing from such statements, that wonder of all wonders, there was a scientific basis assigned this perspective of Georgi's.


    Georgi Dvali


    Dvali posits that this leakage has a profound effect on the gravitational force between objects separated by more than the critical distance. Specifically, the theory of modified gravity has a characteristic length-scale r_c, or approximately 15 billion light years. This marks a crossover distance beyond which the cosmological expansion becomes accelerated, and thus, from cosmological observations r_c is fixed to be the size of the observable universe. Even though r_c scale is enormous, the imprints of modification are detectable at much shorter distances because of the additional gravitational force.

    "This is the crucial difference between the dark energy and modified gravity hypothesis, since, by the former, no observable deviation is predicted at short distances," Dvali says. "Virtual gravitons exploit every possible route between the objects, and the leakage opens up a huge number of multidimensional detours, which bring about a change in the law of gravity."

    Dvali adds that the impact of modified gravity is able to be tested by experiments other than the large distance cosmological observations. One example is the Lunar Laser Ranging experiment that monitors the lunar orbit with an extraordinary precision by shooting the lasers to the moon and detecting the reflected beam. The beam is reflected by retro-reflecting mirrors originally placed on the lunar surface by the astronauts of the Apollo 11 mission.


    I think Eddington expeirment and methods used in LIGO speak directly to the range of sublte thinking that was necesary from a broad landscape of bulk gravitonic perception, that could be the effect of such things as lensing, dilation and gravtonic scattering effects?

    So we understand here do we, that procedures to conceptual fabrication has some basic formulation to those short distances? Eöt-Wash Group was also asking something about these short distances were they not? The history her eis a short one from 2001 but it bascialy answer soem questions about what those extra dimensions mean.

    So don't take my word for it or someone who just scoffs at the very notion. Apply yourself to see what is meant. Maybe you will tend to wonder what crazy ideas Brian Josephson had about the nature of civilzations living amidst our own?

    Rumour of New Forces
    Just had a look at Cosmic Variance and found this statement by Sean Carroll about the Eotwash group update. Here is what Eric Adelberger had to say.

    Eric Adelberger on Aug 12th, 2005 at 2:37 pm
    Please don’t get too excited yet about rumors concerning the Eot-Wash test of the 1/r^2 law. We can exclude gravitational strength (|alpha|=1) Yukawa violations of the 1/r^2 law for lambda>80 microns at 95% confidence. It is true that we are seeing an anomaly at shorter length scales but we have to show first that the anomaly is not some experimental artifact. Then, if it holds up, we have to check if the anomaly is due to new fundamental physics or to some subtle electromagnetic effect that penetrates our conducting shield. We are now checking for experimental artifacts by making a small change to our apparatus that causes a big change in the Newtonian signal but should have essentially no effect on a short-range anomaly. Then we will replace our molybdenum detector ring with an aluminum one. This will reduce any signal from interactions coupled to mass, but will have little effect on subtle electromagnetic backgrounds. These experiments are tricky and measure very small forces. It takes time to get them right. We will not be able to say anything definite about the anomaly for several months at least.


    As stated maybe this anomalie might be significant and for scientists it is necessary such a quirk of nature be seen and understood. I relayed Einstein's early youth and the compass for a more introspective feature that such anomalies present.

    The Eotwash Group is a sign of relief, for the speculative signs attributed from other scientists, made this topic of extr-dimensions unbearable and unfit for the general outlaid of scientists who did not understand this themselves.

    Deviations from Newton's law seen?

    So what does Lubos have to say about this in his column?

    Lubos Motl:
    The most careful and respected experimental group in its field which resides at University of Washington - Eric Adelberger et al. - seems to have detected deviations from Newton's gravitational law at distances slightly below 100 microns at the "4 sigma" confidence level. Because they are so careful and the implied assertion would be revolutionary (or, alternatively, looking spectacularly dumb), they intend to increase the effect to "8 sigma" or so and construct different and complementary experiments to test the same effect which could take a year or two (or more...) before the paper is published. You know, there are many things such as the van der Waals forces and other, possibly unexpected, condensed-matter related effects that become important at the multi-micron scales and should be separated from the rest.


    See:

  • Inverse Fourth Power Law